This is only a preview of the August 2012 issue of Silicon Chip. You can view 30 of the 104 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Articles in this series:
Articles in this series:
Articles in this series:
Items relevant to "The Driveway Sentry Mk.2":
Items relevant to "Timer For Fans And Lights":
Items relevant to "Isolated High-Current Adaptor For Scopes & DMMs":
Items relevant to "Wideband Oxygen Sensor Controller Mk.2, Pt.3":
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AUGUST 2012
ISSN 1030-2662
08
9 771030 266001
Special feature:
PRINT POST APPROVED
- PP255003/01272
9
$ 30* NZ $ 11 90
INC GST
INC GST
ELECTRIC ’COPTERS!
’COPTERS!
How do they fly?
We review the
Parrot Quadcopter
Flying for business
as well as fun!
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we take our report!
e’s
and her
TO BUILD:
siliconchip.com.au
Driveway Sentry – added property security
Automatic Fan Timer – for those who forget!
August 2012 1
Current Adaptor - make measurements safely
Completing the Wideband Oxygen Sensor
ATTENTION KIT BUILDERS
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If you can’t find the kit you are looking for, try the Jaycar Kit
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Just search for “kit back catalogue”.
PACKAGE DEAL!
Hand-Held pH Meter
ESD Safe Solder/Desolder
Station (TS-1574 $369.00)
Solder Fume Extractor
A simple, portable and accurate device
for checking pH levels in water. Readings
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• Resolution: 1-14 pH
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• Accuracy:+/- 0.2 pH
• Size: 40(W) x
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59
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Features a large, easily read display
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Compact Switchmode Laboratory
Power Supplies
10 Way Blade Fuse Block with
LED Indicators
Features a common supply rail
and includes a removable
protective cover and LED
indicators for each fuse.
Perfect for automotive or
marine applications.
• Size: 95(L) x 85(W) x 36(H)mm
SZ-2008
Compact size, high current, variable output and fan cooling
make these the ideal power supply for your bench. They are
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display a warning LED in the event of a fault condition.
Current and voltage are displayed on separate backlit
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• Size: 148(W) x
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• 20 x 5A, 10A, 15A,
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• 1200mm floor mode height
• 600mm desk mode height
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23
Consumes only 9W of power whilst
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• PCB: 49.5 x 34mm
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Price valid until 23/08/2012
3995
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PCB Drill Chuck
This chuck will allow you to use
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TD-2010 Was $9.95
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www.jaycar.com.au
Contents
SILICON
CHIP
www.siliconchip.com.au
Vol.25, No.8; August 2012
Features
12 We Drive Nissan’s Leaf Electric Car
Were we just a little impressed? No way; we were VERY impressed with the
Nissan Leaf electric car and the technology it uses – by Ross Tester
18 Multi-Rotor Helicopters
A revolution is taking place with Remotely Piloted Aircraft (RPAs), with quadcopters and other multi-rotor helicopters leading the way – by Bob Young
24 Flying The Parrot AR Drone 2 Quadcopter
Impressive flying machine sports four rotors plus two cameras and can be
controlled using an iPhone, iPad or Android device – by Nicholas Vinen
We Drive Nissan’s Leaf Electric
Car – Page 12.
12.
28 RPAs: Designing, Building & Using Them For Business
SILICON CHIP talks to two enthusiasts turned businessmen who are now using
RPAs for movie and TV cinematography – by Ross Tester
Pro jects To Build
36 The Driveway Sentry Mk.2
It detects vehicles moving along a driveway and activates a relay to switch on
lights and activate a piezo buzzer for a preset period – by Jim Rowe
64 Timer For Fans And Lights
Use it to make a bathroom fan run for a set period after the switch has been
turned off or to turn on a light for a set period of time – by Nicholas Vinen
Detect Moving Vehicles With The
Driveway Sentry Mk.2 – Page 36.
70 Isolated High-Current Adaptor For Scopes & DMMs
It lets you safely monitor and measure mains currents using your DMM or
scope. It also works with DC and has much better resolution and bandwidth
than most clamp meters – by Nicholas Vinen
82 Wideband Oxygen Sensor Controller Mk.2, Pt.3
Final article describes how the oxygen sensor is installed in a car and
connected to the Wideband Controller – by John Clarke
Special Columns
31 Circuit Notebook
(1) PICAXE-Based Non-Lethal Mouse Trap; (2) 7-Day Programmable Alarm
Clock with 230VAC Switching; (3) Serial Cable For Old Computers; (4) Using
Two PC Power Supplies For 24V; (5) Voltage Regulator For A Mitsubishi Van
Timer For Fans & Lights
– Page 64.
58 Serviceman’s Log
Watchmaking is not really my forte
88 Vintage Radio
The Dutch Philips BX373A 4-valve receiver – by Rodney Champness
Departments
2
4
57
95
Publisher’s Letter
Mailbag
Product Showcase
Order Form
siliconchip.com.au
96 Ask Silicon Chip
103 Market Centre
104 Notes & Errata
Isolated High-Current Adaptor For
Scopes & DMMs – Page 70.
August 2012 1
SILICON
SILIC
CHIP
www.siliconchip.com.au
Publisher & Editor-in-Chief
Leo Simpson, B.Bus., FAICD
Production Manager
Greg Swain, B.Sc. (Hons.)
Technical Editor
John Clarke, B.E.(Elec.)
Technical Staff
Ross Tester
Jim Rowe, B.A., B.Sc
Nicholas Vinen
Photography
Ross Tester
Reader Services
Ann Morris
Advertising Enquiries
Glyn Smith
Phone (02) 9939 3295
Mobile 0431 792 293
glyn<at>siliconchip.com.au
Regular Contributors
Brendan Akhurst
Rodney Champness, VK3UG
Kevin Poulter
Stan Swan
Dave Thompson
SILICON CHIP is published 12 times
a year by Silicon Chip Publications
Pty Ltd. ACN 003 205 490. ABN 49
003 205 490. All material is copyright ©. No part of this publication
may be reproduced without the written consent of the publisher.
Printing: Hannanprint, Noble Park,
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Distribution: Network Distribution
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Subscription rates: $97.50 per year
in Australia. For overseas rates, see
the order form in this issue.
Editorial office:
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Postal address: PO Box 139,
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Phone (02) 9939 3295.
Fax (02) 9939 2648.
E-mail: silicon<at>siliconchip.com.au
ISSN 1030-2662
Publisher’s Letter
Australians’ knowledge of science
is abysmal
For a long time now, we have been very concerned
about the standard of teaching science in Australia and
indeed, the low priority it appears to get in Australian
secondary schools. Never mind the fact that Australian scientists like Brian Schmidt, Peter Doherty and
Elizabeth Blackburn have recently won Nobel prizes for
their work because the average Australian’s knowledge
of science is abysmal. In fact, if you asked the average
Australian who these three scientific giants were, you would get a blank stare.
Sure, Australians love technology but very few have more than a superficial
understanding of how it works. I was reminded of this recently when I watched
a program on Stephen Fry’s “100 Greatest Gadgets”. Stephen Fry is no mean
intellect himself but he still managed to trivialise the whole 2-part program
and ended by naming the top “gadget” as the cigarette lighter! As he waded
through the list, which seemed to have no increasing significance in scientific
development, it occurred to me that neither he or most of the (likely limited)
audience would have much ability to explain how any of them worked. How
depressing!
But even more depressing is an article in The Australian newspaper on
Tuesday, July 10th, on the new syllabus for physics, chemistry and biology for
Years 11 and 12. Just read this quote from a statement introducing the syllabus:
“Science is a social and cultural activity through which explanations of
natural phenomena are generated.”
“Explanations of natural phenomena may be viewed as mental constructions
based on personal experiences and result from a range of activities including
observation, experimentation, imagination and discussion.
“Accepted scientific concepts, theories and models may be viewed as shared
understandings that the scientific community perceive as viable in light of
current available evidence.”
Well, what a lot of meaningless, mealy-mouthed, politically correct drivel!
In fact, it is just drivel. If that is how the syllabus authors regard science,
then heaven help us. They clearly have no concept of what science is about
or how it has developed over centuries. It is just this sort of thinking which
is so prevalent in the so-called consensus on global warming, being that the
“science is settled”. It isn’t and it probably never will be.
Thankfully, this vacuous view of science outlined by the Queensland Studies Authority was rubbished by the Australian Council of Deans of Science,
representing the heads of science faculties in Australia’s universities. Their
language was not as strong as mine but at least it was along the same lines. We
need a much more realistic view of the importance of science and its teaching.
My attitude to science is this: if you don’t understand basic science, you
cannot have any understanding of the environment around you. If you do not
understand science, you cannot understand how any of today’s technology
works. If you don’t understand science, you are utterly reliant on other more
educated individuals to ensure your survival in the modern world.
If you don’t understand basic science, you might just as well be living in the
middle ages! But with the wonderful resources of the internet, not understanding basic science is not a matter of lack of intelligence – it is laziness.
Leo Simpson
Recommended and maximum price only.
2 Silicon Chip
siliconchip.com.au
MAILBAG
Letters and emails should contain complete name, address and daytime phone number. Letters to
the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the
right to reproduce in electronic form and communicate these letters. This also applies to submissions
to “Ask SILICON CHIP” and “Circuit Notebook”.
Comments on Publisher’s Letter
in the June issue
With respect to the Publisher’s Letter in the June 2012 issue, I totally
agree with his comments about poor
rear vision in many of today’s cars.
It’s worse than some cars back in the
1950s. Best vision we have ever had
was a 1982 Toyota Corona and a 1983
Fairlane. You could see everything.
I was intrigued with the letter from
Hans Moll entitled “LED replacement
lamps work well” and his hassles with
interference from dimmer-controlled
lights. He bemoaned the fact that “No
one has any suggestions as to how to
overcome this interference”.
What? No-one? This problem is as
old as Methuselah and its due largely
to the minimalist design of the dimmers. As I recall, Electronics Australia
did a design some time back to correct this and many years ago when I
was building Triac-controlled speed
controllers for drills, the addition of a
choke and some capacitors cured the
problem. How about re-publishing the
design for old-time’s sake?
This brings me to a big whinge.
We went through a period where the
Government flogged us to death about
C-Ticks etc so that we would have
School crossing lights
should be much cheaper
I was the original researcher who
assessed the initial school speed
zone signs for the NSW Roads &
Traffic Authority. Together with my
colleague, Chris Cunningham, we
carried out what proved (when we
went to publish) to be the largest
study in the English speaking literature. We thought it was a pilot.
The RTA never found out we were
a geographer and a town planner. I
could talk the engineer speak!
Our findings were that at 50%
of the sites studied we observed a
statistically significant reduction in
speed during the time of the signs’
operation. In 50% of those cases,
4 Silicon Chip
equipment that would be certified not
to emit any EMI. I have DVD and CD
players which emit so much EMI that
I can not use an AM tuner in the same
cabinet when they are on but not fully
in use. They have a C-Tick though! As
usual, it’s another useless Government
initiative.
In the “Ask SILICON CHIP” pages of
the same issue, you had a brilliant response to R. P. Horley, in the UK, about
his “improvements” to the Ultra-LD
Mk.2 Amplifier. Apart from the issues
you referred to, what about the speakers in use to audition the changes,
how good are his ears, etc, etc? Tests
such as he seems to have done cannot
detect the change he is talking about;
it is humanly impossible.
Keep up the good work.
Ranald Grant,
Bellbowrie, Qld.
Soldering SMDs is
straightforward
The Universal PIC/AVR Programming Adaptor Board featured in the
May 2012 issue is the first major SMD
based project I have tackled and I have
now assembled all of the SMDs on the
top side of the board and found that
with patience and the described SILIthe reduction was 10km/h or more.
So, they work.
We examined the semiotic literature and formed the view these
were seriously bad signs. We recommended flashing lights, with the
signs simply reading “40km/h when
flashing”.
My background (way back when)
is as an appliance repair technician.
I built a “proof of concept” model
using the solar cell from my electric
fence (I lived in the country) with a
small sealed lead acid battery and an
on/off switch operated by a modified
remote control garage door opener.
The concept was simple: kids
around, they switch it on; no kids,
switch it off.
CHIP technique, I am more than
happy with the soldering outcome.
I would like to pass onto other readers that this project is not as daunting
as it first may seem. Where in the past
I have tended to shy away from SMD
projects, I now look forward to future
offerings from SILICON CHIP.
Warwick Guild,
Dunedin, NZ.
CON
Cameras will never replace
reversing mirrors
In answer to the Publisher’s Letter
in the June issue and his suggestion
that video cameras could replace rear
view mirrors, this is why they should
be retained. First is safety. Mirrors are
unaffected by power failures. Mirrors
have an MTBF of decades. A full set
of mirrors is effectively a “dual redundant” system.
Mirrors encourage driving skills, not
technological laziness. I prefer to drive
manuals for the same reason. Finally,
mirrors will always be cheaper than
a dual-redundant triple camera and
screen system.
Fabian Stretton,
Surrey Hills, Vic.
Comment: many cars now on sale
come with a video screen and often a
I figured I could build prototypes
for testing on-site for about $1200
installed (two per school of course)
but no interest.
I commend Peter Olsen for “having a go” on this. Having had the
RTA for a client a couple of times
now I know how he feels. Let me
tell you about a road connection to
a park we had trouble getting when
I worked for a council. Wal Murray
(then Minister for Roads) fixed that
one in about 30 minutes.
I feel intensely frustrated that lives
have been lost because we could
not take the step of cheap, effective
signs.
Angus Witherby,
Mordialloc, Vic.
siliconchip.com.au
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August 2012 5
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r
Mailbag: continued
School flashing lights: the
simple English approach
Following the article on Peter
Olsen and his Flashing School
Lights in the July 2012 issue, I keep
seeing school lights everywhere I
drive now! I thought you may be
interested in the lights and prices
most commonly used in the UK.
The quote is for “one off”, the
new LED ones, but many schools
still use traditional bulbs, turned
on manually by magnet (off/on
timer) and still available new for
the princely sum of £126 (AUD200)
each. Have a look at: http://www.
simmonsigns.co.uk/School-Crossing-Patrol-Signals.htm
They are normally mounted
vertically on the pole below the
sign (I guess you know why) because (1) they are then at a better
height (driver head height) and (2) vertically on the
pole means they are easily rotated to point directly
at the driver.
Clive Seager, Technical Director,
Revolution Education Ltd, Bath, UK.
camera. Adding a few more could well be cheaper than
external motor-driven rear view mirrors, particularly those
that fold into the side of the vehicle.
Big organisations produce
expensive solutions
With respect to the RTA and its expensive flashing lights,
I’ve worked in big organisations. Over and over I saw
that phenomenon you describe where the RTA insisted
on installing flashing lights that cost $58,000 rather than
Peter Olsen’s ones that cost $1400. There’d have to be a
committee of all the “stakeholders” and endless meetings
where everyone around the table would demand some
feature relating to their area of responsibility and none
would concede it wasn’t vitally important. And no-one
around the table considered the cost. That was someone
else’s problem.
Everywhere you look in the technology area you see
there is one product targeted at consumers that just gets
on and does the job the customer wants, and another for
“enterprise” customers that costs a number of times as
much that is loaded up with an endless list of rarely used
and/or largely useless features that end up making it harder
to use and less reliable.
That’s what scares me about the NBN. I look at the unit
that is being installed at each premises and it was obviously
designed by exactly that sort of process. No-one at the table
considered the cost to be their problem and no-one spoke
for the customer and what they want.
6 Silicon Chip
siliconchip.com.au
Halogen incandescent
lamps are available
On page 8 of June 2012 “SILICON
CHIP” there is a letter referring to the
proposal by the Howard government
in 2007 to ban incandescent light
bulbs. As far as I know, incandescent
light bulbs have not been totally
banned in Australia or anywhere
else. Have a look in your local hardware store.
What has changed is that incandescent bulbs with an efficiency
level of less than 15 lumens per
watt (lumens/watt) are rapidly being
phased out. Lumens are a measure of
light output and watts are a measure
of energy input. For comparison, a
compact fluorescent produces about
50-75 lumens/watt and the latest
LED bulbs up to 100 lumens/watt.
A 100% efficient light bulb would
produce 683 lumens/watt. So the 15
lumens/watt limit can be interpreted
as meaning all light bulbs must have
an efficiency of at least 2.2%.
The 15 lumens/watt requirement
has led to restrictions on the sale of
most downlights as well as the traditional tungsten incandescent bulbs.
These restrictions do not apply to
specialist lights where there is no
alternative, for example oven lights.
Halogen-filled incandescent bulbs
are available for those who wish to
continue to use an incandescent bulb.
The following site has details of available incandescent bulbs within Australia: http://reg.energyrating.gov.
au/comparator/product_types/40/
search/comprehensive/?wrapper_
search=&lamp_type
The reason why incandescent
bulbs containing a halogen gas are
more efficient is interesting. Like
the traditional light bulb, a halogen
lamp is made of a tungsten filament
encased inside a transparent envelope. In a traditional element, the
tungsten gradually evaporates and
deposits on the glass. Eventually,
It is a phenomenon that becomes
worse the more people specialise, as
generally happens in our increasingly
expert-driven society but especially
in organisations that are big enough
that responsibility for both success
and failure is divided up. The more
siliconchip.com.au
the filament breaks. But by adding a
small amount of a halogen gas this
“evaporation” can be reversed.
Halogens combine with tungsten
if the temperature is sufficiently
high. By including a halogen gas,
for example bromine, the generated
tungsten vapour is recycled back to
the filament rather than simply being deposited on the inner walls of
the envelope. Almost total tungsten
recycling occurs if the glass envelope
can be kept at 250°C but this requires
special quartz glass and care with
bulb handling. Domestic replacement halogen bulbs run with slightly
lower temperatures and so can be
handled like traditional light bulbs.
An incandescent bulb filament is
by far the hottest object we are ever
likely to experience. A halogen light
bulb filament runs at around 3100K,
over half the temperature of the Sun’s
surface. This is the reason halogen
bulbs give a good white light that
is not too far from the natural light
emitted from the 5500K surface
of the Sun. Traditional bulbs are
slightly cooler, at around 2800K. For
temperature comparison, steel melts
at about 1800K, titanium at 2000K.
In summary, incandescent bulbs
are still available. While government
regulation may be hastening the
replacement of incandescent bulbs,
a greater threat to their long term
survival comes from technological
change, in particular the newer LED
lights.
John Cameron,
Roseville, NSW.
Comment: it seems that the widespread availability of halogen lamps
in standard bulb sizes is a recent
development because incandescent
lamps largely disappeared from
hardware shelves in the years after
2007. In any case, the halogens
are much more expensive than the
standard incandescent lamps they
have replaced.
people have jobs, salaries, positions
and power based on a small area of
expertise, the most convinced they become that that area is more important
than everyone else thinks it is. They
lose the ability to get the big picture
in perspective.
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www.eraudio.com.au
August 2012 7
Mailbag: continued
Helping to put you in Control
Control Equipment
3A Stepper Motor
Controller & Driver
Send commands via
SPI port to move the
motor a set number of
steps. Acceleration
profiles to prevent jerky starts and stops.
SFC-075 $37.00+GST
D15 to Screw Terminal
Card Allows you to easily
connect to I/O through a
high density D15 connector. D9,D25 and RJ45 cards
also available. DIN Rail
mounting an option.
DTC-0151 $39.00+GST
Magnetic Temperature
Sensors Measure the
temperature of steel
surfaces using these
RTD and K thermocouple sensors. Range –50 to 200degC
CMS-017 $77.95+GST
Temperature Controller.
The N323 has 3 relay outputs for heating, cooling
and alarm applications.
JKT T/C and RS485 Modbus communications for monitoring and control.
CET-0051 $109.00+GST
Head Mount Signal Conditioner Measure temperature of RTDs and thermocouples. 4-20mA output
and LCD display.
AXB-201 $79.00+GST
Large Process Display
Can accept RTD, Thermocouple, 4-20mA and
load cell signals. Fitted
with 5 digit 56mm LED
display, Analog retransmission and Modbus communications
IPI-103 $399.00+GST
Flow Meter/Switch
A programmable flow controller designed for use with
low-viscose clear or translucent liquids. Features 1%
accuracy and open collector
alarm output.
CMS-400 $299.00+GST
Contact Ocean Controls
Ph: 03 9782 5882
www.oceancontrols.com.au
8 Silicon Chip
Applicable standards for program
loudness measurement
In recent months, your Mailbag
has had several letters which have
commented on the problems of
loudness and especially level differences between broadcast adverts
and program content or between
different channels. None of your
correspondents seem to be aware
that in the past couple of years, this
problem has been given considerable attention from various related
professional standards committees.
In particular, the ITU (International
Telecommunication Union) and the
EBU (European Broadcasting Union)
have done a lot of work.
Realistic and practical standards
have now been defined for measuring perceived program loudness, and
procedures for handling materials
from different sources with and
without loudness metadata. The ITU
got the ball rolling a few years back
with exhaustive listening tests and
refinement of measurement algorithms, to produce the ITU BS.1770
standard for loudness metering – see
http://www.itu.int/dms_pubrec/itur/rec/bs/R-REC-BS.1770-2-201103I!!PDF-E.pdf
The EBU weighed in with recommendations on the implementation
of systems to use this. A short over-
It is why big organisations, despite
their supposed “economies of scale”,
almost invariably produce products
that cost more than small ones do.
Gordon Drennan,
Burton, SA.
Urns and oven should
be better insulated
I have just read about the effort you
put into reducing the amount of power
that your urn uses (Circuit Notebook,
page 60, July 2012) and it reminded me
of a bench-top oven we purchased, because the big glass oven in the kitchen
was too expensive to use for just the
two of us. My wife tried to bake a cake
in it but without much success and she
asked me to see if there was anything
wrong with it.
view and links to a bunch of relevant
documents is at: http://tech.ebu.ch/
loudness
The BWF (Broadcast Wave File)
standard has also been updated to
provide for embedding loudness
parameters in a soundfile’s header.
This enables processing systems to
read the file header and determine
what levelling and/or compression
is required for that item. I believe
similar work is also being done
for audio embedded in video and
streaming formats.
Practical loudness meters are now
available in either hardware-based
devices or software plug-ins from
various vendors.
Recent industry conferences have
featured workshops aimed at educating the engineers and management
at Australian broadcasters to work
through the implementation of these
standards.
How well and how soon these
recommendations are implemented
will depend on the particular organisations. Implementing the standards
generally requires some changes
to hardware/software and training
staff, so that can all take time, unless
the organisation has a strong commitment to the process.
Noel Bachelor,
Castle Hill, NSW.
I inserted a thermometer into the
oven to see if it actually reached the
temperature she required. Well, it fell
far short. I left it on for quite a while
and the elements (one top & one bottom) stayed red all the time. A quick
check with an ammeter showed that
they were pulling the rated current.
That meant the wattage of these elements was quite large enough for the
job, so what was wrong?
I just happened to touch the outer
case and got a good burn and I knew
what was going on. These ovens aren’t
made like the old ones which were
fully insulated; they just wrap a metal
case around the sides and over the top.
The back and bottom are just the walls
of the oven itself. I happened to have
some high-temperature insulation in
siliconchip.com.au
the shed so I enclosed the oven in
this, making a metal piece to cover the
back. I left the bottom as it was. I also
fitted a proper thermostat out of an
old oven so as to give a more reliable
temperature control.
The oven is now a much-used item
and does a really good job. Not only
that, you can’t get burned by the case
any more and as the elements cycle on
and off it must be using less power. Another thing is that in the warm weather
it must mean that the air-conditioner
has just that little bit less to do.
So if you can get a fully-insulated
urn, you will not only save on the
power that the urn uses but also on airconditioning costs in the hot weather.
What I would like to know is why they
stopped insulating things that get hot?
Ron Groves,
Cooloola Cove, Qld.
More on home solar
power system
This is a follow-up letter about
my experiences with my home solar
power system, as detailed in the Mail-
Low-cost, effective lens
for the LED Dazzler
I built the LED Dazzler (S ILICHIP, February 2011) when it
first came out and although it was
extremely bright the light output
wasn’t really usable. I recently stumbled upon some lenses for the STAR
P7 LEDs on eBay at two for $6.29. I
bought two lots and I fitted them to
two of the LEDs.
I had to do a small amount of filing to get the lens to sit flush onto
CON
bag pages of the September 2011 issue.
A couple of weeks ago the installing
electrician came to visit me with a new
DC isolator switch. He said that the
Electrical Inspector from the Queensland Dept. of Justice had contacted
him to say that the previous unit was
now the subject of a recall.
So he had procured a replacement
– this time another Chinese product
that he said cost him only $40. It is
branded Clipso, a spoof of our famous
Clipsal brand.
the metal PCB but it only took minutes. Now I have really usable light
output. I tried to take some photos
but they didn’t do the light output
justice. They can illuminate my shed
which is about 60 metres from my
house and I would not hesitate (if I
had to) to drive down the road using only these LEDs. These are only
cheap plastic lens and I wonder what
quality lenses would be like.
Tony Brazzale,
Lakes Entrance, Vic.
What’s concerning to me is that even
though I have made a formal complaint
to those inspectors, including a written
statement, I have never received any
written communications from them
and it is over a year since I made my
first complaint. Even more disappointing is that the installer told me that he
has overcome all of the problems that
I experienced in subsequent installations by doing the following:
(1) Supplies and installs a Germanmade inverter that has an internal iso-
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siliconchip.com.au
August 2012 9
Mailbag: continued
Highly priced power fuses
cannot improve sound quality
I saw this advert on eBay recently
and thought I’d send it to you so you
can publicly “rip into” this mob (if
you want to): http://www.ebay.com/
itm/ws/eBayISAPI.dll?ViewItem&it
em=150695403285&ssPageName=A
DME:B:EF:US:1123
It is incredible that people can get
away with such fanciful advertising
about something that has absolutely
lation transformer, so now he doesn’t
bother to put an earth wire to the solar
panels. He said this inverter cost about
$800. He must think that earth wire is
prohibitively expensive.
(2. He now splits the solar array into
two runs so that he can use a lower
power DC isolator switch. This presents another problem that seems to be
of no concern to him. If the customer
wants to generate power at the beginning and end of the day, it is necessary
to have as many panels in series as
possible to create a voltage higher than
that required to start the inverter and
to pump power into the grid because
that is what we are being paid for.
These two decisions on the part of
the installer highlight the absence of
a Certified Designer in the supplying
company. But according to the Clean
Energy Council, each supplier must
7”
no chance of providing the performance enhancements claimed.
Peter Allen,
Tura Beach, NSW.
Comment: we have no doubt that
there are enough gullible people
“out there” to make such outrageous
advertising very worthwhile for the
promoter. Such are the consequences when most of the population have
little understanding of even the most
basic technology.
have one of those to ensure correct
design.
Anyway, it is all a bit academic now,
because the new Queensland Premier
has decreed that all new contracts for
the supply of renewable energy into
the grid will be at 8c/kWh instead of
the current 44c/kWh.
Chaim Lee,
Toowoomba Qld.
Inverter generators confuse appliance
with switchmode supplies
In reply to Ron Goodwin’s letter
about mains AC waveform distortion
in the July 2012 issue (page 4), I have
a possible explanation on why some
portable generators have trouble with
appliances with switchmode power
supplies.
Ron mentions cheap generators
having problems with “filthy output”
but I believe this is a “red herring”.
The real culprits, and he notes this
implicitly, are the rather expensive
generators (non-inverting and probably inverting as well) with high-tech
controls and AVRs.
Some people might pay more to
have high-tech equipment just for its
own sake but most of us pay extra for
what the high-tech gear can do, not
for what it is. As such, these types of
generators are claimed and expected
to be more efficient (cheaper to run),
more green (save the environment),
more convenient (we are a lazy lot)
and less intrusive (keep the noise and
the weight down) than the run-of-themill type.
Therefore, if there is no load on the
generator it can sense this and stop
producing a nominal voltage waveform. This can, depending on the
design, reduce the off-load running
costs for fuel and maintenance as well
as lowering ambient noise levels. In
a lot of normal usage, the generator
is actually off-load for a considerable
percentage of its working cycle, so
significant savings can be made over
a generator with a more conventional
AVR.
Of course, the generator will excite
its fields slightly and regularly during
this off-load time and sense the current
draw to determine if a new load has
been added. The problem is that the
high-tech appliance with electronic
control circuits and/or switchmode
power supplies requires close to the
Digital Storage Oscilloscopes
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10 Silicon Chip
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full nominal voltage before allowing
the appliance to be fully powered up
and functional. Thus we have a classic
“chicken or egg” situation.
The generator won’t supply nominal power until a load is present and
the load won’t become present until
the nominal power supply is available. The simplest and best available
workaround is to introduce a plain,
low-tech resistive or inductive load
that alleviates this paradox.
I must state this is only a theory
as I don’t have access to the intricate
details of modern high-tech portable
generators or modern high-tech appliances and how they may interact with
each other. But casual observations of
cause and effect seem to agree with
my theory.
Trevor Krause,
Gympie, Qld.
Fitting an oxygen sensor
to a Land Rover
In the “Ask SILICON CHIP” pages of
the June 2012 issue there was a query
from M. M. regarding fitting heated
oxygen sensors to an older model
Land Rover Discovery. Although the
writer does not indicate which model
he has, I assume that it is probably of
similar vintage to my 1995 Discovery.
If so, then M. M. should be aware of
the following points:
The Lucas 14 CUX ECU that is
most probably fitted to his vehicle
can accept oxygen sensor inputs and
continued to be used in later models
with oxygen sensors and catalytic
converters. Apart from any ECU socket
shortcomings, the only change required to the ECU to enable oxygen
sensor inputs is to change the value of
the “sense” resistor which selects an
alternate operating program that looks
for oxygen sensor inputs.
This ECU was designed to operate
with Titania oxygen sensors which
have a sharp resistance change at
stoichiometric operation, rather than
the sharp voltage change of the much
more common Zirconia type sensor.
The two are not interchangeable and
the voltage output of the wideband
oxygen sensor would also be unsuitable as an input for an ECU designed
for Titania sensors.
The heater incorporated with the
Titania sensors specified for the Discovery does not have any special control requirements and can simply be
connected to the appropriate terminals
in the wiring loom. The addition of
Titania oxygen sensors to a pre-cat
alytic converter on the Discovery is
certainly possible and can significantly improve fuel economy but it is
not for the faint-hearted.
An internet search on the Lucas
14CUX ECU should provide M. M.
with some additional background.
Don Brown,
Beachmere, Qld.
Good home wanted
for EA magazines
Just a note to let your readers know
Power filter can
reduce clock gain
I noted that there was discussion on “Clock Radios Gaining
Time” in the Mailbag pages of the
July 2012 issue. I have recently
had solar power installed and
also noted that a previously accurate clock radio was gaining
six minutes each day.
As a starting point, to eliminate this time gain, I installed
a line filter & conditioner I had
previously constructed. Initial
results indicate that there is now
only a one minute gain per day.
It’s not a total fix but this result
may give a clue as to what the
interference is.
Gordon Charlton,
Sunbury, Vic.
that I am about to finally clear my collection of Electronics Australia magazines. I realise that they are probably
of very little use to anybody else but I
would rather give them to a good home
than just throw them away.
They are free to anyone that would
like them but they will need to be
picked up as they are quite heavy and
would be very expensive to transport. I
have all copies from May 1967 to July
1990 inclusive.
Steve Tobin,
6 Endeavour Ave,
Orange, NSW.
SC
Phone 0429 339 867.
5
MATRIX
FLOWCODE
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don’t have time to become expert
microcontroller programmers.
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siliconchip.com.au
August 2012 11
Nissan’s new LE F –
On June 15, the much-anticipated Nissan LEAF 100% electric vehicle
went on sale in Australia. Not co-incidentally, this was also the day
it was introduced to the media – including SILICON CHIP. We had a
good look at the LEAF and took it for a reasonable (if all-too-short)
drive. Were we a little impressed? No way! We were very impressed!
Review by Ross Tester
W
e’re going to resist the puns like “turning over a
new leaf” and so on – we’ll leave those to other
media. We were more interested in the technology behind this vehicle and just how it can fit in to our
readers’ lives.
According to Nissan Australia’s Managing Director,
the LEAF will be slow to take off (they’re only expecting
to sell “hundreds of units” in the first year, compared to
thousands of their conventionally-powered models) but
eventually it, or its successors, will become the mainstream motor vehicle for many, perhaps even most, urban
Australians.
This forecast mirrors the LEAF experience in the US,
where it has been on sale since late 2010. First month
sales were just 19, with 9674 sold in 2011 and 2613 sold
between January and May 2012.
We’re talking years away of course. Like any new technology, there will be the “early adopters” but convincing
12 Silicon Chip
the average Australian driver to accept electric vehicles
is not going to be an easy sell. Especially as they are significantly more expensive than petrol or Diesel-powered
counterparts.
But first, we’re going to nip some anticipated criticism
in the bud.
When we reviewed the Toyota Prius/Honda Insight
hybrids and more importantly the Mitsubishi i-MIEV (December 2001 and February 2011 respectively) we received
some rather scathing correspondence, not criticising our
reviews as much as the technology itself.
There were two sides to that cricitism and by extension,
we believe some readers will apply them to the LEAF as
well.
Green machine?
First was the condemnation of the electric vehicle’s
“green” credentials but most strident was the criticism
siliconchip.com.au
– 100% EV
of their range. “Who would want a vehicle which only
travelled 100+ kilometres before needing recharging and
even then had trouble keeping up with traffic on a freeway,”
they asked.
Let’s answer that question first: Considerable research
by various bodies around the world has shown that the
vast majority – 80% in fact – of urban commuters drive
less than 100km each day. That includes Saturdays and
Sundays, when they might be running the kids to sport,
going on a picnic, to church, etc.
Indeed, Nissan’s “actual use” figures from 7,500 LEAFs
in use in the USA reveal the average vehicle drove 60km
per day with the average trip 11km in length. (We’ll look
at just how Nissan gathered those figures shortly).
Therefore, contrary to the naysayers, electric vehicles are
very well suited to the vast majority of urban commuters!
Nissan’s Australia’s CEO Bill Peffer put it best: “When
you come home from work, you plug in your mobile phone
to charge it overnight. Nissan LEAF owners will also plug
in their electric car to charge it overnight . . .”
And don’t worry about keeping up with the other traffic – with a top speed of 140km/h and great acceleration,
you’d be passing most of it. Just watch out you don’t get
pinged for speeding!
Then comes the next (inevitable!) somewhat derisory
question: “What happens when you want to go on holidays.
You’re going to need a very long extension cord, ha ha!”
Again, this demonstrates a total lack of understanding of
typical Australians’ changing holiday habits. These days,
they’re much more likely to fly to their destination and if
needed, hire a car, 4WD, or whatever.
You’d hardly want to cram all the kids, luggage and so on
into what amounts to a small car to travel from Melbourne
or Sydney to the Gold Coast, petrol or electric powered.
If you really must drive distances, then an electric car
is probably not for you (at least yet!).
As far as size goes, think Mazda 3 or Toyota Corolla and
add a little.
Green power
Correspondents also challenged us on the green credentials of electric vehicles on a number of fronts: the energy
required to produce the batteries, motor and so on (of
course, no energy at all is required to produce an internal
combustion engine) and again, more important to some,
the greenhouse gases produced in making the electricity
to charge the batteries.
To be brutally frank, we dismiss these criticisms out of
hand. Despite our current government’s insistence that we
humans are nasty people for daring to use coal-dependent
electricity, we all know that electricity must be produced
this way for the foreseeable future (we’re talking decades
here at least) for the vast majority of “base load” power.
Turning back to charging electric vehicles, it is antici-
Inside the LEAF it looks much like any modern
5-door hatch . . . until you start looking a bit closer.
Things like that “gearstick”, for example. And then if
you look at the instrument panel and centre console
display, you really start to see some differences!
siliconchip.com.au
August 2012 13
A cut-away of the LEAF showing the charging ports (front) with the motor immediately behind, the under-floor batteries
and the 3-phase controller immediately behind. On top is the solar panel which keeps the 12V system battery charged.
pated (as mentioned before) that the vast majority will be
charged overnight, using predominantly off-peak power.
Incidentally, Nissan have gone out of their way to make
the LEAF as environmentally friendly as possible, with
recycled material used extensively in manufacture and the
vast majority of the vehicle is itself recyclable.
OK, let’s look at the LEAF
First of all, that name: it apparently stands for Leading,
Environmentally friendly, Affordable, Family car (though
you won’t find that in Nissan literature).
It’s not Nissan’s first electric car – in fact, they’re quick
to point out that the company’s electric vehicle pedigree
goes right back to post-WWII Japan with its oil shortages.
In the intervening 65 years various electric vehicles have
been made, including some concept cars which never saw
the production line.
Nissan claim the LEAF is the world’s first purpose-built,
mass-produced all-electric car (one wonders where they
place the Mitsubishi i-Miev which predates the leaf by many
months). It’s 100% electric, unlike several hybrids (electric
cars with petrol engines also supplying power) and others
like the soon-to-be-released Holden (Chevrolet) VOLT – an
electric car with back-up petrol generator.
As such it can boast not low emissions, but ZERO emissions. There is no tailpipe/muffler because there is no
engine exhaust.
It’s a five-door hatch, not too dissimilar to many other
petrol hatchbacks on the road today. But there are also
subtle (and not-so-subtle) differences. Again, Nissan point
out that the LEAF was designed “from the ground up” to
be an electric car, not an adaptation of an existing petrol/
Diesel-powered vehicle.
It’s claimed to have room for five people but in our test
drives we sometimes had four adults in the car – and the
fifth person would have had to be a leprechaun. It might
just fit two adults and three kids, but you wouldn’t want
14 Silicon Chip
to drive for too long. Oh, you can’t anyway!
There is no gearbox as you are used to. You simply have
the choice of forward and reverse, selected by a computer
mouse-inspired control knob.
There is also no ignition switch – as long as you have
the RFID “key” in the car (eg, in your pocket) all you do is
push the engine start button and the vehicle energises after
a second or so with suitable chimes and so on. The engine
doesn’t exactly start – it’s ready as soon as you apply the
accelerator in the conventional manner.
And what acceleration! As you probably know, electric
motors develop maximum torque at virtually zero RPM.
So if you’re looking for get-up-and-go, the LEAF certainly
gets-up-and-goes. Performance has been equated with that
of a typical 3-litre V6 petrol-engined car.
In the drive, which took me from the launch at Little
Bay (SE suburbs) up towards Sydney city and back again, I
had no trouble at all in keeping up with other traffic – and
could easily overtake when I wanted to.
While on the subject of the drive, I have to admit that I
found the lack of engine noise somewhat disconcerting for
the first few minutes but then it was ignored. I noticed it
again (or lack of it!) when stopped at traffic lights but I’d
suggest this problem is one I’d easily get used to.
Wind noise was perhaps more noticeable than in most
cars but this was arguably because there was less engine
noise. But it’s not something I found annoying or even
intrusive.
An aside: the Nissan technical guru who accompanied me
on the drive explained that the headlights were especially
sited to break the laminar wind-flow so that it went around
the external rear-vision mirrors, thus reducing their noise!
While a small-ish car, it has a healthy 2700mm wheelbase so it certainly doesn’t jump around like a jackrabbit.
Overall length is 4445mm, width 1770mm while the
height is a quite low 1550mm. Nissan explained the design
has been optimised for low drag coefficient in order to get
siliconchip.com.au
the maximum range from each charge.
As such, the front is quite low and ground clearance also
relative low at 160mm. It’s heavy for a small car at over
1500kg, explained to a large extent by the weight of the
batteries and motor. Maximum payload is just on 400kg.
Batteries and motor
Nissan and its partners have spent most of the development time of the LEAF in researching and producing batteries. The LEAF is a far cry from their post-war “Tama”
electric car – it used lead-acid batteries, had a range of
65km and a top speed of 35km/h.
By contrast, the LEAF uses a purpose-built 24kWh Li-ion
battery comprising 48 modules, each of four cells. Each
person I asked at the LEAF launch gave me a different battery voltage and no-one could tell me how the cells were
connected but I’m guessing that they are arranged as two
paralleled banks of 24 cells, giving the total battery voltage
about 360V (ie, 4 x 24 x 3.75V = 360V).
In contrast to most other electric or hybrid vehicles,
which often have the batteries in the boot space or under the
rear seat, because the LEAF was an all-new vehicle Nissan
had the luxury of placing the batteries wherever was best
suited. This turned out to be underneath the floor, right in
the middle of the vehicle. It was made even easier with no
prop shaft or exhaust pipe to worry about.
Battery life
There’s been a lot of (mis)information on many websites
and even some media about battery life of electric vehicles.
“Expect to replace the batteries in 3-5 years” was a comment I read more than once.
When queried, Nissan maintain they expect the LEAF
batteries to have a life of at least 8-10 years and were anticipating even more – perhaps 15 or so.
In fact, the LEAF in the USA has an eight-year/160,000km
warranty on the batteries and they wouldn’t do that if they
weren’t confident of their life predictions. I’m presuming
it will have the same warranty here.
Battery life depends on how you drive and most importantly, how you charge. If you continually rely on the fast
chargers that are (very) slowly springing up around major
cities, your battery life could be significantly curtailed.
But if you use the relatively slow charge from a 230V/15A
outlet, drive smoothly and not discharge the batteries too
far before charging, then you could easily meet or exceed
Nissan’s expectations.
If and when required, a battery changeover would set you
back somewhere around $10,000 at current rates but given
the state of battery development and increasing volumes of
production, could be significantly lower in ten years or so.
Before concluding the discussion on the batteries, it’s
interesting to note that the LEAF also has a 12V lead-acid
battery in the engine bay which supplies power to all the
low-voltage vehicle peripherals.
We have to assume that it is also kept charged via the
main HV battery but the Australian version of the LEAF
also has an integral solar panel in the rear spoiler which
also charges the LV battery when the vehicle is parked
outside in daylight.
The motor
A 3-phase 80kW synchronous AC electric motor provides
siliconchip.com.au
THE CURRENT STATE OF EV PLAY
True EV (ie, 100% electric vehicle)
Mitsubishi iMiev – $48,800 Available in Australia now
(limited dealerships)
Nissan LEAF – $51,500
Available in Australia now
(limited dealerships)
Tesla – up to $205,000+
Various models available USA,
Japan, Europe now.
Limited availability in Australia
Renault Fluence ZE – $TBA To be launched late this year
(has swappable battery).
Ford Focus EV – $TBA
Limited availability in USA now,
Australia “probably 2014”
Hybrids (ie, combined electric/petrol)
Toyota Prius –
3rd version now available in Aust.
EV version now available in the US.
Toyota Camry –
Available in Australia now
Lexus Hybrid –
Available in Australia now
Honda (Insight, Civic, CR-Z) – Available in Australia now
Holden Volt (HEV) –
Available in USA (Chevrolet Volt)
since Dec 2010; Australia
scheduled release Oct/Nov 2012
front-wheel-only propulsion with 280Nm of torque. This is
powered from the battery bank by a DC/AC inverter with
computer control. The motor is not too dissimilar in size
to a 4-cylinder petrol engine (see photo) and occupies the
majority of the engine bay.
The motor spins out to a maximum 10,390 RPM with a
single-speed gearbox ratio of 7.9377:1
Charging
Two charging points are provided on the front of the
LEAF. One is for a standard 230VAC 15A outlet (which
results in a 14 hour full charge) and the other for a 400V
“fast charge” (four hours).
The car itself has both a 3.3kW normal and 50kW fast
charger on board. The fast charger will charge the battery
to 80% full within 30 minutes.
At the time of writing, there were 16 fast-charge points
around Sydney (and the car will tell you where they are).
Normally there is a small charge (I believe between $2
and $10) to “fill” the car – a lot less than the $50-$70+ it
now takes to fill an average small car petrol tank.
However, in the US, where the LEAF (and other electric
cars) have been available now for over a year, many shopping
centres and other venues have been putting in fast-charge
points and/or standard power outlets (with appropriate
electric-vehicle-only spaces) which are free – they figure the
longer they can keep you there the more you’ll spend inside!
August 2012 15
You can get a fast charger for your home – estimated price
including installation would be around $2200 or so but I
understand 3-phase power is required. If you need a 15A
outlet and dedicated circuit installed, that would probably
cost you about $250.
According to Origin Energy, the NSW electricity supplier
whom Nissan have teamed with for LEAF energy supply,
many businesses have, or are considering converting their
local fleets to EV and are installing charging points for
LEAF - ZE0 – Specifications
Elec. Motor type
3-phase AC synchronous
employees to use (again, free of charge).
The LEAF also features “electrically-driven intelligent
braking” which is known to you and I as regenerative
braking. Travelling downhill, energy is recovered from the
engine to recharge the batteries. It’s progressive – it wasn’t
easy to tell when regenerative braking kicked in nor, when
I applied the footbrake, when it changed from regenerative
to power-assisted mechanical.
Up to 80% of the energy of braking, normally lost as
heat, is recovered.
Electronic “smarts”
Kerb weight min./max
1525/1567kg
Gross vehicle Weight
1965kg
Maximum payload
395kg
Maximum axle load FR
1020kg
The LEAF is much more than a battery powering an electric motor to drive wheels. No-one at the launch could tell me
how many CPUs there were in the car but my guess would
be dozens – much more than in a conventional vehicle.
First of all, there is all the battery monitoring and range
computing. It can not only tell you the state of battery
charge (a la the petrol fuel gauge) but from this, and the
way you are driving, tell you how far you can go on that
charge – and how much further you can go if you switch
to the “eco” mode.
In this mode, acceleration is not quite as brisk (although
plenty for 99% of circumstances). But if you happen to see an
18-wheeler barrelling through the intersection towards you,
plant your foot and the mode changes back immediately.
Battery monitoring also controls how the car will drive.
At normal levels, you get normal control but when it drops
down to about 40%, the car starts progressively shutting
down power hungry devices such as the air conditioner/
heater. You also start to get warning messages via the console.
Ignore them and at a much lower charge (5%?) the car
enters limp-home mode which (hopefully) will get you to
a charging station (or home).
Keep driving, and the point is reached where the battery
is regarded as flat. The car will keep going a short distance
but at a dramatically reduced speed – it’s intended to allow
you to get off the road and perhaps around a corner before
giving up the ghost completely.
If you’re stupid enough to get this far (which is about the
same as running out of petrol in the middle of the Harbour
Bridge!) you’re not going to be able to hitch a ride to a servo
and fill up a can. You’re going to need a tow truck unless
you can find a 15A outlet very close and wait for a charge.
Maximum axle load RR
995kg
The amazing dash display
Max. engine power
Max. torque
80kW / 2730-9800 RPM (min)
280Nm / 0-2730 RPM
Max RPM
10,390
Battery Type
Laminated lithium ion
Battery Voltage
360V
Battery Capacity
24kWh
Number of cells
192
On-board chargers
Gearbox
3.3kW and 50kW
Single Speed Gear Reduction
Final drive ratio
7.9377
Driven wheels
Front
Suspension front
rear
Steering
Braking system
Independent Macpherson strut
Torsion beam axle
Electric power assisted
Regenerative - FR Ventilated Disc
Overall length
4445mm
Overall width
1770mm
Overall height
1550mm
Wheelbase
2700mm
Track front
1535mm
Track rear
1535mm
Electricity consumption
Range
Maximum speed
Acceleration 0 - 100 km/h
16 Silicon Chip
Integrated into the dash is a multi-function display which
has many levels of menu selection to set, well, you name it!
173Wh/km
175km
145km/h
11.9s
Built into the rear spoiler is a solar panel which keeps the
12V aux battery charged when the car is parked in sunlight.
siliconchip.com.au
A cutaway
diagram of the 360V
battery pack especially
developed for the LEAF. At
right is the 80kW electric motor, also purpose-built.
I noted a speedo/odometer, battery power meter, battery
temperature, remaining energy gauge, capacity level gauge,
distance to empty display (2 modes), Eco indicator and even
an outside temperature readout. (I’m sure there are more!).
It incorporates the 6-speaker entertainment system –
again, all touch-controlled – along with the integrated
GPS which allows the car to not only do all the things any
“normal” GPS does but also uses the info to map rangebefore-recharge in both normal and eco mode.
It also displays the rear-view camera which is fitted with
intuitive parking guides – lines which show you the vehicle’s
path (and obstacles) according to the direction of the steering wheel. Parking is therefore dead easy – not automatic,
as in some cars these days (including some other Nissan
models) but easy nevertheless.
And it also provides access to data to and from Nissan
Carwings.
Nissan Carwings
The Nissan LEAF is fitted with what amounts to a mobile
data phone, inaccessible to the owner (except for some incoming command “calls”, as we shall see) but with its own
SIM card and number. It cannot take or receive voice calls.
Every day, or every journey, this module “calls” the
very secure Nissan International Data Centre in Japan and
transmits data on the car’s operation – the distance it has
driven, vehicle parameters including state of charge, etc.
This information gives Nissan real-time data on every
LEAF sold anywhere in the world – hence the ability of
Nissan to be able to state, categorically, the average daily
travelling of all LEAFs in the USA (see above).
But it also has the potential to alert Nissan to any vehicle
problems long before the driver knows about them. Or it can,
for example, suggest to a driver that their style of driving
might result in shorter battery life!
This “service”, arranged through Telstra, has a subscription which is free of charge to the owner for the first three
years of ownership.
But there’s much more this data module can do. For
instance, it can enable the owner to remotely (via a mobile
phone app) tell the vehicle to start charging when electricity tariffs are lowest (who wants to get out of a warm bed
to turn the power switch on in the early morning?). This
can also be programmed via the extensive menu on the
dashboard LCD.
It can also be used to start the air conditioning at a certain
time so the driver gets into a warm (or cool) car – this while
siliconchip.com.au
still plugged in to the home charging circuit, so it doesn’t
use any vital battery charge. Again, you simply use the app
on your mobile phone. Of course, at the same time, climate
control is totally accessible from the centre console display.
About the only thing it doesn’t do (which to me was a
disappointment) was allow the ability to let the owner know
where the car was – for instance, if it had been stolen.
With the fully integrated GPS and the ability to communicate via the phone network I thought this would be
a natural – but the Nissan representative told me that they
had argued very long and very hard with the Privacy Law
authorities who continually kept putting roadblocks in
the way.
Driving it
All I can say is that it was a real pleasure. Comfortable
seats, smooth acceleration and braking (regenerative, of
course!) with cruise control, Bluetooth phone interface if
I wanted it and a driving position that allowed a superb
all-round view.
As I mentioned earlier, there was no problem keeping up
with city traffic on a variety of road types – about the only
criticism I had here was trying to take in all the wizardry
of the car while keeping an eye on the road!
It’s comforting to know that it has achieved the highest
level of car safety (five star, the first electric vehicle to do
so) and has extensive safety measures built into the battery
pack to isolate it in case of collision.
Would I buy one? If I had a lazy fifty grand or so lying
around, I’d certainly consider it. Unfortunately, I don’t! SC
Two charging ports are provided, one for 230V/15A home
charging and the other for 400V fast charging
August 2012 17
The latest thing in UAVs RPAs . . .
Remotely Piloted Aircraft (RPAs)
are on the threshold of a major
explosion in design, operation
and areas of deployment.
Leading the way in this
revolution is a style
of helicopter best
known as a
Quadcopter or
Multi-rotor Copter.
By Bob Young
MULTI-ROTOR
HELICOPTERS
I
n recent years, we’ve looked at Licence) but some classes of RPAs the review of the Parrot elsewhere in
several of the developments in will need to be controlled by those this issue) through to large, complex
UAVs (or now, officially called with the equivalent of either private machines intended for “serious” applications such as filming, surveying
RPAs) and the technology used in or commercial pilot’s license.
Fortunately, we believe that the and military uses.
these machines.
This type of vehicle is absolutely
However we are now entering a fun police won’t be looking at small
new era in RPAs, driven by the fact “hobby” quadcopters (which are ideal for use in urban environments
that in the USA the Federal Aviation referred to as SGMAs, or self-guided in that it is small, light, extremely
manoeuverable and relatively quiet.
Authority (FAA) has been instructed model aircraft).
There is a wide variety of these
by Congress to integrate RPAs into the
machines ranging from three rotors
US National Shared Airspace within Electric power
One of the machines featuring heav- through to eight or more rotors (even
90 days for emergency services and by
2015 for civilian use. This is expected ily in this new upsurge of interest in sixteen in the case of the man-carrying
to result in an explosive growth in the RPAs is the Electric Powered Multi- e-volo multi-copter, as we shall see).
rotor Helicopter.
Some have four arms with eight motors
use of RPAs.
They range from fun “toys” (see mounted in pairs, one above the other.
Here in Australia, CASA, having
Others have eight arms
originally led the world with
fitted with a single motor.
an operational regulation (isRPAs? What happened to UAVs?
Each has advantages and
sued in 2002), is now working
The ICAO (International Civil Aviation Organisation), the
disadvantages.
to bring an improved alignment
international aviation governing body, has recently “tidied
The media has recently
between technology advances
up” their acronyms and have decided that the terms for
discovered
the advantages
and aviation safety.
UAV operations are to be re-designated Remotely Piloted
One outcome of the legisla- Aircraft, or RPA. Thus we have RPL (Remote Pilot License), of these machines, leading
tion (due early next year) is that RPA (Remotely Piloted Aircraft) and so on. Over the years to a class of journalism
now entitled “Drone Jourcommercial RPA “pilots” will
we have gone from RPV to UAV to UAS and now RPA!
And don’t forget that CASA have decreed that only
nalism”.
need to be just that – licensed
A camera-equipped
pilots. Some will only need an commercial aircraft can be called “RPA” – hobbyist models
are to be called self-guided model aircraft, or SGMAs!
multi-copter which fea“RPL” ticket (Remotely Piloted
18 Silicon Chip
siliconchip.com.au
tured in an incident at the Christmas
Island Detention Centre last year
caused quite a stir and has since
brought to the fore all sorts of questions, not the least being privacy.
After taking photos of the Detention Centre, it crashed into the Indian
Ocean, giving rise to rumours that it
had been shot down.
The Author has since had it confirmed that it was not shot down but
even so, Christmas Island Authorities were indeed quite upset about
the whole incident, stating that “it
instilled fear for all concerned below”
with many of the detainees having
first-hand experience of what RPAs
are capable of doing from their years
in Afghanistan.
However there are even more serious aspects of “Drone Journalism”
to be considered. For example it is
now quite feasible for a quadcopter
fitted with a camera and real-time
video downlink to fly up to a window
and quite literally look through that
window – or indeed, if the window
is open, fly right through the window
into the room.
If some of the over-achieving drone
designers have their way, RPAs the size
of cockroaches or household flies will
be sitting on the wall or walking across
the desk listening in to any conversation in the room.
The Civil Libertarians are going to
go nuts over this stuff and it is here
now. However, for military people they
are a Godsend as they can completely
remove any mystery from entering
a room, peeking around a corner or
looking over a hill without risking
any soldier.
So what is a quadcopter and how
does it work?
Two early rotor craft: the Oehmichen No.2 (top), said to be the first successful
design and uderneath is the deBothezal machine developed for the United States
Air Service. Both are from the early 1920s. (Photos courtesy Wikipedia).
in the horizontal plane, stabilised the
machine laterally. Another propeller
was mounted at the nose for steering
with the remaining pair of propellers
being used for forward propulsion.
The aircraft exhibited a considerable
degree of stability and controllability
for its time and was the first helicopter
capable of reliably carrying a person.
The No.2 made more than a thousand
test flights during the middle 1920s.
By 1923 it was able to remain airborne for several minutes at a time, and
on April 14, 1924 it established the
first-ever FAI distance record for helicopters of 360m. Later, it completed
the first 1km closed-circuit flight by a
rotorcraft in 7 minutes and 40 seconds.
(Source: Wikipedia)
Dr George de Bothezat and Ivan
Jerome developed an aircraft for the
United States Air Service with six
bladed rotors at the end of an X-shaped
structure. Two small propellers with
variable pitch were used for thrust and
yaw control. The vehicle used collective pitch control.
It made its first flight in October
1922. About 100 flights were made by
the end of 1923. The highest it ever
reached was about 5m. Although demonstrating feasibility, it was underpowered, unresponsive, mechanically
complex and susceptible to reliability
Origins of multi-rotor
helicopters
The Frenchman, Etienne Oehmichen, experimented with full size
manned rotorcraft designs in the 1920s
and demonstrated the first successful
helicopter on February 18, 1921.
Among the six designs he tried, his
helicopter No.2 achieved considerable
success. This machine had four rotors
and eight propellers, all driven by a
single engine.
The Oehmichen No.2 used a steeltube frame, with two-bladed rotors at
the ends of the four arms. The pitch of
these blades could be varied by warping. Five of the propellers, spinning
siliconchip.com.au
Dave Jones, an American pioneer in multi-rotor craft whom SILICON CHIP
readers may remember from earlier model aircraft and radio control articles.
August 2012 19
Definitely not an RPA, nor a “quad”copter! This is the e-volo Multi-rotor, a 16-motor monster multi-rotor capable of
manned flight. Indeed the designer, Thomas Senkel, is shown here in the world’s first manned electric multi-rotor flight –
October 21 2011 in southwest Germany. (Photo: Wikipedia)
problems. Pilot workload was too high
during hover to attempt lateral motion.
(Source: Wikipedia)
An early pioneer in the model quadcopter field in America is Dave Jones
of AUAV in Florida USA (featured in
SILICON CHIP DSS [February 2009] and
Flamingo [June 2010] articles). Dave
experimented with R/C quadcopters
in 2003 and he is shown overleaf with
one of his quads. While flown quite
successfully as a radio-controlled
quad, Dave’s machine lacked the finesse found in modern quads.
Time and technology have combined
to completely sort out these shaky beginnings to the point where we now
see tiny little unmanned quadcopters
small enough to fit into the palm of a
man’s hand (usually referred to as na-
Here’s a DJI Flamewheel airframe with DJI 30A opto and DJI Nava stabilisation.
The motors are 928kV DJI. This quadcopter has the familiar “X” pattern of
rotors. The alternative is the “+” pattern which behaves quite differently. Both
are explained in the text.
20 Silicon Chip
nocopters), flying fully autonomously
in formation using swarm technology.
How times have changed.
Manned multi-rotors
So what then of manned multirotors, have they been left behind?
By no means, as the photo above
shows. German aircraft developer evolo has developed a manned multirotor that it calls a multi-copter. While
the company has previously demonstrated unmanned drones, on October
21st 2011 it accomplished what it
claims is a world first – a manned
electric multi-rotor flight.
It took place at an airstrip in southwest Germany and lasted one and
a half minutes. Thomas Senkel, a
physicist and designer/builder of the
multi-copter, piloted the aircraft from
a centre-mounted seat, using a handheld wireless control unit. The flight
consisted mainly of manoeuvering the
multi-copter around within a fairly
small area – no sense in getting cocky.
“The flight characteristics are good
natured,” Senkel said afterward.
“Without any steering input it would
just hover there on the spot.”
According to e-volo, its multi-copter
is simpler in construction and mechanics than a helicopter and safer - it
can reportedly land even with up to
four of its motors failed, and its propellers experience much less wear.
siliconchip.com.au
Onboard computers running custom
firmware control the rotational speed
of the propellers, dictating the attitude
(horizontal orientation to the ground),
altitude and direction of travel of the
aircraft. Once again potential flight
times are limited and range from 10
to 30 minutes, depending upon battery capacity and payload. As in most
aircraft, payload and endurance fight
with each other for supremacy with
the mission requirements deciding
the final outcome: long endurance,
small payload; high payload, short
endurance.
Lithium polymer batteries
There is an enormous amount of
technology and development that
has needed to come together to make
these tiny fully autonomous machines
possible. From the satellite-based
GPS system through micro-miniature
electronics to tiny electric motors and
batteries, all have played their part.
However, from a purely practical,
operational viewpoint the underlying
technology which has made the Nanoquads possible is the lightweight,
high energy density lithium polymer
battery.
These batteries have completely altered the miniature aircraft landscape.
For the first time, electric powered
model aircraft are successfully challenging the internal combustion (IC)
motor’s position of supremacy; at
least in the field of short endurance
flying operations. This is the “Achilles heel” of electric powered aircraft;
endurance!
Until battery manufacturers manage to produce batteries or power
sources with energy densities similar
to liquid fuels, electric powered flight
will remain the “country cousin” of
IC engines. That said, however, even
a twofold or better increase in battery
energy density will open up all sorts
of possibilities for electric powered
flight. That is how close the battle is
balanced. As an example, almost half
Modern RPAs have only become possible with the miniaturisation (and power)
of today’s computers. The computer makes all the adjustments necessary (to
motor speed especially) to actually keep the thing in the air!
of the models used in the recent World
Aerobatic championships, a typical
short endurance event, were powered
by electric motors.
The author, given equality in energy
densities, would use electric power
exclusively in his company’s RPAs
for a host of reasons including lack of
vibration, reliability, low noise and
ease of handling (starting and stopping the motor in flight, fuel cartage
and storage etc).
In short, in many areas electrics
leave ICs for dead but for long endurance RPAs at the moment electrics just
simply do not cut it.
Thus we see that from the outset
the electric powered quadcopter is
primarily a short range and short endurance vehicle thus ideal for line of
sight operations.
How does it work?
The quadcopter is quite different
from both helicopters and fixed wing
aircraft. With no fin, rudder, elevators,
ailerons, collective or cyclic pitch, just
how do these things work?
In the following explanation the
description will concentrate on a simple quadcopter on the understanding
that the same basic principles apply
to all multi-rotor craft. Basically they
consists of series of rotating propellers,
some rotating clockwise and some rotating counterclockwise. The reaction
between the thrust and torques generated by these propellers (or rotors) are
used to stabilise and manoeuvre the
machine as well as provide the lift
required for vertical ascent.
For hovering flight, the torques must
be in equilibrium and the thrust must
equal the weight. Any imbalance in
this equilibrium will result in a change
in attitude or altitude with a resulting
change in position.
As well as this the quad can be
configured in the “X” or “+” configuration, completely altering the control
Diagrams showing the effects of torque
and thrust. Diagram on the left shows
the effect increasing thrust on one motor
and reducing thrust on the
opposite motor. Diagram
right shows reducing
thrust on the opposite pair
results in a rotation around the
Z axis.
siliconchip.com.au
August 2012 21
It’s not all fun and games: this RPA (equipped with
camera) is relaying – in real time – close-up shots of
this 50m mobile phone/microwave relay tower to the
video operator on the ground
(inset below). This operation requires two
controllers – one “piloting” the plane with the
second controlling the camera direction, zoom
and focus while capturing the images required.
This system also has huge potential in the movie/TV
/advertising and commercial production area, too.
inputs required to stabilise or move
the aircraft.
The “+” configuration requires the
control of two motors at a time for a
change in horizontal position. If motor
one decreases RPM and motor two increases RPM then the quad will move
off in the direction of motor 1 (top of
the page) due to the vectored thrust.
Likewise left, right and backwards
movements are achieved with the appropriate thrust vectors.
On the other hand X configuration
requires less thrust on the two front
rotors and more thrust on the two rear
rotors to move forward. Both configurations then require Z-axis compensation to correct for the rotation induced
by these thrust (torque) changes.
The quad therefore must be controlled in the X, Y and Z axes for positional placement as well as controlled
to prevent rotation around these three
axis. The rotation around the X, Y and
Z axes roughly equates to the control
of an aircraft in the Pitch, Roll and
Yaw axes.
However, there is one very powerful
difference. Any rotation around the X
or Y axis will result in a thrust vector
which will move the quad left, right,
forward or backwards in the horizontal
plane. Any imbalance around the Z
22 Silicon Chip
axis will result in a rotation clockwise
or anti-clockwise around that axis.
Thus control of all four rotors simultaneously is required to maintain
the correct orientation of the quad in
relation to the nominated reference
point (eg, front of the quad).
For example, if a camera is mounted
on the front of the quad with a simple
Here’s the hi-res
image transmitted
from the RPA:
crystal clear, perfect
sharpness. Sure beats
climbing a ladder!
single axis horizontal-to-vertical camera mount, the camera can be swung
left or right by inducing a rotation
around the Z axis by a change in the
balance of torques.
Programming one of these little
devils is not for the faint-hearted but
fortunately most of the delicate control
inputs required to hold equilibrium
No, it’s not a computer simulation: it’s a swarm of tiny RPAs, flying indoors, in a
controlled formation with no risk of collision. . .
siliconchip.com.au
Fig.2: this diagram shows the
conditions for hovering flight.
with no rotation around the Z
axis. All motors are equal in
RPM with two rotating
clockwise and two anticlockwise and thrust
equal to weight (not
illustrated).
can now be taken care of automatically with modern inertial
management unit (IMU) sensors.
Fortunately, with modern sensors, all of the corrections
required can be programmed in as automatic responses.
The overall effect in a correctly set-up quad is for a very
stable camera platform, free of vibration and able to fly
forward, backwards, sideways, up or down and rotate
around its own axis.
Thus the requirement for a complex gimbaled camera
mount can be reduced to a simple single axis mount moving the camera from horizontal to vertical, resulting in a
great saving in weight and complexity.
We’ve focused on the small electric-powered quad-rotor
but these machines can be quite easily fitted with standard
IC engines and built to any size, as we have seen from the
early efforts undertaken in the 1920s although the thought
of starting and tuning four model-sized IC motors is quite
daunting.
Just what the future holds for multi-rotor machines
remains to be seen but you can rest assured . . . we ain’t
seen nuthin’ yet!
SC
A tiny video camera
can be fitted to all but
the smallest RPAs to relay images back to earth. It’s shown
here (left) mounted in the end of one of the radial arms. By
contrast, the large RPA shown above left was fitted with the
latest Canon EOS 650D digital camera, complete with 1855mm zoom lens, on a tilt and pan gimbal. All aircraft and
camera functions are controllable from the ground.
NEXT MONTH: We’ll look at another RPA, an electric
Piper Cub, fully kitted out for remote piloting and photography. We’ll also look at some “real world” flying situations.
siliconchip.com.au
RPA OPERATIONAL GUIDELINES
The instruction issued by the US congress to the FAA states
that RPAs under 55lb (25kg) are to be allowed into shared US
airspace by 2015 with small RPAs under 2kg, later upgraded to
11.3kg) operated by emergency services to be given permission
within 90 days.
This is expected to lead to an explosive growth in people and
companies queuing up for Company Operating certificates and
Remote Pilot Licenses (RPL).
In the US, the 90-day set of FAA rules will apply only to Police
and other first-responder RPAs smaller than 25 pounds (11.3kg)
that are flown in daylight below 400 feet, and that stay within
line-of-sight.
There are several police forces here in Australia investigating
RPAs and the multi-rotors are of great interest to the TV media. Of
special interest in this stampede towards RPAs is the quadcopter.
Here in Australia, the Author has been a part of the team
developing the CASA Level 1 RPL and it has been a very
interesting project indeed. The Level 1 license covers operations
carried out below 400 feet, visual line of sight (VLOS), Day Visual
Meteorological Conditions (VMC), 3nm from an aerodrome and
not over populous areas.
There is also talk of a weight limit of 55lb, certainly in the USA,
while in Australia at the moment that current limit is somewhat
higher. The aircraft that fits most easily into these regulations
and with the widest application is the small multi-rotor and thus
the majority of people lining up to be issued for the RPL Level 1
are multi-rotor operators.
For the hobbyist SGMA (self-guided modeal aircraft) operator,
the Model Aeronautical Association of Australia (MAAA) has
proposed a set of guidelines (MOP067) for what they term
SGMA. Briefly, these guidelines propose a weight limit of 5kg
with motor size limits (Electric and IC) and operations carried
out below 400 feet, VLOS, Day Visual Meteorological Conditions
(VMC), and on MAAA approved flying fields. For the complete
MAAA policy follow this link: www.maaa.asn.au/maaa/mop/
policy/MOP067%20-%20Policy%20SGMA
It is interesting to note here the MAAA definition of line-ofsight. The MAAA specifies that the pilot must be able to tell the
model orientation at all times, should he be forced to resume
manual control as below.
MAAA SGMA VLOS Definition: the maximum range at which
the Pilot in Command can clearly determine the orientation and
also manually control the Model Aircraft in sustained flight. CASA
CAR (1998) Part 101 states that “a person may operate a model
aircraft only if the visibility at the time is good enough for the
person operating the model to be able to see it continuously”
(101.385).
For those interested in the differences between SGMAs and
RPAs from CASA’s perspective, this link tells the story: http://
casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_100375
Of particular importance for all RPAs and SGMAs is a return to
launch (RTL) feature which is initiated automatically upon loss of
the data link or manual control.
Also the autopilot should automatically return the aircraft
to launch should the RPA or SGMA exceed an operator predetermined distance from home (eg, the pre-determined MAAA
defined VLOS distance for that particular model).
All small commercial autopilots also have an added legislated,
anti-terrorist feature built-in, that being a RTL if 300km distance
from home is exceeded.
August 2012 23
NICHOLAS VINEN
gets to play!
Parrot AR Drone 2
QuadCopter
This impressive flying beast sports four rotors and two cameras. You
can control it with an iPhone, iPad or Android device and capture 720p
video of its exploits. It’s quite robust, easy to fly and has multiple control
modes to suit different pilot experience levels.
T
here are plenty of build-ityourself kits out there now for
quadcopters – but building your
own isn’t for everyone.
For those who want to have the fun
without doing much work, the AR
Drone 2 comes fully pre-assembled
and it has many impressive features.
Chief among these is the high definition wide-angle video camera with live
streaming as well as recording to a USB
flash drive.
The main part of the drone houses
the electronics and battery. Four carbon
fibre tubular arms project from this with
the rotors, motor drivers and motors at
the end of each.
You then slip one of the two expanded polypropylene “hulls” over
the body, which protects it from damage in the event of a minor accident or
collision.
The “outdoor hull” only covers the
electronics and battery, leaving the rotors exposed. This gives the best flying
performance because it’s quite light. It
24 Silicon Chip
also means that if you fly too low, you
might end up mowing the lawn!
The “indoor hull” is larger and surrounds the rotors entirely as well as
providing more protection to the main
body. This reduces the chance of major
damage in the event you strike a wall
or some furniture.
We found the AR Drone 2 to be pretty
robust, especially with the indoor hull
in place. With it, it can shrug off minor
impacts with obstacles; if you don’t hit
them too hard, you can continue flying,
often without any damage.
This is of course great for beginners,
who will probably have a few mishaps
before they get the hang of controlling
the Drone.
It also has an an automatic motor cutout if the unit experiences an impact,
tilts past a certain angle or detects the
rotors hitting an object. The unit will
normally survive the resulting fall
without any serious damage as long
as it isn’t too high and/or the ground
below it is reasonably soft (eg, grass).
We had this feature activate a few times
with our demo unit and each time, it
was still perfectly flight-worthy.
This is thanks to its sturdy construction and energy-absorbing arm mounts;
one arm usually takes the brunt of any
impact.
The hull, being made of a foam material, is the most likely part to break
but if does split, it can simply be glued
back together. They even give you some
double-sided tape in the box for field
repairs, should they be necessary.
Stability and control
The AR Drone 2 is self-stabilising.
When you press the take-off button, it
rises straight up from the ground to a
height of about one metre and hovers
in place until you are ready to take
control.
At any point, if you take your hands
off the controls, it returns to a stable
hover – this is great for beginners since
if you lose control this is an easy way
to recover. And if it’s being blown away
siliconchip.com.au
Here’s the more “decorative” version of the Parrot intended for outdoors flying where there’s less risk of damage to walls,
furniture, etc. It also has better performance than the “indoor” version with its polypropylene “hull”. The colourful
carapace also has an important outdoor benefit: it allows you to work out the PRA’s orientation at a distance.
by wind or something like that, you can
just press the “land” button and it will
gracefully settle down onto the ground.
If it flies out of range, it will hover
and wait for you to get closer. The stated
range is 50m in an open space but we
were able to control the demo unit out
to a range of about 100m.
If the Drone’s battery runs out during flight, it lands itself but you get a
warning beforehand so you can fly it
to a safe location for landing. If you’re
controlling it with a phone and somebody calls you, it will either hover or
land, depending on whether you’ve set
it to indoor or outdoor mode.
There is a LED in each corner of the
Drone, underneath the rotors. In flight,
the two at the front turn green while the
others are red, so you can see which
way it is facing.
Sometimes they can be obscured by
other parts of the Drone and so it isn’t
always clear which way the Drone is
facing just by looking at it.
If we owned one of these, we would
think about fitting a bright blue LED
under the camera to give a clear indication of which way it’s facing or perhaps
paint the front a bright colour.
With the outdoor hull in place, the
front is a bit more obvious since it looks
significantly less symmetrical than the
indoor hull.
siliconchip.com.au
Performance
We found the AR Drone 2 to be fairly
agile. It certainly can spin fast and it
can move in any direction parallel to
the ground at up to about 18km/h.
Its speed and manoeuvrability are
impressive but having said that, we
have seen some home-built quadcopters which are significantly more
agile; this is mainly due to the fact
that the AR Drone 2 uses surprisingly
small 14.5W brushless motors while
home-built drones tend to use more
powerful units.
Beginners and recreational flyers
should be satisfied with the performance. People who really enjoy flying
the AR Drone 2 may then decide to
build their own and use larger motors,
to get real acrobatic performance.
Absolute and relative modes
You have two main choices of control
mode, called “relative” and “absolute”.
Absolute control is rather clever and it’s
what we prefer to use if you are flying
the drone by looking at it, which is
easier when flying indoors. In fact this
is by far the easiest mode for beginners.
When you enable absolute mode,
the software takes advantage of a magnetometer (ie, 3-axis compass) in both
the AR Drone 2 and your phone/tablet
to work our how they are orientated
relative to each other.
Then if you tip the phone/tablet to
your left (or in joypad mode, move your
left-hand thumb to the left), the drone
will move to your left, regardless of
which way the drone itself is facing.
In this mode, you don’t need to yaw
the Drone at all, except if you want
to aim the forward-facing camera in a
particular direction.
By comparison, in relative mode, the
controls act depending on the direction
the Drone is facing. This is the mode
you need to control the Drone if you
are looking at the camera feed, since
your are then looking at whatever the
Drone is facing. You can also use this
mode without using the camera but
this takes more concentration than
absolute mode.
If you’re going to be flying the drone
out of direct line-of-sight then you will
need to fly using the camera and hence
will be using relative mode.
Note that the camera update rate
depends somewhat on the speed of the
processor in your control device; we
found it much easier to fly using the
camera on a fast Android tablet than
we did with an iPhone, where the video
update rate was rather sluggish.
Controls
Once you have chosen absolute or
August 2012 25
The Parrot can be
controlled via an
iPhone (as here), iPad
or Android phone/
tablet (although we
had problems with
some Android tablets).
Essentially the Parrot
becomes a WiFi access
point – the pic on
screen is what the
Parrot sees via its onboard camera!
relative mode, you have some additional options.
In “joypad” mode, the four main
degrees of freedom are controlled with
your thumbs placed on either side of
the smart-phone or tablet screen, as if
it’s a game controller. In this mode, your
left thumb controls movement parallel
to the ground, ie, moving forward and
backward and “slipping” left and right.
Your right thumb controls altitude (up/
down) and rotation left and right (ie,
yawing). This can be swapped if you
are left-handed.
In the alternative mode, the right
thumb control is identical but forward/
back/left/right movement is controlled
by tipping the phone or tablet. The
software detects the tipping using its
built-in accelerometer.
This is probably the easiest mode for
beginners. But it’s impractical if you
are going to be using the video feed to
fly the Drone since you can’t really see
the video while you are busy tipping
the controller.
This combination, where one hand
controls altitude and yaw and the other
movement in the horizontal plane is
similar to what is commonly known as
“mode two” for helicopter control. But
we tend to prefer “mode one”, where
one hand controls yaw and forward/
back movement and the other controls
altitude and left/right movement. Unfortunately, the software does not seem
to offer the ability to switch between
these modes. This is a pity as it would
not be difficult to do and many people
will prefer mode one, which is commonly used in Australia.
Our other main complaint about
the controls is that since the control
“sticks” are virtual, you don’t get any
tactile feedback from them. With real
“joystick” type controls, the centring
springs let you know how far you have
moved the stick from its neutral position without having to look at it. This
is not the case when you are simply
26 Silicon Chip
pressing your thumbs on the screen of
a smart phone and so it’s easy to lose
track of the control positions.
It’s also quite easy to accidentally
move your thumbs outside the control
zones, in which case the phone will
beep to let you know you’re not longer
controlling the drone. This is why we
tend to prefer using a proper remote
control transmitter for this sort of job
but then you would need a separate
device to view the video feed from
the Drone.
When configuring the controls for
the AR Drone 2, you can set various
parameters which limit the rate at
which it moves, turns, how high it will
fly and so on. The initial settings are
quite low and presumably are intended
for beginners, so they won’t crash it too
hard if they lose control.
However we found it a bit easier to
fly the Drone with the limits turned
up as it’s then possible to make faster
corrections to its flight path.
The AR Drone 2 also has a “flip”
mode where it does a somersault,
which can be used when hovering or
during flight. It seems to be primarily
useful for showing off!
This is activated by double-tapping
the left control “stick” but can be disabled to prevent accidental activation
if it isn’t being used. An accidental
flip at low altitude could cause quite
a nasty crash.
Technology
The electronics behind the AR Drone
2 are impressive. The main controller
module is powered by a 1GHz ARM
Cortex A8 32-bit processor with an
800MHz video DSP and 128Mbytes
of memory. This runs Linux and has a
Wi-Fi interface. It is effectively a flying
Wi-Fi access point!
To control the AR Drone 2, you first
have to join its network. It is over this
network that both control signals and
video are sent.
Each rotor is driven by a separate
brushless motor which, as mentioned
earlier, produces up to 14.5W and is
about the size of half of a AA cell. The
motors are mounted on PCBs, each
with an 8-bit Atmel microcontroller
which drives the windings in sequence,
controlling speed. These are in turn
controlled by the main board over a
serial bus.
For position and speed feedback,
the controller effectively has what is
known as a nine degree-of-freedom
(“9DOF”) sensor comprising 3-axis
MEMS accelerometer, 3-axis MEMS
gyroscope and 3-axis magnetometer.
This allows it to measure instantaneous acceleration, change in rotation and
orientation and it is this information
which allows it to automatically hold
its position in a hover.
The stabilisation system can compensate for wind and other factors
although note that it could be overwhelmed by strong wind gusts. The
stabilising system also becomes less
effective once the drone is more than
six metres or so above ground level
although we found it was still pretty
good.
For more information on how the
controller is able to stabilise and move
the quadcopter through the air, see the
accompanying feature article in this
issue (page 21).
For measuring height, the AR Drone
2 sports both a pair of ultrasonic sensors
on the underside as well as a pressure
sensor for measuring altitude (with
<1m resolution). It can measure its
altitude at take-off and compare it to
the present altitude to implement its
adjustable height limit (“ceiling”). At
lower levels, the ultrasonic sensors give
it more accurate feedback.
The video quality from the main
camera is good; the fast DSP allows it
to do high-quality video compression
in real time, which is necessary in
order to get the video over the limited
bandwidth of the wireless link.
It also has a downward-facing camera
(320x240 pixels) which can be used to
check whether it’s safe to land the unit
if you can’t see what’s immediately
below it from your vantage point. A
button on the screen switches the view
between the two cameras.
As well as allowing you to see what’s
under the drone, the downward-facing
camera is also used to estimate ground
speed (in conjunction with the height
measurement). This then lets you limit
siliconchip.com.au
The four motors are tiny –
this shot from underneath
shows one of the motors
(circled) mounted on the
arm which also houses
the landing “foot”, along
with the motor control
electronics. You can see
the massive gearing down
of the motor from the size
of the propellor shaft gear
versus the just-visible
motor shaft gear.
the Drone’s horizontal speed.
You can similarly limit its maximum
angle of tilt (measured with the accelerometer) and rotation speed (via gyros).
That’s a lot of different things to adjust.
In fact there are several screens full of
settings you can play with.
Build quality
We weren’t just impressed with the
electronics in the Drone. Some clever
mechanical and material engineering
has also gone into the design.
The rigid parts are, well, rigid while
other parts are designed to have some
“give” to reduce vibration and absorb
impacts. For example, the battery is
suspended on a flexible bed in order
to prevent its weight from affecting
stability. The motor, arm and rotor assemblies are designed and made with
precision. Even the foam hulls are accurately moulded.
One common problem with cameraequipped drones is image blurring due
to vibration from the motors and rotors.
We didn’t see any evidence of this from
the AR Drone 2 and according to Parrot, this is due to carefully designed
flexible joints between the arms and
main body which prevent vibrations
from being transmitted to the camera.
It seems to work well.
Software
We found the software easy to install
and set-up on an iPhone and we expect
it will be just as easy on an iPad. We
didn’t run into any problems with the
iPhone software; it’s responsive, logical
and easy to use. Ideally you would use
a tablet since the iPhone screen is a little small to view the video, especially
with controls and read-outs partially
obscuring it. The iPhone also gave a
slow video update rate.
The Free Flight software is also
siliconchip.com.au
available for Android and is virtually
identical to the iPhone/iPad application. It requires Android version 2.2
or later as well as a multi-touch screen
and accelerometer.
We expect most Android devices
would meet these requirements but
surprisingly, of the four we tried, it
would only install on one.
The version requirement is a bit of
a problem since even some fairly new
Android phones are only running on
version 2.1; the Publisher has one and
it’s only just over a year old. Two others we tried were running version 4.3
and appeared to meet the requirements
but the software refused to install, in
each case saying the device was not
supported.
On an Asus Transformer (Android),
the software worked quite well with
the exception that a couple of times we
got stuck in piloting mode and had to
“kill” the application to get out of it.
It could have been worse; at least
if you’re stuck in piloting mode, you
retain control of the drone. The video
quality and update rate were very good
on the Transformer.
If you have an Android phone or tablet and are interested in the AR Drone
2, your best strategy is to install the
software first and check that it works
before you buy the hardware. To do
this, just follow the link to the free software from the Parrot website at http://
ardrone.parrot.com/parrot-ar-drone/
Hopefully, the compatibility problems and software glitches will be
sorted out with a software update.
Oh, and Parrot also provide firmware
updates for the Drone itself, should this
be necessary.
Battery
The AR Drone 2 comes with a 3-cell,
1Ah Lithium Polymer battery which
is good for about 12 minutes of flight.
The software has a battery meter in the
corner of the screen so you can keep
track of the charge state while flying.
This battery clips into a plugpack-style
balance charger and it charges reasonably quickly – up to about 90 minutes,
but usually less than an hour unless
you’ve run it right down.
That’s pretty good but if you want
to take the Drone out to a park for an
extended flying session you will probably want to buy some spare batteries.
Parrot insist that you only use their
batteries but a little birdie told us that
you can use other 3-cell Lithium Ion/
Polymer batteries if you make a suitable
adaptor cable.
Spare parts
Most of the AR Drone parts are available as spares so that you can repair it
if you have a prang. Having said that,
careful pilots should not need to be replacing parts very often given its overall
robustness. Mostly minor impacts just
result in some scratches or maybe split
the hull; as beginners we had a number
of “oops” moments with our demo unit
but only did relatively minor damage
to the hull.
Inevitably most owners will eventually end up breaking something that
you can’t fix with tape. When you do,
you can get replacements for most of the
parts from their website (URL below).
They also sell a range of accessories to
customise your Drone or play games
with it.
Conclusion
The AR Drone 2 itself is an impressive piece of gear, well-built and cleverly designed with a lot of excellent
features.
The story with the software is not
quite as rosy although if you manage to
get it installed, you shouldn’t run into
many issues. We hope and expect that
the Android application will receive
some improvements in the near future.
If you’re looking for a well-made
pre-built drone that’s fun to fly and
with lots of features, the AR Drone 2
is hard to beat.
Price & availability
The AR Drone 2 retails for $349 and
is available for purchase at their website: http://ardrone.parrotshopping.
com/au/p=ardrone=main.aspx
It is also available from many elecSC
tronics and hobby retailers.
August 2012 27
RPAs in Action:
By Ross Tester
Designing, building and
using RPAs for business
SILICON CHIP talks to (while we watch in awe!) two young men who
are dedicated RPA hobbyists turned businessmen: they are setting up
a company specialising in aerial cinematography for movies and TV
using RPAs – one of the first in Australia to do so.
O
n page 22 we showed an RPA – in this case a large
octocopter – taking photographs at the top of a
50m-high communications tower and relaying the
images back to ground operators in real time.
That particular octocopter – a huge thing compared to
the Parrot we reviewed – is one of several belonging to
Matt Chang and Peter Maruncic. They’ve formed a business
called “Rotorworks” to use RPAs in film, TV and advertising production, giving producers and directors hitherto
impossible-to-obtain aerial shots and angles, at dramatically
lower cost than traditional methods.
“Previously only a real helicopter could get the angles
but could never approach to such intimate close-up distance that we can achieve with our octocopter,” said Matt.
With 35+ years of RC aircraft experience, Matt is the Chief
UAV controller who will be certified to fly the octocopter,
while Peter with 25 years RC experience is the Aerial Video
operator and UAV controller.
Matt was one the first UAV Operators certified back in
year 2000 with the pioneering use of RC blimps for aerial
advertising.
With multi-rotor technology now available and certifi28 Silicon Chip
cation to operate commercially in Australia, they are in a
unique position to shoot aerial angles that have never before
been available to the cinematographer without significant
investment in manpower and costs.
“We can fly indoors or outdoors and we can get her
moving up to about 60km/h or faster if required for high
speed tracking shots.”
“Importantly, we can shoot in high-risk locations in
complete safety and zero risk to people, with almost zero
set-up time. For example, it’s simple for us to hover off a
cliff face, above a tree or under a bridge. We can also take
off and land on a moving boat. Shots over water are another
great aspect of what we can offer, even take off and landing
on water if required.”
Aircraft
Matt and Pete currently have about seven multi rotor
aircraft of all types that carry all types of cameras, from a
tiny GoPro to large Epic.
The smallest craft can fly through narrow doorways and
windows if required, while still carrying a camera (albeit
a small one)!
siliconchip.com.au
Invasion of the RPAs! While the smallest of these are virtually hobby machines, they are still capable of taking a small
camera aloft. But the real work is done by the hexacopter (at rear) and the octocopter at front. The orange-coloured radial
arms assist the operator in orienting the craft from a distance – they’re mounted facing forward (same direction as camera).
The Octocopter
Of most interest to us was their giant octocopter, an
eight-rotor electric-power RPA developed specifically for
cinematography.
It uses very powerful brushless motors and is quiet compared to past technologies. An onboard computer stabilises
the craft while movement is controlled from the ground.
The octocopter can fly for 10-15 minutes at a time,
depending on the manoeuvres required. Batteries can be
swapped for near-continual flying if needed. Battery swap
time is approximately three minutes.
Onboard is a GPS which allows Matt to do a number of
things to aid in filming:
• GPS position hold: locks at any altitude and position
above the earth.
• GPS return home: with the press of a button, the octocopter will return home and land automatically; this is
a great feature for safety.
• GPS Circle waypoint: it can circle a point chosen
anywhere on earth, all while the camera is pointing in
towards a subject.
• Follow Me: The octocopter can follow the controller
automatically as they walk or drive at a speed of between
three and ten metres per second.
• Point-and-click-to-fly is also possible from a ground station. One click with the mouse on a Google map and the
octocopter flies there.
uses on the ground.
If required, it can relay HD video to the ground but there
is a weight penalty, which reduces endurance.
Safety
In terms of safety and insurance, they offer $10-$20 million Professional Indemnity Insurance from an Aircraft
Insurance company.
Flying is limited to dry conditions and wind less than
20 knots, with a height restriction of 400 feet,
This could be a great opportunity for customers as they
are one of the first companies that will be able to do this
legally in Australia, as officially certified by CASA.
Currently in the US there is no provision for any form
of licence to use these aircraft so we feel very lucky that
Australian laws permit this type of operation.
Contact:
Rotorworks (Matt Chang & Peter Maruncic)
Phone: 0405 902 033
Website: www.rotorworks.com.au
‑
Cinematography
In terms of cameras, the respective aircraft can carry
anything from a GoPro, which weighs a couple of hundred
grams, to a Red Epic which weighs 2kg plus lens.
An even bigger machine could be built if a client wanted
the craft to carry two Epics for 3D work.
The camera gimbal uses high speed servos to level
the camera platform and can control its roll, tilt and pan.
There’s also an onboard computer that takes care of camera
stabilisation which updates 800 times per second to provide
rock-solid stabilisation. Continuous and unobstructed 360°
filming is possible.
Recording is done on-camera but there is also a live fullvideo pass-through transmission that the camera operator
siliconchip.com.au
Hover mode: the hexacopter remains completely still while
the operator’s hands are off the controls. This aircraft has
provision for a camera though none is fitted.
August 2012 29
Matt and Peter tell us about their aircraft and systems. . .
The small Quadcopter airframe we flew is called a Kinjal and
is made from carbon plate and computer motherboard standoffs.
The brains behind the act is what we call a Flight Controller or
FC. The particular one demonstrated doing aerobatics is called
Quadrino and is one of the many flavours of “MultiWii” based
flight controllers currently available.
The Wii in MultiWii stems from the original use of the gyro and
accelerometer in the Nintendo Wii Motion Plus and Nunchucks.
Those gyro and accelerometer boards are stripped out and hooked
up to Arduino boards. MultiWii is one of many open source flight
controller software projects and is based on the Arduino platform.
Originally started in 2010 by RCGroups user “AlexinParis” the
software development has a huge following and the RCGroups
MultiWii thread currently runs at 27,500 posts.
The Multiwii software supports a 3-axis accelerometer, 3 axis
gyro, 3-axis magnetometer, barometer and a GPS. Various forks of
the software support other extras such as LED lights and ultrasonic
sensors. You can learn more about it here:
www.rcgroups.com/forums/showthread.php?t=1261382
A large index of multi-copters and software developments
can be found here: www.rcgroups.com/forums/showthread.
php?t=1097355
In the world of ready-to-fly flight controllers there are a few
that seem to have had commercial success: MikroKopter (MK),
Hoverfly, DJI Innovations and the newcomer, ZeroUAV.
MK is developed by Holger Buss who was one of the first to
develop an affordable commercial solution good enough for aerial
photography and video.
We fly with a DJI Flight controller called Wookong which is
easy to set up and flies well out of the box. It’s also expandable
from the default GPS and attitude hold, through to multi-waypoint
navigation systems with a ground station.
All of the features are locked up onboard and after an on-line
payment, DJI unlocks the extra features with a special serial code.
The Newcomer ZeroUAV has really given DJI a run for its money
as it is developed by an ex-employee of DJI. The ZeroUAV YS-X6
has some great features such as WiFi telemetry downlink to your
iPhone or Android device; FollowMe allows the multi-copter to
literally follow you by tracking your iPhone’s position and circle
mode which circles a point on earth while pointing the camera at
the centre point. With the introduction of these great features, DJI
seems to have become more competitive and will introduce some
exciting new features soon. It’s a good time to be in this hobby
with such rapid development in all areas of the hobby.
The DJI and ZeroUAV solutions have some very tricky ways of
insulating the onboard circuitry from the airframe’s vibration by
mounting the gyros and accelerometers onto a small metal and
lead covered block.
The take-apart guides are here: Wookong technical review –
www.rcgroups.com/forums/showthread.php?t=1510587
ZeroUAV technical review – http://www.rcgroups.com/forums/
showthread.php?t=1676150
Our Wookong powered octocopter uses eight brushless motors
powered by eight 40A ESCs (Electronic Speed Controllers). Thrust
generated with our setup peaks at just over 10kg.
The Motors run at 770 RPM per volt which equates to a realworld RPM of about 7500 when hovering. Our starting voltage
is about 16.8V on a fully charged (4 cell) LiPo (lithium polymer)
battery and we land when it’s about 13.2V. Any lower than that
starts to deteriorate the batteries permanently. Our endurance with
30 Silicon Chip
The small Kinjal
quadcopter is capable
of unbelievable
aerobatics.
16Ah of battery capacity is about 12 minutes.
The frame, made of carbon plate, was developed in-house and
cut on a DIY 3-Axis CNC milling machine. The booms that secure
the motors are aluminium and carbon fibre.
We use very light weight carbon fibre propellers which can
react quickly to keep the multi-copter balanced, as instructed by
the flight controller.
With all that payload potential we can lift a gyro-stabilised camera platform or gimbal. Our gimbal is made by Photohigher of NZ
who have developed an amazing system to stabilise the camera
platform. The controller board is attached to the camera tray and
uses its accelerometers and gyros to maintain a level camera
platform at a rate of 800Hz. When tuned, camera stabilisation is
near instantaneous.
There are only a few certified UAV operators in Australia who
are legally permitted by CASA to operate commercially and shortly
we will have earned our Operator’s Certificate too.
It’s worth noting the amazing change in RC Hobbies with the
recent growth of the famous Chinese based powerhouse of hobbies “Hobbyking.com”. Their RC products are all sourced direct
from the manufacturers so have dramatically reduced in prices,
and entry into the hobby is more affordable than ever before. For
example, where batteries like we now use used to cost upwards
SC
of $150 each, they now cost in the realm of $15 to $40.
The octocopter is made of
lightweight materials but with
batteries, camera and all the
control gear it’s still a handful!
siliconchip.com.au
CIRCUIT NOTEBOOK
Interesting circuit ideas which we have checked but not built and tested. Contributions will be
paid for at standard rates. All submissions should include full name, address & phone number.
S1
7
4
PICAXE
ICSP
SOCKET
22k
10k
P3
2 SER
IN
D1
1N4004
220nF
1
Vdd
P0
47
560k
330
P1
Vss
8
A
A
LED1
LED2
(IR)
C
K
E
B
Q3
(IR NPN)
C
E
Q2
BC338
B
C
E
Q1
BC338
BC338
LED1
1N4004
A
siliconchip.com.au
–
4.5V
BATTERY
MOUSE BREAKS
BEAM
This mouse trap uses an IR LED
and phototransistor coupled with
a PICAXE08M microcontroller to
operate a small motor that closes
a trap door. This design avoids the
main problems with traditional
spring-based traps, in that they are
difficult to set and often fingers are
caught during setting up. Secondly,
the sneaky mice often eat the bait
without setting off the trap.
This humane trap is constructed
from two short lengths of 25mm
PVC pipe, with a right angle elbow
in the middle and a snug-fit removable cap at one end. The bait (usually chocolate) is placed at the cap
end. About one centimetre from the
other end of the pipe assembly is a
slot for the trap door that is cut half
way through the pipe.
The trap door is cut out of some
sheet metal to fit the internal curve
of the pipe and arranged so that it
can pivot into the pipe and seal the
exit. A 2mm diameter hole in the
door and a pin in the shape of a
threaded eyelet is inserted to keep
it open. The pin is connected to the
shaft of the motor via a short cord.
When the trap is triggered, the
motor is energised for a short time,
A
MOTOR (4.5V)
TO RELEASE
TRAPDOOR
1k
5
K
PICAXE-based mouse
trap is non-lethal
+
1k
IC1
3
PICAXE P4
-08M
P2
8
SPEAKER
330
6
K
K
K
A
B
E
C
wrapping the cord around
REMOVABLE
the shaft and pulling the
END CAP
trap door pin out to reFOOD BAIT
lease the door, with gravINSIDE PIPE
ity closing it.
The mouse detection
IR PHOTO TRANSISTOR
Q3 OVER UPPER HOLE
circuit is located at the
IN PIPE, IR LED2
bait end of the trap and
UNDER LOWER HOLE
WEIGHT TO
comprises an IR LED
ENSURE TRAPDOOR
opposite an IR phototranFALLS WHEN RELEASE
sistor. When the mouse
PIN IS PULLED OUT
breaks the beam, the trap
MOTOR
door is closed.
CORD ATTACHED TO
The IR LED and photoTRAPDOOR RELEASE PIN
TRAPDOOR
transistor were sourced
from an old disk drive.
Similar photo-interrupter
OPEN
components can be found
END OF
PIPE
in printers and can be
separated easily to be
HINGE BRACKET
placed apart so that the
FOR TRAPDOOR
mouse can interrupt the
IR beam.
The captured mouse is not harmed
At power on, a short tune is played
and can be released by removing the
and a red LED is flashed. After this
snug fit end cap. The trap could be
sequence, the red LED flashes to
adapted for other animals by suitindicate normal operation. The IR
ably scaling up of the pipe and other
LED is also pulsed briefly at the same
components. Power comes from
time, to prolong battery life. When
three 1.5V alkaline AA batteries.
the IR beam is broken, the motor
The software, MoustrapV4.bas,
is energised for a short duration to
is available for download from the
close the trap and the tune “Silent
SILICON CHIP website.
Night” is played to notify successful
Phillip Webb,
operation. The tune is repeated at 15
Hope Valley, SA. ($60)
minute intervals.
August 2012 31
Circuit Notebook – Continued
7-day programmable alarm clock
with 230VAC switching
The motivation for this project
came from a desire to have a clock
radio alarm in which each day’s
alarm can be individually set. Clock
radios are not available with this
facility so this design is the result. It
uses a PICAXE18M2 microcontroller
to perform the clock and switching
functions. S2 is the Mode switch and
its Run position is for normal clock
operation while the Minutes, Hours
or Days positions are used to set the
clock or alarm, depending on the
setting of Function switch S1.
The PICAXE drives a 16-character
2-line LCD (Jaycar QP-5516). The
top row shows day and time (AM/
PM format) and a flashing heart-beat
symbol (Ω) when in clock mode. The
bottom row displays the day and the
alarm-on time and alarm-off time in
24-hour format for that day, as well
as an asterisk symbol (*) indicating whether the alarm is set or not.
Switch S3 sets the alarm ON or OFF.
S4 is a DPDT momentary switch
with centre-off (Jaycar ST-0358). In
the Set position, the parameter selected by S1 and S2 is incremented;
the switch being returned to the centre position when the desired value
is reached.
When all the alarm information
has been set, S4 is momentarily put
into the STORE position, whereby
an interrupt routine in the software
stores the alarm information for that
day. The LED also turns on as a visible
confirmation. The alarm information
is stored in non-volatile memory so
it isn’t lost if power is disconnected.
The PICAXE18M2 has a TIME
variable which increments every
second. This could have been used
as the basis for the clock operation
but because of systematic error in the
internal oscillator, such a clock will
gradually drift out of time and will
need to be reset periodically. For this
reason, the timing circuit is based on
the 50Hz mains supply.
Positive-going 50Hz pulses are
delivered via diode D2 to the clock
input, pin 10, of IC2, a 4020 CMOS
14-stage counter. This is teamed with
gates IC3 & IC4 to produce one pulse
every minute from pin 4 of IC4b.
These pulses are applied to the reset
pin of IC2 (pin 11), which resets the
counter and it starts again.
The reset pin is also connected to
the B1 output of IC1. This is to allow
the software to reset IC2 after the time
has been set and the Mode switch is
returned to the RUN position. This
ensures accurate time-setting by
forcing the first minute to be the full
count of 3000 pulses.
The narrow pulses at pin 4 are
stretched to about 7s by IC4d and
IC4c to ensure that IC1 has ample
time to detect them. The detection
of the timing pulses at pin 10 is carried out using a parallel processing
routine which ensures that no pulses
are missed due to the processor being
busy doing other tasks.
The power supply is straightfor-
Jack H
is this m olliday
of a $15 onth’s winner
0 gift vo
ucher fr
Hare &
Forbes om
ward but the
7805 regulator
will need a heatsink if an LCD panel
with a backlight is used.
The alarm function can be manually switched on or off using switch
S3. If it is in the Auto position, the
programmed alarm times are executed. If the DAYS are cycled through
with the Alarm switch in the Off or
On position, the display will show
the alarm settings stored in memory
for each day. This allows the current
alarm settings to be viewed.
On the other hand, if the DAYS
are cycled through with the Alarm
switch in the Auto position, when
each new day is selected, the Alarm
setting for the previous day is displayed. This facilitates alarm setting
as it is often the case that one day’s
setting is also required for the next
(eg, Monday to Friday might all be
the same).
Finally, if the alarm for a certain
day needs to be cancelled, just increment the Alarm On hours for that day.
After cycling through the hours up to
23, the next increment will display
“no alarm”. Just use the Store switch
to store this condition and the alarm
will not operate for that day.
If the alarm needs setting on a day
showing “no alarm” just use the Set
switch on any alarm setting selection
and the display will revert to a zero
display for all alarm values which
can then be incremented and stored
in the usual way.
The software, ClockLCD1.bas,
is available for download from the
SILICON CHIP website.
Jack Holliday,
Nathan, Qld.
Your Reliable Partner in the Electronics Lab
ab
LPKF ProtoMat E33 – small, accurate, affordable
Hardly larger than a DIN A3 sheet: The budget choice for milling, drilling and
depaneling of PCBs or engraving of front panels – in LPKF quality.
www.lpkf.com/prototyping
Embedded Logic Solutions Pty. Ltd. Ph. +61 (2) 9687 1880
32 Silicon Chip
Email. sales<at>emlogic.com.au
siliconchip.com.au
3
1
2
ALRM
OFF
TIME
D4
1N4148
100k
K
A
S1
MINS
11
10
MR
CP
10k
FUNCTION
PICAXE ICSP SKT
4.7k
ALRM
ON TIME
4.7k
CLK TIME
4.7k
4.7k
4.7k
O4
O6
O5
O12
O13
7
5
6
4
2
3
LED1
100nF
8
Vss
O0
O11
O9
O8
O10
14
12
15
9
1
K
A
S4
ON
AUTO
470
22k
16
Vdd
RUN
S2
MODE
O3
IC2
4020B O7 13
DAYS
ON
HOURS
OFF
4.7k
STORE
OFF
SET
4.7k
100k
3
2
4
1
18
17
16
8
100nF
7
5
2 IC3a
1
4
6
B4
B5
B6
B7
B3
B2
IC4b
7
4
K
A
12
13
IC4: 4001B
100nF
B1
B0
6
15
10
11
12
13
9
8
100nF
IN6/C6
D3
1N4148
5
6
0V
5
C4/SER.IN
C3/SER.OUT
C5/RESET
PICAXE
18M2
+V
14
C2/IN2 IC1
C1/IN1
C0/IN0
C7/IN7
IC3: 74LS20
13
14
12
10 IC3b
9
S3a
ALARM
+5V
IC4d
14
11
10M
1 F
16 x 2
LCD MODULE
2
Vdd
2
1
9
8
7
IC4a
IC4c
3
10
22k
IN
R/W
5
CONTRAST
D7 D6 D5 D4 D3 D2 D1 D0 GND
1
14 13 12 11 10 9 8 7
EN
RS
+5V
6
4
4.7nF
100 F
GND
OUT
REG1 7805
A
K
A
LED
K
VR1
10k
ZD1
4.7V
1N4148
10k
10k
10k
3
K
A
1000 F
+12V
ON
OFF
AUTO
B
+
E
A
B
A
C
BC548
K
1N4004
S3b
Q2
BC548
E
C
D1
1N4004
PIEZO
BUZZER
S5
BUZZER
ON/OFF
K
B
A
K
IN
A
Q1
BC548
K
OUT
7805
ZD1
RELAY 1
230V
GND
E
C
T1
+12V
9V
D2 1N4148
A
10k
A
K
K
K
A
A
K
BR1
4x 1N4004
GND
A
N
E
E
N
A
AC MAINS INPUT
AC MAINS OUTPUT
siliconchip.com.au
August 2012 33
Circuit Notebook – Continued
DB9-M
DB9-F
1
1
6
7
8
9
2
2
3
3
4
4
3-WIRE CABLE
UP TO
16m LONG
6
CROSSOVER/NO CROSSOVER
7
S1
DB25-M
DB25-F
1
1
15 3
3 15
16 4
4 16
17 5
5 17
18 6
6 18
19 7
7 19
20 8
21 9
22 10
10 22
3
4
4
K
K
LED1
LED2
A
A
LEDS
7
8
9
5
5
DB25-M
DB25-F
1
1
14 2
2 14
15 3
3 15
16 4
4 16
5 17
6 18
19 7
7 19
8 20
20 8
8 20
9 21
21 9
9 21
22 10
10 22
23 11
11 23
24 12
12 24
25 13
13 25
11 23
12 24
25 13
13 25
4.7k
Serial cable for
old computers
This cable adapter was developed
from a need to send files to and from
a PC to various vintage computers
and to avoid the frustration of having
4.7k
K
A
to have all the right serial adaptors
for 9-pin and 25-pin sockets and coping with the need for cable crossover.
This cable has a DPDT toggle
switch to take care of the crossover
and each end of the cable has 9-pin
and 25-pin connectors in both male
and female, so you will always have
the correct connector available.
To use it, connect both computers
and power on. If both LEDs are lit,
then the crossover setting is correct.
If not, change the toggle switch setting and when both LEDs are lit,
6A4/P600G
A
+12V
K
+
GND
GND
4.7k
+5V
PIN 14
PS 'ON'
S1a
A
3 x 3300 F
35V
24V
LED1
K
+12V
GND
–
GND
+5V
LED
K
A
PIN 14
PS 'ON'
S1b
ON/OFF
34 Silicon Chip
3
6
17 5
24 12
ATX POWER
SUPPLY 2
2
18 6
23 11
ATX POWER
SUPPLY 1
2
9
2 14
14 2
1
6
8
8
5
DB9-F
1
7
9
5
DB9-M
6A4/P600G
A
K
communication can proceed.
The two 4.7kΩ resistors limit
the LED currents to about 2mA, to
avoid excessive loading of the RS232 signal.
Russell Horswood,
Maroochydore, Qld. ($30)
Recycled PC power
supplies deliver 24V
This simple circuit shows how two
ATX computer power supplies can be
operated with their 12V outputs connected in series to deliver 24V at a high
current (depending on the ratings of
their 12V outputs). Essentially, the two
12V outputs are connected in series
and both power supplies need to be
started simultaneously by grounding
their start inputs, with a momentary
contact DPST switch (S1).
Before the supplies are connected
together, first check that each one is
working. To do this, apply 230VAC
to their input and monitor the voltage
(+5V) on pin 9 of the 20-pin socket.
Then connect pin 14 of the same connector to GND and the internal fan
siliconchip.com.au
+12V FROM
IGN. SWITCH
FUSE 5A
RELAY
3x 1N5404
K
D1
A
ALTERNATOR
LIGHT
K
A
K
A
K
A
+12V FROM
BATTERY +
FROM
CATHODE
-ANODE
JUNCTIONS
OF STATOR
DIODES
K
FIELD
COIL
D2
620
K
100 F
25V
ZD1
13V
1W
A
A
1k
C
B
B
C
E
1k
Q2
BD139
E
Q1
BC337
C
B
Q3
2N3055
E
1k
CHASSIS
D1, D2: 1N4004
ZD1
A
A
K
K
Voltage regulator for
Mitsubishi van
This circuit was produced to
replace a failed voltage regulator
on an old Mitsubishi Express van
in order to avoid the high cost of a
replacement module. It works the
same as a conventional regulator
on a typical alternator in that the
current through the field winding is
varied to keep the alternator’s output
voltage within a narrow range.
The battery voltage is monitored
via a 5A fuse and the contacts of
the relay. It is then filtered with a
100µF 25V capacitor and fed via a
620Ω resistor to a 13V zener diode
(ZD1) which biases transistor Q1. It
works as follows:
When the battery voltage is below
should run. Check the 5V and 12V
outputs on both supplies.
The circuit includes three 3300µF
35V capacitors to provide additional filtering. Schottky diode D1
is included to prevent the capacitors
from discharging back into the ATX
supplies when power is removed.
You can use HDD sockets with four
siliconchip.com.au
E
C
E
C
B
C
2N3055
B
B
1N5404
A
BD139
BC337
K
E
13.6V, no current flows through ZD1
to the base of Q1, which remains off.
This allows transistor Q2 to conduct
and bias on Q3, a 2N3055 power
transistor. This supplies maximum
current to the field coil of the alternator, to maximise current to the car’s
electrical system and to the battery.
As the battery voltage progressively rises above 13.6V, Q1 is turned
on and it throttles back Q2 & Q3,
reducing the field current and thus
the alternator’s output. The result is
that the regulator holds the output
voltage close to 14.2V when the engine is above idle speed, even with
100W of driving lights and other
loads on the system.
The unit was built on a PCB and
installed in a diecast aluminium box
which acts a necessary heatsink for
the 2N3055. The failed regulator
was left in situ in the alternator case
with its terminations cut off. The
three 1N5404 diodes connect to the
alternator’s stator leads.
With this circuit, there is some RF
interference affecting the reception
of distant AM stations. This can be
remedied by fitting a suppressor to
the B+ terminal on the alternator (if
one is not already fitted). Shielding
the flying leads can help in stubborn cases.
Geoff Coppa,
Toormina, NSW. ($60)
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$
$
contribution
$
$
$
$
$
$
$ As you can see, we pay $$$ for contributions to Circuit Notebook. But $
$
$
$ each month the best contribution (at the sole discretion of the editor) $
$
$
$ receives a $150 gift voucher from Hare&Forbes Machineryhouse.
$
$ That’s yours to spend at Hare&Forbes Machineryhouse as you see fit – $
$
$
$ buy some tools you’ve always wanted, or put it towards that big
$
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$
purchase
you’ve
never
been
able
to
afford!
Contribute
NOW
and
WIN
!
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email your contribution now to editor<at>siliconchip.com.au or post $
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May the best man win!
power supply leads (+5V, GND,
GND, +12V) for connecting and
feeding devices.
Note that in many cases, you will
need to internally discnnect the
output ground from earth for this
arrangement to work. Otherwise,
you will effectively be shorting the
output of one supply to ground. This
connection is often made through a
screw from the PCB to chassis.
Alexey Uskov,
Vladivostok, Russia. ($40)
Silicon Chip Binders
H Each binder holds up to 12 issues
Price: $A14.95 plus $A10.00 p&p each. Available in
Australia only. Buy five and get them postage free.
August 2012 35
The
Driveway
Sentry Mk.2
Here’s an improved version of the Driveway Sentry we described in
the November 2004 issue of SILICON CHIP. It detects vehicles like cars,
trucks, tractors or other farm machinery moving along a driveway
or through a gateway. When movement is detected, it switches on a
mains-powered or battery-powered lighting system and activates an
optional piezo buzzer alarm for a preset period ranging from 2-25
seconds.
The Driveway Sentry
Mk.2 circuit is housed in
a plastic zippy case and
switches on lights when
a vehicle drives over a
driveway detector loop.
By Jim Rowe
36 Silicon Chip
siliconchip.com.au
+V
+V
HIGH GAIN
AMPLIFIER
LP
FILTER
SENSOR
LOOP
IC1,
IC2a/d
LOOP
TERMINATION
BOX
+V
+V
–
START
EXIT
DELAY
IC2b
Q2
RELAY
TEST
BUZZER
ON/OFF
TRIGGER
EXIT
DELAY
HOLDOFF
EXIT DELAY
TIMER
PIEZO
BUZZER
COMPARATOR
+
+V
ALARM
ONE SHOT
Q3
IC5
IC3, IC4, Q1
Fig.1: block diagram of the Driveway Sentry. The sensor loop detects a vehicle passing over it and the resulting signal
is filtered, amplified and fed to comparator stage IC2b. This then triggers a monostable which turns on transistors Q2
& Q3 to drive a buzzer and activate a relay to switch on the lights.
U
NLIKE OTHER motion-sensing
systems that use light, heat or ultrasonic sound waves to detect motion,
the Driveway Sentry Mk.2 operates by
sensing small changes in the Earth’s
magnetic field – the same magnetic
field that’s sensed by a compass.
Since cars, trucks and similar vehicles contain a significant amount
of ferrous metal (iron, steel etc), they
inevitably produce small temporary
changes in the Earth’s magnetic field
when they move into or through an
area. That’s how the original Driveway Sentry detected them and that’s
how this new Mk.2 version works too.
The original unit used a special highsensitivity shielded remote sensor
unit (no longer available) but this new
version simply uses a loop of sensing
cable buried under the driveway.
No interference
Because it doesn’t generate any sensing fields of its own, the Driveway Sensor Mk.2 produces no electromagnetic
interference; it’s quite “clean”. Also,
because it only senses moving iron and
steel objects like vehicles, it’s much
more selective than other kinds of
sensor. This makes it virtually immune
to false alarms from birds, dogs, cats,
sheep, kangaroos and other animals,
falling tree branches, rain and snow,
people walking past (unless they’re
Iron Man!) and so on.
At the same time, it can be used
to detect the movement of vehicles
which contain very little steel – like
aluminium trailers, boats and caravans
– simply by attaching a strong magnet
siliconchip.com.au
Main Features
The Driveway Sentry Mk.2 detects moving vehicles by sensing the small temporary
changes in the Earth’s magnetic field caused by this motion. It detects the changes
using a rectangular sensor loop which is buried under the driveway, or concealed
with two opposite ends of the loop in the expansion gaps in the driveway itself.
Exit Delay: allows the system to be switched to non-sensing “sleep mode” for a
period of about five minutes, to allow the owner’s vehicle to exit from the property
without activating the Driveway Sentry. At the end of the Exit Delay, the system
returns to its movement sensing mode.
Test Button: allows the system to be manually triggered into “movement detected”
alarm mode without having to drive a vehicle over the remote sensing loop. This
makes system adjustment easier and more convenient.
Piezo Buzzer: produces a high-pitched sound to attract your attention when
movement is detected. This sound can be disabled if you prefer the system to
respond silently.
Relay Contacts: includes an SPST relay with mains-rated contacts. The relay is
activated when the system detects movement, allowing the unit to be connected
to control mains lighting or other equipment such as a high-powered siren.
Alarm Duration Control: allows the duration of the system’s “movement detected”
alarm mode to be adjusted between a minimum of two seconds and a maximum
of about 25 seconds.
Sensitivity Adjustment: allows the sensitivity of the Driveway Sentry to be adjusted
over a wide range, so it can be set for reliable vehicle detection without being too
sensitive and susceptible to false alarms.
Low Power Consumption: unit operates from 12V DC power (normally a plugpack),
with a low current drain: <25mA in Exit Delay mode (<300mW), <15mA in armed
mode (<180mW) and <100mA in alarm (movement detected) mode (<1.2W). This
means that the system can also be operated from a 12V SLA battery and/or solar
power in rural and other remote situations.
to the underside of their chassis. The
magnet ensures that if they’re moved
past the Driveway Sentry’s remote sensor loop, the Earth’s magnetic field will
be disturbed locally and the system
will activate.
In short, like the original Drive-
way Sentry, this new version has a
multitude of motion-sensing uses
around the home or farm. The system
operates from 12V DC and draws very
little current – less than 15mA when
armed and waiting, and no more than
100mA when it senses movement and
August 2012 37
FARADAY
SHIELD
470
+5.7V
100nF
10k
SENSOR
COIL
SENSOR
INPUT
5
3
3
2
4
1
4
3
100
1k
2
1
+6V
22nF
4.7k
5
SENSITIVITY
1 F
1k
100nF
8
1
4.7k
VR1 500
2
CON1
7
IC1
AD623AN
22k
6
4
3
5
4
1
IC2a
2
470nF
22nF
30m SCREENED
2-CORE CABLE
10 F
10k
100nF
+6V
+6V
D3
1N4148
K
100nF
100k
6
A
100k
100nF
14
IC3b
13
4
S2
8
100nF
IC3c
7
RS RT
11 10
470k
27k
CT
9
Vss
8
DRIVEWAY SENTRY MK2
EXIT
DELAY
LED2
A
O14
3
K
150nF
10nF
SC
3
560
10k
2012
IC3a
2
IC4 4060B
MR
10
1
IC3: 4011B
16
Vdd
12
9
11
12
5
EXIT
DELAY
IC3d
B
C
E
Q1
PN100
1N4148
A
K
Fig.2: the circuit uses five low-cost ICs. IC1 (AD623AN) provides most of the signal gain for the loop sensor signals,
while 7555 timer IC5 forms the monostable. Counter stage IC4 and its associated circuitry provide an exit delay.
is “alarmed” or activated. Thus it can
be operated from a 12V battery and/or
solar power as an alternative to a DC
plugpack supply.
How it works
The heart of the Driveway Sentry
Mk.2 is a rectangular loop of shielded
multi-conductor cable. This can either
be concealed in the expansion joints
of a driveway or laid under the driveway or gateway to be monitored. The
ends of the loop are fed into a small
waterproof box, where the starts and
finishes of the various conductors are
terminated to form a multi-turn loop.
When tiny, low-frequency AC voltages are induced in the loop turns as
a result of magnetic field disturbances,
they are fed back to the Driveway
Sentry’s main box via a twin-shielded
38 Silicon Chip
cable, amplified and used to trigger the
alarm circuit.
Because the sensor loop also tends
to pick up a significant amount of
electrical noise, it needs to have a
Faraday shield. This job is done by
the screening layer of the loop cable
which is connected (at one end only)
to the shield braid of the output cable.
This provides an electrostatic shield
without also forming a shorted turn.
Fig.1 shows how it works. The tiny
voltages induced in the loop are first
passed through a fairly drastic lowpass filter to attenuate all noise, hum
and spurious signals above about
13Hz. This is possible because the signals we want to detect are of a very low
frequency – only a few Hertz. The filtered signals are then fed to a high-gain
amplifier (IC1, IC2a & IC2d), where
they are amplified by up to 500,000
times. They are also further filtered,
giving an overall attenuation of about
40dB for any spurious signals at 50Hz
and above that may be picked up.
The amplified signal is then biased
to a DC level of 3V and fed to one
input of a comparator (IC2b). Here it
is compared with a reference DC voltage of 4.4V at the second comparator
input. When the peak value of the
amplified sensing loop signal exceeds
this reference level, the output of the
comparator switches low.
The resulting negative-going pulse
is then used to trigger IC5, a monostable pulse generator (or one-shot).
When this happens, the output of the
one-shot switches high, turning on
transistor Q3 and energising the relay.
The relay contacts can be used to
siliconchip.com.au
OUT
470nF
4.7k
220k
1k
220 F
D1 1N5819
REG1 7806
+6V
+11.7V
IN
GND
VR2 500k
47 F
16V
68k
100nF
IC2d
12
POWER
LED1
1k
14
6
7
IC2b
5
+4.4V
TEST
S1
100nF
12V
– DC IN
1000 F
25V
A
IC2: LM324
10
220k
180k
9
IC2c
WARNING: WIRING INSIDE
THIS AREA OPERATES AT
230VAC. CONTACT COULD
BE FATAL!
8
IEC MAINS
INPUT PLUG
TRIGGER
FUSE 1
+6V
47k
VR3
500k
100nF
ALARM
DURATION
8
IC5
7555
7
2
5
–
MAINS
OUTLET
RELAY1
A
LK1
1N4004
K
switch power to a siren, turn on security lights or trigger a security system.
At the same time, the high level at the
output of the one-shot can be used to
turn on transistor Q2 which activates
a small piezo buzzer mounted in the
Driveway Sentry’s control box. However, if you don’t want this internal
buzzer to sound, it can be disabled.
The TEST pushbutton switch can be
used to temporarily ground the positive input of comparator IC2b. This
forces the comparator’s output low,
triggering the one shot in the same
way as a signal peak from the high-gain
amplifier. So the TEST button allows
you to do things like adjust the alarm
duration without having to drive a
vehicle over the cable loop.
As shown in Fig.1, the rest of the
circuitry is used to provide the Sentry’s
N
A
10k
B
C
E
1N5819
A
K
Q2
PN100
B
E
B
E
“Exit Delay” function. This operates by
holding off the one-shot for a fixed period of about two minutes after power
is first applied to the Driveway Sentry
or after the “START EXIT DELAY”
pushbutton is pressed at any later time.
With the one-shot prevented from triggering during that time, you are able to
leave in your own vehicle before the
Driveway Sentry is re-armed.
Circuit description
Now let’s have a look at the full
circuit in Fig.2. The sensor loop is at
upper left. For clarity, it’s shown with
only two turns, although with the
recommended 9-conductor screened
cable there will actually be nine turns.
The loop is connected to the input
of the main circuit in the Driveway
Sentry via a length of screened 2-core
7806
BC337
B
C
E
Q3
BC337
PN100
K
A
C
4.7k
LEDS
siliconchip.com.au
E
K
D2
1N4004
BUZZER
ON/OFF
100nF
A
N
+11.7V
3
1
47 F
RBLL
100
PIEZO
BUZZER
A
10A
+
4
6
+
K
11
+3.0V
CON2
A
1.5k
TRIGGER
SENSITIVITY
13
K
E
GND
IN
C
GND
OUT
cable. This ends in a 5-pin DIN plug
which mates with input socket CON1,
a 5-pin DIN socket.
The very weak signals from the sensor loop then pass through the main
low-pass filter, formed by two 4.7kΩ
resistors, two 22nF capacitors and a
1μF capacitor. They are then fed to the
inputs of IC1, an AD623AN instrumentation amplifier which provides most
of the signal gain. The 100Ω resistor
and 500Ω trimpot (VR1) connected
between pins 1 & 8 of IC1 allow its
gain to be varied between 168 and 1001
times, without significantly changing
its common-mode rejection.
Note that the sensor loop’s Faraday
shield and the input cable’s shield
are not connected directly to earth
but instead go to the half-supply bias
voltage that’s fed to both inputs of
August 2012 39
TRIG SENS
100nF
VR2
500k
+
10k
220k
1k
TEST
220 F
IC2
LM324
S1
1000 F
D2
4004
CON3
IC5
7555
4011B
100
LK1
10k
47k
100k
100nF
POWER
VR3
100nF
100nF
100nF
IC3
100nF
4060B
4148
27k
470k
1.5k
D1
5819
12VDC IN
LED1
REG1
7806
+
D3
IC4
BUZ
+
LED2
NO BUZ
47 F
LL
EXIT
DELAY
500k
S2
Q2
EXIT DELAY
PN100
+
CON2
500
100k
150nF
SENSITIVITY
Q3
BC337
4.7k
1 F
68k
22nF
22nF
10nF
VR1
100nF
10k
220k
22k
470
4.7k
100
1k
4.7k
4
1k
CON1
IC1
AD623
TO EARTH TERMINAL
OF GPO SOCKET
4.7k
470nF
+
5
SENSOR IN
10k
YRT NES YAWEVIRD
2 1 0 2 © 2 KRA M
12170130
1k
470nF
180k
100nF
100nF
560
10 F
Q1
PN100
47 F
100nF
TO RELAY COIL LUGS
PIEZO BUZZER
Fig.3: install the parts on the PCB as shown on this parts layout diagram. Take care to ensure that all polarised parts
are correctly orientated and be sure to make the leads to the relay coil lugs at least 80mm long.
IC1. This bias voltage is derived from
a voltage divider consisting of two
10kΩ resistors and is bypassed using
100nF and 10µF capacitors. It’s then
used to bias IC1’s inputs via the 1kΩ
resistors connected between pins 2 &
3 and 2 & 1 of CON1.
This means that there is virtually no
DC voltage between the sensor loop
conductors and their shielding, which
improves the noise performance.
The amplified signals from IC1
emerge from pin 6 and then pass
through another low-pass RC filter
formed by a 22kΩ resistor and a 470nF
capacitor. They then pass through IC2a,
one section of an LM324 quad op amp
that’s used as a buffer to ensure that
this RC filter is very lightly loaded.
The buffered signals are then fed to the
inverting input of IC2d via a 1kΩ resistor and a 220µF coupling capacitor.
IC2d provides the rest of the signal
amplification, with its gain adjustable
between five and 500 times via trimpot
VR2. It also acts as a low-pass filter
due to the 470nF feedback capacitor.
Its -3dB point varies with the gain setting so that only signals below 40Hz
are amplified.
Note that IC2d only amplifies the AC
component of the signals, with their
mean value set to +3.0V by a voltage divider consisting of two 220kΩ resistors.
From there, the greatly amplified
signal from pin 14 of IC2d is fed via a
40 Silicon Chip
1kΩ resistor to pin 6 of IC2b, configured as a comparator. Here it is compared with a +4.4V reference voltage at
pin 5, as set by a 68kΩ/180kΩ voltage
divider. When the signal applied to pin
6 of IC2b exceeds this +4.4V reference
level, IC2b’s output (pin 7) switches
low, providing a trigger pulse for
monostable IC5, a 7555 CMOS timer.
The trigger pulse from IC2b is fed to
pin 2 of IC5, while pins 6 & 7 are tied
together and connected to a timing
circuit consisting of a 47kΩ resistor,
trimpot VR3 and a 47µF low-leakage
capacitor. VR3 allows the one shot’s
“alarm time” duration to be adjusted
from about 2-25 seconds.
When IC5 is triggered (ie, pin 2
pulled low), its output at pin 3 switches high. This turns on Q3 which in
turn activates Relay1 to switch power
through to the GPO mains outlet. At
the same time, Q2 is turned on to activate the piezo buzzer, provided link
LK1 is set to its upper position.
Exit delay
The exit delay circuit consists of a
simple RS-flipflop (IC3b & IC3c) plus
IC4, a 4060B 14-stage binary divider
with its own clock oscillator. When
power is first applied or when S2 is
pressed, the flipflop is switched into
its reset state (pin 4 low) by the temporary low on pin 8. This low on pin
4 is applied to the reset pin (pin 12) of
IC4 and as a result, IC4 starts counting.
At the same time, gates IC3d and
IC3a (used here as inverters) apply a
logic low to pin 4 of IC5, its reset input.
This prevents IC5 from triggering in
response to pulses from IC2b.
The timer’s counting proceeds for
a little over two minutes, after which
IC4’s O14 (pin 3) output finally goes
low. This negative-going pulse is coupled via a 10nF capacitor back to pin
6 of IC3b, which switches the flipflop
back into its set state.
When this happens, pin 4 goes high
and switches IC4 back into its reset
state, thus stopping its oscillator and
counter. At the same time, gates IC3d
and IC3a apply a logic high to the reset
pin of IC5, allowing it to be triggered
again by any low-going pulses from
IC2b. So the Driveway Sentry is armed
(or re-armed) after a 2-minute delay.
If you want a longer exit delay,
simply replace the 150nF capacitor
with a higher value (eg, 330nF for
five minutes).
During the exit delay time, there is a
logic high on pin 10 of IC3c, the lower
flipflop gate. This is used to turn on
transistor Q1, which allows current
to flow through LED2. This LED is
therefore only illuminated during the
exit delay period.
Power supply
The power supply section of the
siliconchip.com.au
This view shows the completed PCB, ready
for installation in the case. Note that the two
LEDs must be stood off the board by 20mm
(see text) so that they later protrude through
matching holes in the front panel (case lid).
Driveway Sentry is very straightforward. Power comes from an external
12V DC plugpack, with Schottky diode
D1 providing reverse polarity protection. The output from D1 is decoupled
using a 1000µF electrolytic capacitor
and then fed to regulator REG1 which
provides a stable +6V supply.
This +6V rail powers all of the
circuit except for the relay which is
powered directly from the cathode
of D1. Diode D2 across the relay coil
protects Q3 from damage by quenching
any back-EMF spikes that are generated when the relay turns off.
LED1 provides power-on indication,
with the 1.5kΩ resistor limiting the
current through the LED to about 7mA.
x 113 x 63mm. As stated, the remote
sensor loop and its associated termination box connect to the main unit via
a 2-core shielded cable.
Construction
The assembly is straightforward
with most of the parts mounted on a
PCB coded 03107121 and measuring
140 x 84mm. The only parts not on the
board are the remote sensor loop, the
output relay and the mains input and
output connectors.
With the exception of the sensor
loop, the parts are all housed in a
standard UB2 jiffy box measuring 197
Table 2: Capacitor Codes
Value
1μF
470nF
150nF
100nF
22nF
10nF
µF Value
1.0µF
0.47µF
0.15µF
0.1µF
.022µF
.01µF
IEC Code EIA Code
1μ
105
470n
474
150n
154
100n
104
22n
223
10n
103
Table 1: Resistor Colour Codes
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
siliconchip.com.au
No.
1
2
1
2
1
1
1
1
4
4
1
4
1
1
2
Value
470kΩ
220kΩ
180kΩ
100kΩ
68kΩ
47kΩ
27kΩ
22kΩ
10kΩ
4.7kΩ
1.5kΩ
1kΩ
560Ω
470Ω
100Ω
4-Band Code (1%)
yellow violet yellow brown
red red yellow brown
brown grey yellow brown
brown black yellow brown
blue grey orange brown
yellow violet orange brown
red violet orange brown
red red orange brown
brown black orange brown
yellow violet red brown
brown green red brown
brown black red brown
green blue brown brown
yellow violet brown brown
brown black brown brown
5-Band Code (1%)
yellow violet black orange brown
red red black orange brown
brown grey black orange brown
brown black black orange brown
blue grey black red brown
yellow violet black red brown
red violet black red brown
red red black red brown
brown black black red brown
yellow violet black brown brown
brown green black brown brown
brown black black brown brown
green blue black black brown
yellow violet black black brown
brown black black black brown
August 2012 41
OUTPUT CABLE TO
SENTRY CONTROL BOX
CABLE GLAND
NYLON CABLE TIE
IP65 SEALED ABS ENCLOSURE
115 x 65 x 40mm
(SHOWN WITH LID REMOVED)
WIRE SOLDERED TO PCB
COPPER UNDERNEATH
SHIELD
F9, O2
S9, F8
S8, F7
OUTPUT CABLE SHIELD, PCB
COPPER & LOOP SHIELD AT
FINISH END JOINED AT
RH END TERMINAL
NOTE: LOOP CABLE
SHIELD NOT CONNECTED
AT THIS END
CABLE GLAND
'START' END OF
SENSOR LOOP
S7, F6
S6, F5
S5, F4
S4, F3
S2, F1
S3, F2
S1, O1
SENSOR LOOP TERMINATION BOARD
CABLE GLAND
NYLON
CABLE
TIES
'FINISH' END OF
SENSOR LOOP
Fig.4: here’s how to connect the wires from the sensor loop and the output
cable inside the loop termination box. The 12-way terminal block is mounted
on a 104 x 38mm piece of blank PCB material. Note that an earth wire must
be soldered to the copper on the underside of the PCB and connected to the
earth screw terminal at far right.
Below: inside the loop termination box.
Use cable glands and silicone to seal the
cable-entry points, to keep moisture out.
42 Silicon Chip
Fig.3 shows the parts layout on the
PCB. Begin the assembly by fitting the
five wire links (or 0Ω resistors) to the
board (note: if you have a double-sided
PCB, these links aren’t required). The
resistors can then be installed, taking
care to install the correct value at each
location.
Table 1 shows the resistor colour
codes but you should also check each
resistor using a DMM before installing it.
Follow with the non-polarised capacitors, then fit the polarised (electrolytic) capacitors. Make sure you fit
the latter with the correct orientation,
as shown on Fig.3. In particular, note
that there are two different 47µF electrolytics. One is a low-leakage (RBLL)
type and this goes in just below IC5.
The other is a standard RB type and
this is installed just to the right of
REG1.
Now fit the five IC sockets, taking
care to orientate their notched ends
as shown on Fig.3. In particular, note
that IC1 & IC2 face in the opposite
direction to IC3, IC4 & IC5.
The diodes and transistors can now
be installed. Be sure to orientate these
parts correctly and take care not to
get the transistors mixed up (Q3 is
the BC337). Follow these with REG1,
which is mounted horizontally at
lower left. Its installed by first bending its leads down through 90° some
6mm from the device body. That done,
it must be attached to the PCB using
an M3 x 6mm machine screw, star
lockwasher and nut before soldering
its leads to their respective pads.
Next on the list are the three trimpots (VR1-VR3) and the piezo buzzer.
Note that the PCB provides multiple
mounting holes for the buzzer, to cope
with different buzzer pin spacings.
Follow these parts with the 3-way
SIL header strip for LK1, then install
input socket CON1 and the 2.5mm DC
power socket CON2. Make sure these
parts are seated flush against the PCB
before soldering their pins.
The two LEDs can now be installed.
These must be orientated as shown
(ie, with the longer anode lead to the
top). They must also be stood off the
board by 20mm. This can be done by
pushing each LED down onto a 20mmhigh cardboard spacer that’s inserted
between its leads before soldering the
connections.
You can now complete the PCB assembly by plugging the five ICs into
siliconchip.com.au
their sockets. Be sure to install the
correct IC at each location and make
sure they are correctly orientated (IC1
& IC2 face in the opposite direction to
IC3-IC5). Note also that IC3, IC4 & IC5
are all CMOS types, so take the usual
precautions to minimise the risk of
electrostatic damage. If possible, earth
yourself before picking them up and
avoid touching their pins.
The Driveway Sentry’s PCB assembly is now ready for testing.
IEC MAINS INPUT
CONNECTOR (FUSED)
INSULATE METAL
STRIP WITH
SILICONE
SEALANT
E
N
A
NYLON
CABLE TIES
A
N
E
Test and set-up
For the initial testing, there’s no
need to connect the remote sensor
loop to the PCB assembly. However,
you will need to temporarily connect
a 27Ω resistor between pins 1 and 3
of CON1 as a passive “stand in” (ie,
between the two outer pins).
That done, connect a plugpack or
another source of 12V DC to the DC
input socket (CON2). If all is well, both
LEDs should immediately light – LED1
to indicate that power is present and
LED2 because the exit delay timing
circuit has begun counting.
LED2 should now remain on for
about two minutes after power-up.
Similarly, it should also light and remain on for about two minutes after
you press button S2.
Next, set trimpot VR3 to about
midrange and check that link LK1 is
in the “buzzer” position. Now wait
until LED2 goes out, showing that
the exit delay circuit has timed out,
then press TEST button S1. The piezo
buzzer should immediately sound for
about 10 seconds.
If the buzzer operating time is not
to your liking (ie, it’s too short or too
long), this can be easily changed by
adjusting trimpot VR3. The adjustment
range is from about 2s up to about 25s.
The only other adjustment to be
made to the Driveway Sentry is to vary
the sensitivity of the sensor loop. This
is done by adjusting trimpots VR1 and
(if necessary) VR2 after the system has
been installed and the remote sensor
loop connected.
For the present, set VR1 fully anti
clockwise and VR2 to midrange.
GP OUTLET, PANEL MOUNTING
(REAR VIEW)
RELAY
NYLON SCREWS
NYLON SCREWS
EARTH LEAD
CONNECTS TO
CENTRE OF
SCREW TERMINAL
BLOCK ON PCB
RELAY COIL LUGS
CONNECT TO END
TERMINALS OF SCREW
TERMINAL BLOCK
ON PCB
(1) INSULATE METAL STRIP ON IEC SOCKET WITH NEUTRAL-CURE SILICONE SEALANT
(2) SECURE IEC SOCKET & RELAY TO CASE WITH NYLON SCREWS, NUTS & WASHERS
(3) COVER MAINS WIRING WITH PRESSPAHN INSULATION
Fig.5: install the mains wiring as shown here. Be sure to use mains-rated
cable for these connections and make sure that all connections are securely
crimped. The wires must also be routed and strapped to the tabs on the
mains outlet socket using cable ties as shown in the photo below, so that it’s
impossible for a wire to come adrift and contact other wiring.
Below: route the mains wires and secure them with cable
ties as shown in this photo (note: Fig.5 doesn’t show the
exact routing for the sake of clarity). Be sure to insulate
the metal strip on the IEC socket with silicone sealant.
INSULATE
METAL STRIP
Making the sensor loop
As mentioned earlier, the sensor loop
consists of a 25m-length of screened
9-conductor “computer” cable, with
the individual conductors connected in
series to form multiple turns. The free
ends of this multi-turn loop are then
siliconchip.com.au
August 2012 43
PRESSPAHN INSULATION MATERIAL
9
9
9
9
FOLD DOWN 90 o ALONG DOTTED LINE
95
18
13
7
23
20
35
33
35
103
Fig.6: this diagram shows how cut out and fold the Presspahn insulation
material that’s used to cover the mains wiring. Don’t leave it out – it isolates
the mains wiring from the parts on the PCB.
The Presspahn cover has
a cut-out to clear the relay
and is fitted in position as
shown here.
connected to a length of screened twocore extension cable which connects to
the main unit.
In addition, one end of the loop cable
screen (ie, the braid) is connected to the
screen of the extension cable, so that
the Faraday shield can work correctly.
This is all achieved by bringing both
ends of the loop cable and one end of
44 Silicon Chip
the extension (or output) cable into
a small IP65 enclosure, dubbed the
“loop termination box”. This enclosure measures 115 x 65 x 40mm and
houses a small blank PCB fitted with
a 12-way terminal block to facilitate
the various connections.
Fig.4 shows assembly details for
the loop termination box. As you can
see, it’s really very simple, with the
PCB supporting the 12-way terminal
block for the necessary interconnections. The copper under the PCB is
connected to the cable screens (at
terminal 12), to provide a measure of
screening inside the box.
All three cable ends are brought into
the box via cable glands, with the two
loop cable ends entering on one side
and the output cable end entering on
the opposite side. A Nylon cable tie
is fitted tightly around each cable just
after it emerges from its gland, as an
added precaution against the cable
being pulled out accidentally.
Having stripped and secured the
cables to the box, it’s just a matter of
wiring their leads to the screw terminal
block as shown in Fig.4. The wires at
the “start” end of the loop cable are
connected in turn to screw terminals
2-10 on the PCB, while the “finish”
ends are connected to terminals 3-11.
That way, the conductors end up
connected in series, to form a 9-turn
loop with its overall start at terminal
2 and its finish at terminal 11. This
means that the two inner conductors
of the output cable must also be connected to terminals 2 and 11, as shown.
You need to take special care with
the shielding wires and braids, to ensure correct operation of the Faraday
shield. Make sure that the loop cable’s
shield wire at the “finish” end only
is connected to screw terminal 12.
The shield braid of the output cable
is connected to the same terminal.
In addition, a separate lead (shown
green) must be run from this terminal
and soldered to the copper on the
underside of the PCB.
By contrast, the loop cable’s shield
wire is cut short at the “start” end and
is not connected to anything. It can be
covered with a small piece of insulating tape if you wish, so that it cannot
short against anything. Nothing is
connected to screw terminal 1, which
is just a spare connection.
Twist each pair of wires together
before inserting them into the terminal
block. For single wires, you will have
to strip back a little more insulation,
double the wire over and maybe add
a little solder to make it thick enough
to be gripped when the terminal screw
is tightened.
Once it’s all wired up, tighten the
outer sleeve nuts of the cable glands to
make the entry points watertight (add
silicone sealant if necessary). The box
siliconchip.com.au
Use Double-Crimp
Spade Connectors
Note that the spade connectors
used to terminate the mains wiring
must be double-crimp types. This
means that the metal collar inside
each connector extends almost back
to the wire entry hole.
That way, both the bared wires
and the insulation are crimped by the
metal surround, to give better retention. Don’t use single-crimp types
which crimp the copper only, as the
wire can more easily come loose.
lid can then be fitted, along with its
neoprene gasket, and fastened in place
using the screws supplied.
The only step remaining is to fit the
other end of the output cable with a
5-pin DIN plug, to mate with input
socket CON1 on the main Driveway
Sentry PCB. Note that the two inner
conductors must be soldered to pins
1 & 3 of the plug, while the screening
braid goes to pin 2 (ie, the centre pin).
Preparing the case
The drilling details for the box and
its lid are available in PDF format from
the SILICON CHIP website. These should
be downloaded and printed out, after
which the individual sections can be
cut out and used as drilling templates
(they can be temporarily attached to
the box/lid using sticky tape).
Most of the holes can be made by
simply drilling and (if necessary)
reaming them to size. Be sure to always
use a small pilot drill to start the larger
holes, to ensure drilling accuracy.
The two holes for the mains input
and output connectors at the righthand
end of the box are inevitably more
complex. These are best made by first
drilling a series of small holes around
the inside perimeter of the area to be
removed. The holes can then be joined
using a handheld jigsaw, after which
the centre pieces can be knocked out
and the edges de-burred and filed to a
smooth finish using needle files.
Mains wiring
The next step is to mount the relay
inside the case, with its switched output lugs nearest the adjacent end and
the coil terminals towards the middle.
It should be secured using M3 x 12mm
Nylon screws, with metal flat and lock
siliconchip.com.au
Driveway Sentry: Parts List
1 UB2 Jiffy box, 197 x 113 x 63mm
1 PCB, code 03107121, 140 x
84mm
1 110 x 100mm piece of
Presspahn insulation material
1 PCB-mount mini piezo buzzer
2 panel-mount SPST pushbutton
switches
1 PCB-mount 5-pin DIN socket
(CON1)
1 2.5mm concentric DC input connector (CON2)
1 3-way PCB terminal block
(CON3)
1 panel-mount fused IEC male
input connector
1 M205 10A fuse
1 GPO mains outlet, flush panel
mounting
1 12V SPST 20A chassis-mount
mains relay (Ocean Controls
RLY-008)
2 8-pin DIL IC sockets
2 14-pin DIL IC sockets
1 16-pin DIL IC socket
5 6.3mm fully-insulated female
spade connectors (see text)
2 fully-insulated 4.8mm female
spade connectors
1 150mm length of blue insulated
mains-rated wire
1 200mm length of brown insulated mains-rated wire
1 400mm length of green/yellow
mains-rated wire
2 120mm lengths of insulated
hook-up wire
4 M3 x 25mm tapped spacers
9 M3 x 6mm machine screws
4 M3 x 12mm Nylon screws
8 M3 Nylon nuts
1 M3 hex nut
7 M3 star lockwashers
4 M3 flat washers
1 500Ω multi-turn trimpot (VR1)
2 500kΩ horizontal trimpots
(VR2,VR3)
12 small Nylon cable ties
1 150mm length tinned copper
wire
1 3-way pin header
1 shorting link
Semiconductors
1 AD623 instrumentation amplifier
(IC1)
1 LM324 quad op amp (IC2)
1 4011B quad CMOS NAND gate
(IC3)
1 4060B CMOS counter (IC4)
1 7555 CMOS timer (IC5)
2 PN100 NPN transistors (Q1,Q2)
1 BC337 NPN transistor (Q3)
1 7806 6V positive regulator
(REG1)
1 5mm LED, green (LED1)
1 5mm LED, red (LED2)
1 1N5819 Schottky diode (D1)
1 1N4004 1A diode (D2)
1 1N4148 100mA diode (D3)
Capacitors
1 1000µF 25V RB electrolytic
1 220µF 16V RB electrolytic
1 47µF 16V RB electrolytic
1 47µF 25V RBLL low-leakage
electrolytic
1 10µF 16V RB electrolytic
1 1μF MMC
2 470nF MKT polyester
1 220nF MKT polyester
1 150nF MKT polyester
10 100nF MMC or MKT polyester
2 22nF MKT polyester or greencap
1 10nF MKT polyester or greencap
Resistors (0.25W 1%)
1 470kΩ
4 10kΩ
2 220kΩ
4 4.7kΩ
1 180kΩ
1 1.5kΩ
2 100kΩ
4 1kΩ
1 68kΩ
1 560Ω
1 47kΩ
1 470Ω
1 27kΩ
2 100Ω
1 22kΩ
Sensor Loop Assembly
1 IP65 sealed ABS enclosure, 115
x 65 x 40mm
1 blank PCB (ie, copper on one
side), 104 x 38mm
4 M3 x 6mm machine screws
1 12-way barrier screw terminal
block, 96mm long (Altronics
P2130A)
2 M3 x 15mm machine screws and
nuts
3 cable glands (for 3-6.5mm cable)
3 Nylon cable ties
1 25m length of screened 9-conductor “computer cable” (Jaycar
WB-1578)
1 10-30m length (to suit) of
screened 2-conductor heavy
duty microphone cable (Jaycar
WB-1530)
1 5-pin DIN plug, line type
1 50mm-length spaghetti tubing
August 2012 45
STREET END
GAPS BETWEEN
DRIVEWAY SLABS
SENSOR LOOP
LOOP TERMINATION
BOX
HOUSE
OR GARAGE
END
OUTPUT CABLE
TO MAIN SENTRY UNIT
Fig.7: the loop sensor arrangement. The loop can either be buried just under
the driveway or installed in the expansion slots of a concrete driveway, with
the loop sides buried in a shallow trench. The loop termination box and the
output cable should also be buried.
washers under Nylon nuts on the top
of the relay mounting flanges inside
(do NOT use metal screws). A second
Nylon nut at each location is used to
lock the first into position.
That done, use neutral-cure silicone
sealant to insulate the exposed metal
strip on the IEC input connector. That
strip links the Active input pin and
the fuseholder and it runs at mains
potential (230VAC) when power is
applied. So insulating it is a good idea
to prevent accidental contact.
You can now mount the IEC mains
input connector and the mains output
socket on the righthand end of the case.
Use M3 x 12mm Nylon screws to hold
the IEC connector in place, along with
flat washers and two Nylon nuts on
each screw.
Fig.5 and its accompanying photo
show how the mains wiring is installed.
Be sure to use mains-rated cable for
all this wiring. You will need to crimp
6.3mm fully-insulated female spade
connectors to the wires that go to the
relay contacts and to the IEC connector.
In each case, it’s a matter of stripping back about 5mm of insulation
from the wire, then pushing it into
the connector and crimping it with the
tool. Check each crimp connection as
it is made, to make sure it is securely
terminated – you must not be able to
pull the wire out of the connector.
Note that you must use a professional ratchet-driven crimping tool for
this job (eg, Jaycar TH-1829 or Altronics T-1552). Don’t even think about
using a cheap, non-ratchet crimper;
they are not up to the job for a project
like this as the pressure applied to the
connectors will vary all over the place
and this will result in unreliable and
unsafe connections.
Note also that some IEC input connectors have 4.8mm terminals, in
which case you must use 4.8mm spade
connectors to suit. These should also
be fully-insulated types or, if necessary, you can insulate them yourself
using heatshrink tubing.
Once all the spade connectors have
been fitted, plug the leads into the IEC
connector, then connect the Neutral
lead to the GPO mains socket. The lead
from the Active terminal on the IEC
connector is terminated in a second
spade connector and this connects to
one of the relay output terminals. The
other relay output terminal connects
to the Active terminal on the GPO
mains socket.
The two earth leads can now be run
to the GPO mains socket. One of these
leads is run from the Earth terminal on
the IEC socket, while the second lead
is routed back next to this lead and
ultimately connects to the earth track
of the PCB. You will need to make this
latter lead about 250mm long.
Be sure to route the mains wires as
shown in the accompanying photo
(note: Fig.5 shows the connections but
doesn’t show the exact routing for the
sake of clarity). Once all the connections have been made, use cable ties
to strap the wires to the tabs on the
GPO mains socket (see Fig.5). Five
more additional cable ties are also
used to strap the wires together and
should be installed as shown in Fig.5
and the photo.
These cable ties are vital to ensure
that an individual lead can’t come
loose and contact other terminals,
even if the box receives a sudden
jolt. In particular, be sure to strap the
One end of the case carries the IEC input socket and the mains output socket (GPO) while the other end provides access
to the loop input socket, the DC connector and the sensitivity trimpot (VR1).
46 Silicon Chip
siliconchip.com.au
Switching Other Devices
If you don’t wish to switch the mains
then the IEC socket, the flush-mount
GPO socket and the mains wiring can
all be omitted.You can then simply use
the relay output contacts to switch a
low voltage or to trigger some other
piece of gear, eg, a burglar alarm.
Note, however, that it will still be
desirable to earth the Faraday shield
of the loop sensor and this can be
done by running a lead from the PCB
earth terminal to a metal stake driven
into the ground.
The PCB is mounted on the lid of the case on four M3 x 25mm spacers.
Make sure that the extension wires soldered to the switch terminals pass
through their respective holes on the PCB and don’t forget to solder them.
Earth wires to the GPO mains socket
tab and strap the Earth and Neutral
wires together at the IEC connector.
Presspahn cover
As shown in the photos, a Presspahn
cover is used to physically isolate the
mains circuitry from the low-voltage
circuitry and the PCB. This fits vertically over the relay and is folded over
the top of the IEC connector and mains
socket to form a complete enclosure.
Fig.6 shows the dimensions of the
Presspahn cover. It can be cut to shape
using a sharp pair of scissors, while the
hole for the Earth lead that runs to the
PCB can be cut out using a sharp hobby
knife. The fold line is then lightly
scored, after which the top section is
folded down through 90°.
Check the mains wiring carefully
before installing the Presspahn cover.
It’s a good idea to use a multimeter (set
to Ohms) to check all the connections
between the IEC connector and the
mains socket (GPO). The Earth lead
is critical – use the DMM to confirm
continuity between the Earth pin of
the IEC socket and the Earth of the
flush-mounting GPO socket.
siliconchip.com.au
Do the same for the two Neutral
connections (the two Active terminals
should be open circuit since the relay
contacts will be open). Check also to
ensure there are no shorts between
Active & Neutral on both the IEC connector and the GPO socket, or between
either of these two terminals and Earth.
Once that’s done, feed the Earth lead
that runs to the PCB through the hole
in the Presspahn cover. The cover can
then be slipped into position over the
relay (see photos) and secured using
some hot-melt glue or neutral-cure
silicon sealant.
Final assembly
Now for the final assembly. The
first step is to download the front
panel artwork (in PDF format) from
the SILICON CHIP website. This should
be printed out, laminated and attached
to the front panel using double-side
tape or silicone.
The holes in the panel artwork can
then be cut out using a sharp hobby
knife.
Once the panel is finished, mount
the two pushbutton switches (S1 & S2),
then attach four M3 x 25mm tapped
spacers to the back of the box lid at
the PCB mounting points. Secure these
spacers using four M3 x 6mm machine
screws.
That done, cut four 20mm lengths of
0.5mm tinned copper wire and solder
these to the switch terminals. These
form extension leads which will later
pass down through matching holes in
the PCB when the latter is mounted on
the spacers.
Next, cut two 80mm lengths of
medium-duty hookup wire and crimp
one end of each wire to a 4.8mm fullyinsulated spade connector. Check that
these connections are secure, then
connect the opposite ends of these
two leads to the terminal block on the
PCB – see Fig.3.
The earth lead should also now be
connected to the terminal block. Do
the screws on the terminal block up
nice and tight, then fit a cable tie to
the three wires as shown in the photo.
Another cable tie can then be used to
bind the relay wires about 40mm from
the connectors.
The PCB can be mounted on the
spacers on the rear of the lid. Basically, it’s just a matter of offering the
board up to the lid while making sure
that the extension leads from S1 and
S2 pass through their corresponding
PCB holes. At the same time, you have
to make sure that LED1 and LED2 go
through their matching holes in the lid.
Once everything is correct, secure
the PCB to the stand-offs using M3
x 6mm screws and star washers. Do
the screws up tightly, then solder the
extension leads for switches S1 and
S2 to their PCB pads.
The assembly can now be completed by connecting the two spade
connectors to the relay coil terminals,
then carefully lowering the PCB/lid
assembly into the box. Note that it
August 2012 47
affect the sensitivity. If you cannot get
reliable triggering, reverse the loop by
turning it over. This means that you
must test the complete unit before
burying the loop.
VR2, the trigger sensitivity adjustment, is basically a back-up and is
normally left in the midrange position.
It need only be moved from this position if you run out of range with VR1.
Sensor loop installation
This is the completed loop termination
box, together with the sensor loop cable
(light grey) and the extension cable
(black) that runs back to the main unit.
Make sure that the box is properly
sealed against moisture.
will be necessary to bend the leads
from the terminal block straight up
from the PCB so that they will clear
the Presspahn cover. Make sure that
the Presspahn cover is correctly positioned before securing the lid using
the four small self-tapping screws
supplied.
The Driveway Sentry Mk.2 in now
complete and ready for installation
and sensitivity adjustment. Both the
sensitivity control (VR1) and the
trigger sensitivity control (VR2) can
be adjusted after the box is fully assembled, via small access holes (one
in the lid and the other in the lefthand
end of the case).
The same goes for the alarm duration trimpot (VR3).
Sensitivity adjustment
To test the unit, the sensor loop must
initially be laid on top of the driveway
and connected to the main unit. You’re
then ready to adjust the sensitivity.
It’s simply a matter of setting VR2 to
midrange and adjusting trimpot VR1
clockwise to make the Driveway Sentry more sensitive, or anticlockwise to
make it less sensitive.
This will have to be done on a trial
and error basis, with a vehicle driven
over the sensor loop after each adjustment. The best setting is where it
reliably detects the smallest moving
vehicle likely to enter or leave the
driveway but don’t make it more sensitive than necessary. If you simply
adjust VR1 for maximum sensitivity
(ie, fully clockwise), the unit may be
prone to giving false alarms due to
passing radio transmitters or mobile
phones, or during electrical storms.
Note that the loop direction will
The remote sensor loop can either
be buried just under your driveway
(eg, under pavers) or it can be installed
in the expansion joints of a concrete
driveway.
As shown in Fig.7, two of its opposite sides lie in the narrow gaps
between the concrete driveway slabs,
while the other two sides run alongside the enclosed slab on either side.
The loop termination box can be
located adjacent to one side, with the
output cable running away to the main
control box inside your house.
In practice, the loop termination box
can be buried and the output cable run
in a shallow trench back to the house,
so that it doesn’t get damaged. Make
sure that the cable glands have all been
properly sealed using silicone before
burying the loop termination box, to
prevent water damage.
If you are on a rural property, the
loop sensor can simply be buried
under the driveway in a shallow rectangular trench.
Using it
When the Driveway Sentry is armed
and detects movement, it immediately
produces an alarm sound from the
buzzer and operates the relay. The relay contacts can be used to switch on
a security floodlight, other lighting or
perhaps a siren. The Alarm Duration
can be set by adjusting VR3 using a
screwdriver through the front-panel
access hole.
Finally, note that any fixed mains
wiring to lights etc should be installed
SC
by a licensed electrician.
Issues Getting Dog-Eared?
Keep your copies of SILICON CHIP safe with these handy binders
REAL
VALUE
AT
$14.95
PLUS P
&
P
Available Aust, only. Price: $A14.95 plus $10.00 p&p per order (includes GST).
Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648;
or call (02) 9939 3295 and quote your credit card number.
48 Silicon Chip
siliconchip.com.au
EDA
IT
I
UG
Pr
ice
Economy 4 Channel DVR - D1 Resolution
sv
US
Economical DVR for a home or small office. Features 4 channel multiplexer, Ethernet
ali
du
T
functions, and H.264 video compression. It also delivers D1 resolution video (704 x 576) at
nti
100 frames per second. Playback can be displayed locally through the composite or VGA outputs
l
23
and remotely via a network connection using a web browser or an iPhone®, iPad®, or Smartphone
/0
8/
app*. Supplied with a 500GB HDD fitted, software and manual on CD, power supply, and quick start
20
guide. See website for full specifications.
12
ON
NEW
• Built-in web server for network access
• Power supply included
• Size: 375(W) x 285(D) x 45(H)mm
QV-8120
39900
$
NOTE: *Remote access app available for iOS®, Android™,
BlackBerry®, Symbian®, and Windows Mobile® operating systems. See our website for more information.
Also available: 16 Channel DVR QV-8122 $899.00
Soft Start Kit for Power Tools
Ref: SC Mag July 2012
Stops that dangerous kick-back when you first power up an
electric saw, router or other mains-powered hand tool. This
helps prevent damage to the job or yourself
when kick-back torque jerks the
power tool out of your hand.
Kit supplied with PCB, silk
screened case, 2m power
cord and specified
electronic components.
• 240VAC 10A
• PCB: 81 x 59mm
KC-5511
NEW
4995
$
Due Early August
Economy Non-Contact
Thermometer
200WRMS Per Channel
Stereo Amplifier
HOT
PRICE!
2 x 200WRMS channel stereo amplifier with remote
control. Higher power and more features in a standard
Hi-Fi component size.
• AM/FM tuner
• Inputs (Analogue): DVD/CD, Aux 1&2, Phono, DAB, Tape
• Inputs (Digital): Coaxial (2),
optical (2), USB
• Size: 430(W) x 241(D)
$
00
x 114(H)mm
AA-0484
NEW
329
USB Business Card Scanner
Save your business card
contacts directly to an
Outlook/Outlook
Express address
book. Using optical
character
recognition extract
text from the
business card and
categorise it in to 13
different fields.
• Scans single or double
sided business cards
• Size: 120(L) x 70(W) x
20(D)mm
XC-4908 Was $79.95
Safely measure temperature in hot,
hazardous, or hard to reach places
with the built-in laser pointer directed
at the surface. Provides several
readings within seconds. Compact and
easy to use with carry case included.
• 8:1 Distance to spot ratio
• Auto Data Hold
• Temperature range:
-30°C to +260°C
• Size: 131(H) x 96(W) x 35(D)mm
QM-7215
Send AV signals around the house wirelessly without
running wires. Great for transmitting Pay TV to
another room. Exceptional performance and
includes a built-in infrared extender so
channel or volume can be changed
remotely. It even handles the
modern Pay TV remotes. Power
supplies and AV cables
included.
• 5.8GHz DIGITAL technology
• Expandable to multiple TVs
using up to 4 receivers
(sold separately)
• Range: up to 50 metres
• Works with Pay TV remotes
• Size: 150(L) x 112(W) x
110(H)mm (with antenna up)
AR-1878
NEW
9900
$
Additional Receiver AR-1879 $69.00
Colour may vary
PACKAGE DEAL!
DIY Package
& SAVE $$$
NEW
Stainless Steel Side Cutters
4995
32-pce Driver Set (TD-2106 $17.95)
Storage Case (HB-6302 $16.95)
Data-hold DMM with
backlit (QM-1523 $14.95)
$
USB Power Bank with
2600mAh Battery
Features a USB charging port and lead with 3 connectors
for charging all variety of Smartphones, tablets and USB
charged devices. The device itself
NEW
can be recharged with the supplied
$
95
micro USB to USB cable.
• Output lead with 3 connectors
included: Mini-USB, Micro-USB,
Apple® compatible connector
• Size: 76(L) x 33(W) x 29(D)mm
MB-3642
5.8GHz Wireless AV
Transmitter and Receiver
(TH-1890 $13.95)
4995
$
SAVE $13.85
34
NEW Store - Elizabeth
5A, 1 Philip Highway
SA 5112
Ph: (08) 8255 6999
Plenty of parking available!
Network Connect Vandal Proof Mini Dome Camera 2MP
Access your CCTV system via the Internet or your local intranet. This dome camera connects straight to your
existing network for complete control. Access the camera through a web interface by hitting the IP address of
the device and logging in. The web interface allows you to control the camera around 3-axis, zoom,
adjust visual settings, record, take snapshots and setup scheduled recording.
Laptop not included
5995
$
SAVE $20
• Processor: TI DaVinci Series DSP
• Operating System: Embedded Linux
• Video compression: H.264/MJPEG
• CMOS camera sensor, 12VDC, PoE
• Size: 110(Dia.) x 54(H)mm
QC-8626
To order call 1800 022 888
NEW
29900
$
www.jaycar.com.au
HARDCORE DEALS & BARGAINS
Water Powered Vehicle Kit
Build up to 13 different water powered vehicles and
watch them move! This kit demonstrates water jet
power and hydro pneumatic power in a fun and
simple way.
Chassis Mount Solid
State Relays
Inline JST Switch Kit
Includes a JST switch with a male and female JST
connector on each end attached to a 140mm wire.
• Includes mounting bracket and screws
• Switch size: 25(L) x 23(H) x 9(D)mm
SS-0826
NEW
3
$ 95
NEW
3995
$
• Suitable for ages 8+
• Assembly time: 30min approx.
• Size: 370(W) x 290(H) x 80(D)mm
KJ-8913
4 Gauge OFC Super High Current Cable
Run from your battery to distribute
boxes and then 8GA to amps etc.
• Roll length: 50m
• Sold per metre
Adjustable Incandescent
Lamp Flasher
This unit has 4 wires only: 2 to
the mains and 2 to the lamp.
Will electronically
switch on/off from
0.6-9.0 secs adjustable,
lamps from 15-300 watts,
incandescent only.
RED
BLACK
to suit SY-4085 NEW $9.95
Sold per
metre
0 Gauge OFC Ultra High Current Cable
2495
$
Fixed Incandescent
Lamp Flasher
Run from battery to distribution blocks and then 2GA, 4GA or
8GA to your amplifiers or other power equipment for seriously
high current applications.
$
50
• Roll length: 25m
mt
• Sold per metre
SAVE $5
14
RED
BLACK
WH-3092
WH-3094
Was $19.50
Consists of PIN diode, pre-amplifier,
AGC, pass filter, and demodulator.
See website for datasheet.
1995
$
• Supply voltage
max: 6V
ZD-1953
Digital Signal Controllers
• High performance
enhanced flash digital
signla controllers
• 16 bit architecture
See website for datasheet.
225
$
RJ12 Extension Cables
RJ12 6P/4C
• 1.0m YT-6042 $4.95
• 5.0m YT-6049 $7.95
1430
$
dsPIC30F2010
28-pin ZZ-8575 $14.30
dsPIC33FJ128GP802I/SP* 28-pin ZZ-8605 $14.95 NEW
Right Angle Shaft
Coupler (Male)
Basically a right-angle cast housing with 45° Nylon
bevel gears permanently coupled. One
shaft is enclosed with a panelmount style threaded bush.
3995
$
NEW
3
$ 50
ea.
RJ12 6P/6C
• 1.0m YT-6033 $9.95
• 5.0m YT-6034 $12.95
From
495
$
Double -Stage
Classic Style
Universal Joint
(Female)
• Works best between
80 and 45°
• Grub screws fixing
6.0mm diameter shafts
YG-2608 Was $49.95
SAVE $10
To order call 1800 022 888
See website
for video
online
219
• Colour Ivory
From
32.768kHz Crystal
• DT38 • 35 Ohm
• 3.1 x 8mm
RQ-5297
Made in Germany, our
Stirling engine is
beautifully engineered
from stainless steel,
brass and a genuine beech base. It
has 2 ball bearings and should become an
heirloom.
$
00
THIS IS A KIT,
ASSEMBLY
SAVE $30
REQUIRED!
NEW
SAVE $5
PIC30F2010
Microcontroller - DIP28
12MHz Crystal
• HL49U • 30 Ohm
• 11.5 x 4.65 x 13.5mm
RQ-5293
A Stirling engine is a machine that
converts heat into mechanical energy.
The expanding air acts on a piston
to provide mechanical force:
you simply heat up the air
chamber, give the flywheel
a whirl and away it goes.
TSOP4136 IR Receiver
• External fuse & suppressor capacitor
required - use RG-5240 $2.95
• Size: 60(L) x 45(W) x 20(H)mm
AA-0214 Was $24.95
Crystals
Stirling Engine Project Kit
IR LED Receiver
When connected in series
within a 240V incandescent
lamp (up to 600W) the lamp will
turn off and on (95% brightness)
fairly slowly - about once a second
approximately!
2
WH-3064
WH-3066
4795
ea
$
Also available: Heatsink
SAVE $2
Was $8.90
• External fuse & suppressor
capacitor required
SAVE $5
use RG-5240 $2.95
• Size: 70(L) x 50(W) x 40(H)mm with
surface mount lugs
AA-0242 Was $29.95
• Two mounting nuts and a
lock washer are provided
• Nickel plated
• Each shaft is 10mm long
YG-2612 Was $49.95
690mt
$
40A 240VAC Triac Type
This unit has a dielectrically
isolated DC control input that
controls a 40amp TRIAC. This
means that you can control AC
mains up to 40A. It will not control DC.
SY-4084
100A 0-30VDC
MOSFET Type
This unit has a dielectrically
isolated DC control input to
switch a MOSFET which can
control loads of up to 100A <at>
30VDC. It will not switch AC.
SY-4086
• Suitable
for ages 12+
• Adult supervision
recommended
• Size: 156(L) x
108(W) x 70(H)mm
YM-2923 Was $249.00
All-Metal Universal Joint
(Trunnion Style)
Female 6.0 (Dia.)
$
This is a low torque coupler
that will couple offset shafts by
up to 2mm and 15 degrees offangle. Accepts 6mm shafts
with sleeved collet.
SAVE $10
• Nickel plated
YG-2604 Was $24.95
3995
1995
$
SAVE $5
All savings based on Original RRP. Limited stock on sale items.
Prices valid until 23/08/2012.
TOOLS & IT DEALS & BARGAINS
18 Piece Stainless Steel
Mixed Bit Set
You wouldn't think USB could supply enough power
for a usable soldering iron, but it works by using
two USB ports and produces enough heat to be a
viable service tool.
A collection of commonly used
driver bits in a handy rubber
edged case. All stainless steel.
Driver not included.
• Contains: Torx: T10, T15,
T20, T25, T30, T40
Flat blade: 3.5, 5.5, 6.5 Philips head:
1, 2, 2, 2, 3 Hex: 4, 5, 6
$
95
• Case size: 115(L) x
50(W) x 31(D)mm
SAVE $5
TD-2111 Was $29.95
24
9 Piece Folding Key Sets
Ball Allen Key Set Metric
TD-2172 $5.95
Ball Allen Key Set Imperial
595
$
TD-2174 $5.95
Ea
IP67 True RMS Autoranging
Cat IV DMM with Wireless USB
A quality true RMS multimeter with a
wireless USB computer interface and
includes logging software which allows
computer based live data whilst
keeping your computer completely
isolated and protected. Double
moulded housing and IP67 rated.
9900
$
SAVE $10
A simple way to extend speedy wired networking
around the house. The device will convert Ethernet
packets from the Ethernet port to
powerline communication packets
(PLC packets), which run on
regular home power lines, then
converts them from PLC packets
back to Ethernet packets.
129
$
00
10-Port USB Hub
Turn off non-essential
peripherals while
maintaining power to
others with this 10 port USB hub.
The two position switch turns all ports on,
or only ports 7 - 10. 5VDC 3A plugpack
required for powered operation.
• LED indicator
• Size: 172(L) x 36(W) x 27(H)mm
XC-4946 Was $59.95
1495
$
SAVE 10
$
Pocket Sized Non-Contact
Digital Thermometer
• Pocket-sized with LCD
• Temp Range: -35
230°C / -31, 446ºF
• Battery included
• Size: 74(L) x 40(W) x 20(D)mm
QM-7225 Was $34.95
4995
$
SAVE $10
95
SAVE $5
29
95
Make typing and navigation a breeze with
our compact, wireless QWERTY keyboard. Use
Bluetooth® to connect it to a wide variety of mobile
phones, tablets, smart TVs, media centres or PCs.
See website for
more details
NEW
4995
$
USB Lead with 3.5mm Stereo Plug
Use the 3.5mm stereo plug to connect your
iPhone®/iPod® to portable speakers or
Hi-Fi system while charging via USB or
mains adaptor (not supplied).
Connect your device to the
computer to sync with your
personal iTunes® account.
Avoid the mess caused by
two separate cables.
• Cable
length:
1.2m
WC-7695
Better, More Technical
• Voltage: 4.8V
• Bit holder size: 6.35mm
• LED battery level indicator
• Mains charger
included
$
95
TD-2498
FREE POUCH
(TD-2499)
valued
at $5.95
19
DIY Package
& SAVE $$$
Soldering iron starter Kit
(TS-1651 $24.95)
32-piece driver set
(TD-2106 $17.95)
Data-hold DMM with
backlit (QM-1523 $14.95)
Tool set (TH-1812 $29.95)
Storage case
(HB-6302 $16.95)
7995
$
SAVE $24.80
An advanced learning universal
remote control backed
with full QWERTY
keypad that also features
optical finger navigation for
mouse-like control. Perfect for
media players, Smart TVs, home
theatre PCs or gaming.
NEW
• Includes 2 x CR2025 batteries
• Size: 167(L) x51(W) x 15.3(D)mm
AR-1723
3495
$
90W Universal Laptop
Power Supply
An auto-switching laptop power supply with voltage
regulation for added reliability. Features an LCD for
voltage display and a USB port for
charging your phone or MP3 player.
Supplied with 11 different
connectors.
• 90W output
• Size: 126(L) x 55(W)
x 31(H)mm
MP-3326
NEW
Also available: 90W Universal
19
$
1995
Universal Remote Control
with Keyboard
Mini Bluetooth® Keyboard
• Operation
range: 10m
• Includes 2 x
AAA batteries
• Size: 261(L) x 112(W) x 30(H)mm
XC-4945
Due Early August
NEW
$
PACKAGE DEAL!
Features a 5 digit LCD display that will show
readings in metric and in imperial. The caliper can
be zeroed at any point along the scale making
comparative measurements easy. Battery included.
$
• Cat III rated
• LED flashlight function
• Size: 176(L) x 26(D)mm
QP-2268
Easy to use, cordless and has a comfortable pistol
grip that gives you maximum control.
Also features a bright LED lamp, a
magnetic bit holder, and a
handy security strap.
29
$
Detects AC voltages from 200 - 1000V. The unit will
glow green when safe, and when voltage is detected it
will flash red and beep at an increasing rate as you get
closer to the voltage source. It can be used for
detecting live mains in outlets, power boards
or insulated wiring.
4.8V Cordless Screwdriver
Precision Digital Vernier
Calipers
• Stainless steel
• Auto power off
TD-2082
Ethernet over Power - 200Mbps
• Data rate: Up to 200Mbps
• Data link protocol: HomePlug AV
• Size: 115(L) x 59(W) x 26(H)mm
YN-8350
• Pocket-sized
• Power: 4 - 5W
• Size: 120(L)mm
TS-1537 Was $24.95
Featuring an easy to read LCD.
Handy for use in the kitchen or
the food service industry to
ensure proper cooking, grilling
and storage temperatures.
Handy folding sets of Torx or Allen
keys with sturdy anodised aluminium
handles. The handles have M8,
M10, E8 and E10 spanners
built into them.
Buy ALL 3
for $12.00
Torx Key Set
SAVE $5.85
TD-2170 $5.95
• Non-contact voltage
indicator, data hold
• Backlit, auto off
• Diode test and audible continuity
• Cat IV, 600V, 4000 count
• 10A current range
• Size: 170(L) x 79(W) x 50(H)mm
QM-1571 Was $109.00
Non-contact AC Voltage Detector
5W USB Soldering Iron
95
Note: Laptop & iPhone® not included
Slimline Laptop Power
Supply MP-3327 $79.95
www.jaycar.com.au
NEW
7995
$
3
AUTO DEALS & BARGAINS
Bluetooth® Handsfree
Car Kit with LCD
iPhone /iPod Car
Charger/Audio Kit
®
®
Safely dial or answer a call hands-free
whilst driving. Fits unobtrusively to the visor and
features a large LCD screen to display incoming
caller ID and the voice dial function. Connects up
to two phones simultaneously and has a 360
hour standby between
charges. USB cable
& 12V car charger
included.
Modern in-car stereo systems
support a 3.5mm audio-in socket to
play music from popular, portable audio
devices. Listen to your favourite songs
from your iPhone®/iPod® using the
integrated audio cable (with a 3.5mm
stereo adaptor) while charging it via
the supplied cigarette lighter
adaptor.
NEW
• Lead length: 1.2m
MB-3653
2995
$
FM Transmitter with
Detachable MP3 Player - 2GB
Listen to your music on the MP3 player and when
you jump in your car, keep on listening to that
favourite track straight through the FM radio.
Features a built-in MP3/WMA decoding chip that
enables you to play from the stored TF card and
built-in memory. Comes with
USB charging cable and
earphones. See website for
specifications.
• 30mm LCD screen displays
• Operation voltage: 9V-26V
• Approx 230mm
long (including
NEW
MP3 player)
$
95
AR-3123
Detachable
MP3
34
From
5995
$
WAS $69.95 NOW $59.95 SAVE $10.00
WAS $79.95 NOW $69.95 SAVE $10.00
6" 75WRMS CS-2402
WAS $89.95 NOW $79.95 SAVE $10.00
6 x 9" 75WRMS CS-2403
WAS $119.00 NOW $109.00 SAVE $10.00
Sold as a
pair!
Economy Active 12" Subwoofer
9900
$
• Power output: 75WRMS
• Size: 425(W) x 355(H) x 360(D)mm
CS-2269
4
5995
$
Ideal for keeping track of
the temperature when
you're on the road. The
unit plugs into the vehicle's
cigarette lighter socket for power
and also features an inbuilt clock.
Mounts perfectly on your vehicles dashboard
and when not needed, folds down into a
compact shell for dust-protected storage.
With two video inputs, the rear vision view
is automatically activated when your
reversing gear is engaged.
• Crisp high resolution display
• TFT active matrix system
• Auto switching PAL (4.43MHz)
and NTSC (3.58MHz)
• Power: 12VDC 8W
$
QM-3771
SAVE $5
1995
$
• Input voltage: 12-24VDC
• Selectable blue or white LCD display
• Size: 86(L) x 34(H) x 21(W)mm
XC-0114
In-Dash MP3 Player with Radio
BUY BOTH
FOR $129
SAVE $49.95
8900
8995
$
Listen to your favourite MP3s directly from the
USB/SD card slot. Featuring PLL tuner with 18FM/12
AM presets, and MP3/WMA playback you will never
miss a beat with this
in-dash MP3 player.
• Front USB and
SD card slot
• Max 16GB USB, 8GB SD (support HC cards)
• 4 channels x 40W MAX power output
• 4 channels x 20W RMS
power output
$
00
• 2 channels x 2V line-out
QM-3781
79
12VDC Voltage
Polarity Tester
Digital Tyre
Pressure Gauge
Keep track of tyre pressure and avoid pressure
related problems. Measures pressure from 5
to 100PSI and includes an integrated torch
for night time use.
• Includes 2 x AAA
batteries
• Size: 156mm long
QP-2293 Was $19.95
3995
$
Indoor/Outdoor Car
Thermometer with Clock
NEW
3.5" LCD Car Dash-Mount
Colour Monitors
• CMOS camera sensor
QC-3513
5" 50WRMS CS-2401
This 12" Subwoofer in a
sealed enclosure has
a built-in amplifier
to match. The unit
produces a whopping
75WRMS of astounding
bass. Equipped with line
level and high level
inputs, it also has builtin fuse protection and
wired remote level control.
• Input voltage: 10 - 15VDC
• Output waveform: modified sine wave
• Size: 150(L) x 75(W) x 40(H)mm
MI-5125 Was $44.95
Give drivers a clear view of car or truck blind spots. A lengthy
5m composite RCA cable, a 730mm power cable, and
the appropriate sized hole saw are included.
SAVE $10
4" 40WRMS CS-2400
• Noise, echo and
wind suppression
• Size: 185(L) x 136(W) x
65(H)mm
AR-3122
This compact (150mm long) inverter
plugs directly into your vehicle's
cigarette lighter socket to
deliver 230VAC at 150 watts.
Comes with a USB port to
charge or power your MP3
player or other USB operated device.
Flush Mount Mini Waterproof
Camera for Cars or Trucks
Coaxial Car Speakers
Our ever popular Response
Precision Kevlar Coaxial
Speakers that has won many
awards and magazine
recommendations. The speaker
cone is supplied in black and
the soft dome tweeters provide
clean, crisp sound and maintains a
natural and smooth balanced sound.
150W Inverter with USB Outlet
1495
$
19
SAVE $5
G-Force Meter Kit
Measure the g-forces on your vehicle and it's occupants
during your next lap around the race circuit, or use this kit to
encourage smoother driving to save petrol and reduce wear
& tear. Forces (+/- 2g) are displayed on the 4-digit LED
display. Can also be use in measuring g-forces on a boat
crashing over waves or on a theme park thrill ride.
Kit includes PCB with pre-mounted SMD
component, pre-programmed
microcontroller and all onboard
electronic components.
• Requires 2 x AA batteries
• PCB: 100(L) x 44(W)mm
KC-5504
NOTE: We supply the PCB with the SMD
component already mounted on the
board to save time and frustration.
Limited Stock. Not Available Online.
To order call 1800 022 888
A passive, quick and easy testing
solution that performs five
essential tests in the field: voltage,
load, polarity, voltage drop and continuity.
Ideal for CCTV and security installers, car
audio, roadies, AV techs etc.
$
95
• Size: 51(L) x 44(W) x 29(H)mm
SAVE $5
QP-2215 Was $24.95
4995
$
Automotive LED Scrolling
Message Sign
Attach this to the rear window of your car to
display messages to other motorists. Taxi or bus
drivers could use it to communicate vacancy or
destination, emergency traffic control vehicles
could communicate messages to slow down.
Switch between pre-programmed messages
easily with the supplied remote
NEW
control and adjust the scrolling
$
95
speed with ease.
XC-0201
Also available: LED Scrolling Sign with Stand and
Mains Adaptor XC-0202 $59.95
49
All savings based on Original RRP. Limited stock on sale items.
Prices valid until 23/08/2012.
OUTDOOR DEALS & BARGAINS
910 Lumen LED Powered Torch
An immensely powerful yet compact torch that uses
a CREE® XM-L T6 LED for up to 910 Lumens of light
output, making it ideal for heavy duty applications
such as marine rescue, caving, or security. Supplied
with batteries and mains battery charger.
• Light modes: high,
medium, low,
flashing, and
SOS
• Burn time: 1.5 hours (max output)
• Size: 243(L) x 46(Dia.)mm
ST-3480
NEW
9900
$
From
1995
$
Provides far greater accuracy and
reliability. Just blow in the mouthpiece
for a reading in seconds. Same
technology used by law enforcement
for years. Spare mouthpieces available
separately (QM-7303).
29
Suitable power supply SL-2757 $14.95
Caravan/Marine Power
System - 160W Solar
• Green backlit LCD screen
• No licence required
• Requires 4 x AAA
• Size: 115(H) x 65(W) x 35(D)mm
DC-1021
11900
$
NOTE: Readings taken with this device are
Includes FREE
for reference only. In spite of its quality and
accuracy, errors may occur due to operation Spare Mouthpieces
valued
at $4.95
or environmental conditions and we accept
no liability or responsibility whatsoever for any
consequences arising from the use of this device.
Keypad Shed Alarm
1995
NEW
4995
$
710 Lumen CREE® LED
Powered Torch
Features silicone gasket sealed at both ends with a
twist switch at the base to prevent accidental
engagement. High quality rugged aluminium
construction finished in gun metal matte grey/black.
Ideal for outdoor activities.
• Light modes: off, high, low
• Burn time: 8 hours
(3hrs on max
setting)
• Requires
4 x D batteries
• Size: 355(L) x 52(Dia.)mm
ST-3451
Simple and effective shed or garage alarm.
Consists of a keypad, single reed switch and
5m of cable for easy DIY installation. Used as
an instant alarm, with an entry delay or as a
door chime to announce entry. Powered by a
single 9V battery (not included).
7900
$
Buy both
for $45
SAVE
$14.90
Ideal for garages, gazebos
and greenhouses, the 360°
adjustable solar panel will
allow for custom positioning.
Weatherproof and features a
cord-switch to operate.
Installation is simple.
DIY
Package &
SAVE $$$
3995
$
Smart Solar Battery Charger
Supplies 15V at around 100-120mA of current which
is enough to keep an unused 12V battery topped up.
Housed in a plastic case, and has an output lead to
cigarette lighter
plug with a
LED, which
illuminates
when the solar
panel receives
a charge.
• Size: 370(L)
x 160(W) x 20(D)mm
MB-3501 Was $29.95
2kW & 3kW Petrol Generators
Better, More Technical
3890
SAVE $5
Marine growth electronic antifouling systems can cost
thousands. This project uses the same ultrasonic
waveforms and virtually identical ultrasonic transducers
mounted in a sturdy polyurethane housings. By building it
yourself (which includes some potting) you save a
fortune! Standard unit consists of control electronic kit
and case, ultrasonic
transducer, potting and
gluing components and
housings. The single
transducer design of this kit
is suitable for boats up to
10m (32ft); boats longer than
about 14m will need two
transducers and drivers.
Basically all parts supplied in
the project kit including wiring.
(Price includes epoxies).’
• 12VDC
• Suitable for power or sail
• Could be powered by a solar
panel/wind generator
• PCB size: 78 x 104mm
$
00
KC-5498
Now available Pre-built:
249
Dual output, suitable for vessels upto 14m (45ft)
899
NOTE: Not stocked in all stores but our staff can order them in for you.
2495
$
MG-4504
Petrol powered and differ from cheaper units due to the engine
drives a DC alternator. The inverter then converts the DC to a stable
pure sine wave 230VAC. The added benefit is that the petrol motor
is far better matched to the load, reducing overall size, keeping
engine speed in line with the load, reducing noise and increasing
fuel efficiency. See website for full features and specs.
From
2kW MG-4502 $899.00
$
00
3kW MG-4504 $1499.00
The perfect entry level power system for caravans
and boats. Includes everything to make a complete
12V house battery system with enough stored
battery power for short
periods of free camping
without AC power. Includes
a Rich Electric
CombiPlus
1500W-12V
interactive
inverter-charge,
2 x 80W mono
crystalline solar
panels, 150Ah AGM
battery, dual battery
isolator and most of
the accessories
required to round
out the system. See
our website for full details
$
and performance.
MP-9011
Ask our staff for more CARAVAN/MARINE PACKAGES.
Ultrasonic Antifouling Kit for Boats
$
Solar Powered
Garage LED Light
Keep your eyes on the road
and turn safely using our
bicycle indicator kit. Audible
beeps confirm your choice of
direction; one beep for a right turn
and two beeps for a left turn.
Has hazard light function for
road-side emergencies.
• Super Bright
NEW
• Weatherproof
$
95
• Wireless; easy installation no
messy cables
• Handlebar mounts with quick release
• Signal pod requires 3 x AAA batteries
ST-3227
1W 85 Lumens LED SL-2747 $19.95
3W 150 Lumens LED SL-2749 $29.95
This lightweight hand-held transceiver is
suitable for professional and recreational
activities such as hiking, boating,
IT-cablers, electricians, inter-car road
trip communication etc. Open field
transmission range is up to 5km, with
city range up to one kilometre.
Compact Fuel Cell
Alcohol Tester
• Solar panel size:
175(W) x 127(H)
x 15(D)mm
SL-2715
NEW
80Ch 0.5W Transceiver
SB-2403 $19.95
• Size: 162(H) x
85(W) x 32(D)mm
LA-5214
Suitable for lighting up walkways,
water features, or general garden
ambience. Fully waterproof with a
pre-attached 4.5m power cable.
Requires a 12VAC power source.
• IP68 rated
• Size: 50 (Dia). x 38(L)mm
Replacement Li-ion batteries available
• Backlit LCD
• Alert at 0.05%
• Requires 3 x AAA batteries
• Size: 105(H) x 45(W) x 20(D)mm
QM-7302
Bicycle LED Indicator Kit
Waterproof LED
Spotlights
YS-5600 $899.00
MG-4502
Quad output, suitable for vessels upto 20m (65ft)
YS-5602 $1199.00
www.jaycar.com.au
5
SIGHT & SOUND DEALS & BARGAINS
Music Centre with DAB+, USB & iPod® Dock
Acoustic Guitar with USB
Connection
Full size steel string acoustic guitar with laminated
top and sides, built-in chromatic tuner and 3-band
EQ. Suitable for all levels of users. Connect to a PC,
play through an amplifier, mixing desk or PA. Easy
to use recording and editing software included.
Spare strings (pack 6) available separately
(CS-2558 $7.95 ).
• Windows & MAC® compatible
• Magix Music Maker
• Requires 1 x 9V battery
CS-2559
18900
Feature packed with
32 built-in live rhythm
drum patterns, volume, gain,
distortion, overdrive and tone
controls. AUX-IN jack to
connect a CD/MP3 player
and jam with your heroes.
• DAB+ & FM digital radio tuner
• iPod® dock, USB port, SD/MMC card slot
• CD player, aux line-in
• Plays MP3, WMA, CD-R/RW
• Size: 310(W) x 115(H) x 185(D)mm
AR-1752
Buy Both &
Spare Strings for
$290 SAVE
$25.95
Simultaneously connect 2 video sources to a
single HDMI port on your display screen.
Powered from the HDMI
source it automatically
switches to either port
when a signal is present.
• Size: 80(L) x 43(W) x
15(H)mm
AC-1691
Allows you to hook up, convert and switch between
a component video (YPbPr), DVI-Digital, and an HDMI
signal to one HDMI v1.3 output. Includes an IR
remote control and mains adaptor.
11900
$
2.4GHz DIGITAL
Wireless Speakers
Pop this pair of
speakers in the
backyard and the
2.4GHz DIGITAL
audio transmitter
will send crystal
clear audio to the
units up to 30m
away. Each speaker
has its own power adaptor and
operates wirelessly. Power
$
00
adaptor for transmitter and
speakers are included, however
SAVE $30
speakers can also be powered
via 6 x AA (not included) for complete portability.
139
• Speaker size: 250(H) x 130(Dia.)mm
AR-1891 Was $169.00
6900
$
• Output: 1x HDMI v1.3
compliant output +
optical SPDIF digital audio
• Power supply: 5VDC 2A included
• Size: 258(W) x 120(D) x 28(H)mm
AC-1684
Additional emitters:
Single AR-1811 $7.95
Dual AR-1813 $9.95
74 White LED
Strobe Light
• Mountable and mains powered
• Size: 56(Dia.) x 97(L)mm
• Mains powered
• Size: 140(L) x 120(Dia.)mm
SL-3464
Ultra compact mini spotlights
offering a super bright precision
beam. Ideal for fixed lighting
solutions and a range of party
spot light applications to
illuminate and decorate.
NEW
3495
ea.
Due Early August
To order call 1800 022 888
Suitable for frequent flyers and
travellers, these active noise
cancellation headphones will
reduce background noise by
up to 16dB. The ear cups
rotate for compact size and
easy storage inside your handcarry bag or seat pocket.
• High quality digital stereo sound
• Built-in rechargeable battery
• Airplane adaptor
AA-2088
NEW
6995
$
DMX Controller USB Interface
This kit controls DMX fixtures such as spotlights
using a PC and USB interface. It can also be
operated in stand-alone mode that outputs all
512 channels at the same time (9V battery
required for stand-alone mode). Includes
software, USB cable and enclosure.
9900
$
Control a relay with the DMX512 protocol. The relay will be
activated when the DMX value of the set channel equals
140 or more and turns off when the value is 120 or less.
Team it with KV-3610 to make a
computer-controlled automation
system. Short form kit.
From
5995
$
SAVE $20
• 512 unique addresses,
DIP switch settable
• LED indication for power supply,
$
95
relay output and error status
• Relay hold function in
case of DMX signal loss Limited stock. Not available online
KV-3612
29
DMX Control Dimmer Kit
Allows you to control a lamp or group of lamps through a
DMX signal. You can use the USB Controlled DMX Interface
kit or any other control console compliant with the DMX512 protocol as a controller. It will drive resistive loads like
incandescent lamps and mains
voltage halogen lighting.
Shortform kit.
Features 74 super bright white
LEDs with adjustable flash rate.
Lightweight design made from
a strong plastic and supplied
with mounting hardware.
Energy efficient and long
lasting suitable home parties.
$
Active Noise Cancellation
Headphones with Built-in USB
Rechargeable Batteries
DMX Relay Control Kit
These IR emitter kits act like a hub,
enabling you to interface all IR
remote controlled devices
together and control them from
a single sensor point.
2-Way AR-1812 WAS $79.95
NOW $59.95 SAVE $20
6-Way AR-1814 WAS $99.00
NOW $79.00 SAVE $20
iPhone® not included
• Test software and DMX Light
Player software included
• 512 DMX channels with 256
levels each
• 3 pin XLR-DMX output connector
• Size: 106(L) x 100(W) x 44(H)mm
KV-3610 Limited stock. Not available online
IR Extender Kit 2X
3W CREE® LED Mini
Spotlight
6
3995
$
HDMI 3-Port Switch
• Headphone jack for
private practice
• Built-in E-string tuner
• 2W Mono speaker
• Requires 1 x 9V battery for
up to 8 hours play
• Size: 180(L) x 90(W) x 155(H)mm
CS-2553
White LED SL-3470 $34.95
Blue LED SL-3471 $34.95
14900
$
2 Input HDMI Switcher
$
Portable Practice
Amp
Enjoy crystal clear digital radio broadcasts, or listen to your MP3s directly from your SD
card or USB memory stick. Charge your iPod® or iPhone® while listening to your daily
podcasts, or load your CD and set your alarm so you'll awake the next
morning to the sounds of your favourite playlist.
NEW
3995
$
• 512 unique addresses,
selectable with DIP switch
• Status LED for power and error detection
• Size: 150(L) x 60(W) x 45(H)mm
$
KV-3614
Limited stock. Not Available online
4995
All savings based on Original RRP. Limited stock on sale items.
Prices valid until 23/08/2012.
POWER CONTROL DEALS & BARGAINS
Mains Power Monitor with
USB interface
60 Minute Fast Charger
with USB Port
Monitors the energy consumption of
an entire home to determine how
much electricity the appliances use.
Displays power, cost, CO2 and
temperature.
Recharge up to 4 x AA or AAA
Ni-MH batteries fast. Delta -V
controlled unit prevents over
charging and the auto cut-off
safety timer adds protection.
• 433MHz wireless
transmission up to 40m
• Includes 2 x D batteries
for transmitter
• Display unit uses
mains power or
requires
3 x AAA batteries
• Max sensor current: 100A
MS-6165 Was $119.00
• 4 individual channels
with LED indicators
• Charge current 2200mA
for AA, 850mA for AAA
• Supplied with 240VAC
adaptor & 12VDC adaptor
• Size: 114(L) x 75(W)
x 30(D)mm
MB-3561
9900
$
Batteries not included
NEW
3995
$
SAVE $20
Deluxe Mains Power
Meter with CO2 Measurement
This meter tells you the cost of electricity consumption of an
appliance plugged into it and the amount of power used in
kilowatt hours, as well as how
many cumulative kg of CO2 the
appliance is putting into the
atmosphere.
• Extra large LCD for
easy reading
• Size: 120(L) x
58(W) x 40(H)mm
MS-6118
Fluorescent Tube Adaptors T5-T8
2995
$
Buy 2 for
$50 SAVE
$9.90
Smart Powerboard with
Energy Meter
Easy to use and set up! Plug the main device e.g. a
TV into the "smart" outlet, switch it off and all other
plugged in devices will also turn off. The energy
meter shows consumption in watts, cents per hour or
CO2 kg per hour.
5995
• Surge protection, overload,
$
spike and noise filtering
• Cord length 900mm
• Size: 385(L) x 60(W) x 30(D)mm
MS-6152
Mains Standby Power Saver
with IR Receiver
This energy saving device eliminates the
standby power consumed by most
modern appliances. Simply program
the power saver with the standby
level for your system and it will shut
the power off whenever the set level
is reached. Program any IR remote
control to turn the power
saver on again for simple
and effective operation.
• Size: 128(H) x 65(W)
x 40(D)mm
MS-6146 Was $29.95
Wireless 3 Outlet
Mains Controller
Spare Mains Outlet with Light
MS-6143 $17.95
4 Channel Single
Blade RC Helicopter
This 4 channel helicopter allows a wider range of
movement and has a built in gyroscope for stability.
Equipped with 2.4GHz remote control for more
responsive control. Recharged through the USB
charger included.
• Built in
Gyroscope
• Single blade
• 3.7V 150mAh
Li-Po battery
included
• 55 minutes recharge for
about 7-10 min flight time
• Remote requires 6 x AA batteries
• Size: 240(L)mm
• Suitable for ages 14+
$
GT-3430
6995
2495
$
SL-2748 $19.95
NEW
NOTE: Not suitable in T8 fittings
with electronic ballasts.
From
1795
$
Recreational Solar Panel Package
80W Standard Recreational Solar Package
Clean renewable energy wherever you go. Solar-convert
your 4WD or caravan to generate sufficient power to
operate several appliances - including your laptop, portable
lighting, CB radio and 12-24V camping electricals. Just add
a battery for your own self-sustained solar powered setup.
30000
$
DIY Package
& SAVE $$$
SAVE $5
Ask our staff for more SOLAR PACKAGES to suit your needs
Mains Timer with LCD
Control lighting or powered appliances
with this programmable timer.
• 8 on/off programmes across
16 combinations of days or
blocks of days
• Internal battery
$
backup
• Rated up to 10A
MS-6110
2495
3495
$
SAVE $10
Mains Outlet/Night-Light with Remote
24 Hour Mechanical
Mains Timer
Control any 240V mains appliance rated
up to 10A. Simply rotate the dial to the
time you want, then switch it on. Suits
any 240V 10A GPO.
MS-6145 $24.95
Digital Mains Timer
Switch Modules
Ideal for automating your heating
& lighting or practically any other
switching application that requires
multiple unattended switching
cycles. The timer has eight
$
95
on/off settings that can be
ea
programmed to function on
SAVE $10
any day, or combinations of
days across the week.
39
12VDC Supply, Switches 16A<at>240VAC SPDT
AA-0361 WAS $49.95 NOW $39.95 SAVE $10
240VAC Supply, Switches 30A <at> 240VAC SPST
AA-0362 WAS $49.95 NOW $39.95 SAVE $10
Better, More Technical
Replaces 40W Tubes with 28W T5 Tubes
• Package includes: monocrystalline
solar panel, charge controller, 2 x
male and female PV connectors
ZM-9300
Simply plug in any mains appliance rated up to
10A and use the remote to turn each one on or off
individually, or control all of them together. One of
the outlets has an LED night light that's also
operated with the remote.
• 433MHz
• Remote
battery
included
• Remote
size: 125(W)
x 45(H) x
17(D)mm
MS-6142 Was $44.95
Easily convert traditional T8 fluorescent lighting to
more energy efficient T5 series tubes using these
tube adaptor sets. T5 tubes
output the same light
level as standard T8
tubes while consuming
up to 40% less power.
Easy installation.
Light
Replaces 20W Tubes with 14W T5 Tubes
Energy
SL-2746 $17.95
Saving
• Size: 120(H) x
76(W) x 50(D)mm
MS-6112
995
$
Voltage Regulator Kit
Refer: Silicon Chip Magazine May 2007
This handy voltage regulator can
provide up to 1,000mA at any
voltage from 1.3 to 22VDC.
Ideal for experimental projects
or as a mini bench power supply.
Kit supplied with PCB and all
electronic components.
• PCB: 38 x 35mm
KC-5446
1695
$
www.jaycar.com.au
7
SECURITY DEALS & BARGAINS
2.4GHz DIGITAL
Wireless Mini
DVR Kits
Flush Mount Reed Switch Set
for Timber Frames
RECEIVE 50%
OFF ON SPARE
CAMERAS* WHEN
PURCHASED WITH
EITHER CAMERA/
RECEIVER KIT
Just drill a recess in your door or window and the
magnet flush mounts to be "invisible". The reed
These mini DVR systems operate
switch segment is similarly mounted into the door
on the 2.4GHz DIGITAL band for stable,
frame or window frame &
interference-free transmissions. Two
wired into your
models available, both include one
system.
colour outdoor day/night camera
QC-3630 shown
with motion sensor, a ball &
Tapered version to suit Timber Frames
NEW
From
socket mounting bracket, and
LA-5075 $4.95
$
95
utilise channel hopping to
Toothed version to suit Metal Frames
prevent inference. Both
LA-5076 $5.95
have easy to navigate
system settings,
2.4GHz CCTV Wireless
manual recording,
AV Sender
schedule recording
Wirelessly transmit high resolution
or record with
D1 images (720 x 576) to a digital
motion detection. Both
video recorder up to 300m away.
use SD cards (not included) to store video and
Each unit features mounting
playback is via SD card to a PC. Both systems are
holes for secure attachment,
expandable for up to four cameras.
an antenna for each unit and
2.4GHz DIGITAL Wireless Receiver with Camera
NEW
a compact 9VDC power supply.
QC-3630 WAS $199.00 NOW $179.00 SAVE $20.00
$
00
• FHSS mode up to 80 channels
2.4GHz DIGITAL Wireless Display / Receiver
•
9VDC
power
supply
included
with Camera and Integrated 7" LCD
• Size (excluding antenna): 163(L) x 97(W) x 48(H)mm
QC-3632 WAS $279.00 NOW $259.00 SAVE $20.00
QC-3201
Additional cameras to suit:
10 Zone Alarm Kits
From
Mains powered QC-3634 $139.00
$
00
Fully configurable and programmable. Includes a
Solar powered QC-3633 $189.00
central controller and the sensors you need to get a
Limited stock. Not available online
SAVE $20
basic system up and
running. Up to four
remote
keypads can
3.5" LCD Camera Kit
be installed at
Connect power and
up to 100m range
install the camera
and each can be
where needed. The
named for easy identification.
3.5" TFT LCD gives
• 10 programmable zones
real-time video
$
00
• 4 access levels
monitoring and the
• Walk test mode
SAVE $70
microphone in the
• Events memory in keypads
camera provides
• Programmable timers for entry, exit and alarm
audio either through
duration
the speaker in the display unit or via
• Kit includes: control panel, LED controller, PIR
headphone outlet. 20m power/video
sensors, reed switch, bellbox, 50m 6 core cable
cable and mains plugpack included.
and 12V 1.2Ah backup battery
• IR illuminator
LA-5560 Was $299.00
• CMOS sensor
• Size: 130(W) x 80(H) x 22(D)mm
Spare controllers and sensors also available:
QC-8007 Was $149.00
LED Remote Controller LA-5561 $49.95
$
00
Spare camera also available:
LCD Remote Controller LA-5563 $69.95
QC-8009 $69.00
SAVE $30
PIR Sensor
LA-5564 $29.95
4
199
179
229
119
Wireless Intercom
Doorphone 2.4GHz
A compact doorphone using
2.4GHz DIGITAL
transmission for crystal
clear interference-free
reception up to 100m
range. Never miss
anyone at the door with
the portable receiver which can be
taken anywhere around the house
or even the garden. 240V mains
charger included.
AM-4332
NEW
7995
$
Digital Keypad with RFID
Access Control
A single door multifunction standalone
access controller or a Wiegand output
keypad/card reader suitable for an
area requiring stricter access control
such as a laboratory, warehouse,
bank, or prison. Housed in a sturdy
zinc alloy casing and can support up
to 2000 users. Full installation and
wiring instructions in manual.
• 12VDC
• Waterproof
• LED indicator (green/yellow/red)
• Wiegand 26 input for connection
of external reader
LA-5353
NEW
9900
$
Professional 32 Channel Hybrid DVR
Capable of simultaneously
recording video from
32 cameras, this
DVR will record
16 analogue
camera inputs and
an additional 16 IP camera inputs enabling you to handle
all your surveillance needs in a single system. Powered by
a dual core CPU with sufficient power to record all 32
channels at D1 resolution (704 x 576) at 400 frames per
second and multiplex the channels to a single video output.
Live video and playback can be displayed through the HDMI,
composite, or VGA outputs and accessed through a network
connection using a web browser or an iPhone®, iPad®, or
Smartphone app*. Supplied with a 1TB
SATA HDD. See website for
NEW
specifications.
• Size: 460(D) x 440(W) x 89(H)mm
QV-8124
1499
$
YOUR LOCAL JAYCAR STORE - Free Call Orders: 1800 022 888
• AUSTRALIAN CAPITAL TERRITORY
Belconnen
Fyshwick
Ph (02) 6253 5700
Ph (02) 6239 1801
• NEW SOUTH WALES
Albury
Alexandria
Bankstown
Blacktown
Bondi Junction
Brookvale
Campbelltown
Castle Hill
Coffs Harbour
Croydon
Erina
Gore Hill
Hornsby
Liverpool
Maitland
Ph (02) 6021 6788
Ph (02) 9699 4699
Ph (02) 9709 2822
Ph (02) 9678 9669
Ph (02) 9369 3899
Ph (02) 9905 4130
Ph (02) 4620 7155
Ph (02) 9634 4470
Ph (02) 6651 5238
Ph (02) 9799 0402
Ph (02) 4365 3433
Ph (02) 9439 4799
Ph (02) 9476 6221
Ph (02) 9821 3100
Ph (02) 4934 4911
Newcastle
Penrith
Port Macquarie
Rydalmere
Sydney City
Taren Point
Tuggerah
Tweed Heads
Wagga Wagga
Wollongong
Ph (02) 4965 3799
Ph (02) 4721 8337
Ph (02) 6581 4476
Ph (02) 8832 3120
Ph (02) 9267 1614
Ph (02) 9531 7033
Ph (02) 4353 5016
Ph (07) 5524 6566
Ph (02) 6931 9333
Ph (02) 4226 7089
• NORTHERN TERRITORY
Darwin
Ph (08) 8948 4043
• QUEENSLAND
Aspley
Caboolture
Cairns
Capalaba
Ipswich
Labrador
Arrival dates of new products in this flyer were confirmed
at the time of print. Occasionally these dates change
unexpectedly. Please ring your local store to check stock
details. Prices valid from 24th July to 23rd August 2012.
Ph (07) 3863 0099
Ph (07) 5432 3152
Ph (07) 4041 6747
Ph (07) 3245 2014
Ph (07) 3282 5800
Ph (07) 5537 4295
HEAD OFFICE
Mackay
Maroochydore
Mermaid Beach
Nth Rockhampton
Townsville
Underwood
Woolloongabba
Ph (07) 4953 0611
Ph (07) 5479 3511
Ph (07) 5526 6722
Ph (07) 4926 4155
Ph (07) 4772 5022
Ph (07) 3841 4888
Ph (07) 3393 0777
• SOUTH AUSTRALIA
Adelaide
Clovelly Park
Elizabeth NEW
Gepps Cross
Reynella
• TASMANIA
Hobart
Launceston
• VICTORIA
Cheltenham
Coburg
320 Victoria Road, Rydalmere NSW 2116
Ph: (02) 8832 3100 Fax: (02) 8832 3169
Ph (08) 8231 7355
Ph (08) 8276 6901
Ph (08) 8255 6999
Ph (08) 8262 3200
Ph (08) 8387 3847
Ph (03) 6272 9955
Ph (03) 6334 2777
Ph (03) 9585 5011
Ph (03) 9384 1811
ONLINE ORDERS
FernTree Gully
Frankston
Geelong
Hallam
Kew East
Melbourne
Ringwood
Shepparton
Springvale
Sunshine
Thomastown
Werribee
Ph (03) 9758 0141
Ph (03) 9781 4100
Ph (03) 5221 5800
Ph (03) 9796 4577
Ph (03) 9859 6188
Ph (03) 9663 2030
Ph (03) 9870 9053
Ph (03) 5822 4037
Ph (03) 9547 1022
Ph (03) 9310 8066
Ph (03) 9465 3333
Ph (03) 9741 8951
• WESTERN AUSTRALIA
Joondalup
Maddington
Mandurah
Midland
Northbridge
Rockingham
Website: www.jaycar.com.au
Email: techstore<at>jaycar.com.au
Ph (08) 9301 0916
Ph (08) 9493 4300
Ph (08) 9586 3827
Ph (08) 9250 8200
Ph (08) 9328 8252
Ph (08) 9592 8000
PRODUCT SHOWCASE
New 11-input, 5-output Mixer from Altronics
Altronics Distributors have added
to their already extensive range of
Redback professional audio gear with
this new comprehensively-equipped
audio mixer, ideally suited to DJ and
other pro audio work. A program cue
selector allows a DJ to cue upcoming
music tracks from any channel.
It can accept up to 11 input sources
with a versatile selection: mono
channels one and four accept either
mic (6.35mm, 1.5mV) or line (RCA,
150mV) inputs; channels two and
three are switchable stereo line or
phono (3mV) via RCA sockets. Channel five is stereo line only, again via
RCA sockets.
Somewhat surprisingly there is a
lack XLR microphone sockets, apart
from the DJs mic on the top panel
(most “pro” mics use XLR connectors).
In keeping with the “DJ” use, the
two phono inputs are for two magnetic
cartridge turntable inputs – a significant proportion of DJs still prefer vinyl
over CDs.
Each channel has a 3-band graphic
equaliser and individual fader volume
controls, plus crossfader assignment
across all channels, which allows
for fading from one music source to
another without interruption.
The five outputs include master,
zone and record outputs, all stereo,
via RCA sockets, and two master
(mono)balanced XLRs. There’s also a
DJ headphone socket.
All this means it’s not a small pack-
age: at 428 x 101(h) x 188 (d) and a
4kg weight, it’s portable without being tiny.
The box includes a 9V AC/1500mA
plugpack power supply and a quite
comprehensive instruction manual
with detailed setup diagrams and
explanations.
All in all, it’s a most comprehensive
mixer and one that will be welcomed
by professional and semi-professional
audio operators.
It has a recommended retail price
of $299 (Cat A 2554) and is available
from all Altronics stores, resellers and
via their website.
Contact:
Altronic Distributors Pty Ltd
PO Box 8350, Perth Busn Centre, WA 6849
Tel: 1300 780 999 Fax: 1300 790 999
Website: www.altronics.com.au
Electronex returns to Sydney
Electronex – the Electronics Design and
Assembly Expo returns to Technology Park
in Sydney from the 12 -13 September. The
exhibition will be almost 50% larger than
the inaugural expo in 2010.
The exhibition is open to engineers,
production and purchasing staff involved
in electronics design, assembly, manufacture and repair.
The SMCBA Conference will be held
concurrently with the expo and will feature
several international experts and cover a
wide range of topics critical to successful
CALL IN AND SAY HELLO TO
siliconchip.com.au
design, assembly and test of electronics
products and systems.
International presenters will include
Gary Ferrari, Director of Technical Support for FTG Circuits, Dave Hillman who is
with the Advanced Operations Engineering
Department of Rockwell Collins and Craig
Hillman, Director of DfR Solutions.
For further information and conference
or visitor registration details please visit the
show website www.electronex.com.au
SILICON CHIP ON STAND C33
2-18 contact goldplated PCB connectors
The Switchcraft EN3 right-angle
PCB mount plug and socket from
Clarke & Severn Electronics has applications for any sealed data transmission, military or industrial GPS
location devices, environmental monitoring, transportation, medical data
carts, marine and general industrial
electronic applications.
Utilising an integral O-Ring/gasket,
EN3 right-angle panel connectors
are available in 2-18 pins/sockets in
the same housing size with bayonet
locking.
The right-angle PCB mount contacts
meets enclosure rating IP66/IP68 and
NEMA 250 when mated or covered.
Narrow or wide versions are available and gold-plated contacts ensure
reliable and uninterrupted connectivity.
SC
Contact:
Clarke & Severn Electronics
Unit 4/8A Kookaburra Rd, Hornsby NSW 2077
Tel: (02) 9482 1944 Fax: (02) 9482 1309
Website: www.clarke.com.au
August 2012 57
SERVICEMAN'S LOG
Watchmaking is not really my forte
Watchmaking is not exactly my forte but I’ll
take on just about anything these days to try
to make a dollar. Sometimes my efforts are
successful and sometimes they aren’t but it
doesn’t hurt to at least try.
I’ve said it before and I’ll say it again;
in the current economic climate here
in Christchurch, I’m prepared to have
a look at anything that needs fixing, as
long as the client is prepared to pay for
my time. The other day, for example, I
turned my hand to wristwatch repair
although I have to say right up front
that this type of work is not really my
bag. However, someone asked if I could
fix such things and since I am always a
soft touch, I said I’d have a look.
Of course, if it had been a wind-up
watch, I wouldn’t have even bothered
opening the back. Those types of
watches are strictly for the professionals. And with new watches now selling
for peanuts, it’s seldom worth repairing run-of-the-mill watches anyway.
In this case, the watch apparently
had sentimental value and after agreeing on a reasonable “dollar-cap”, I got
stuck into it. The problem with this
8-year-old ladies Casio quartz timepiece was that the hands had stopped
58 Silicon Chip
moving. Usually, when something like
that happens, the battery has gone flat
and replacing it fixes the problem.
However, when I pressed the illumination button on the side of the watch,
the LED backlight told me that there
was plenty of juice left in the battery.
The first thing to really become apparent when I started working on the
watch is that when it came to handling
the tiny screws and other micro-fittings, I suddenly felt as if I had fingers
of butter and fists of ham – and that’s
despite being able to handle surfacemount parts on PCBs. I also discovered
that a decent head-mounted magnifier
is essential for an aging serviceman to
be able to even see what is going on.
Fortunately, I have a set which I modified to use high-intensity LEDs instead
of the old incandescent globes it used
to have. Nothing beats good lighting
when doing such fine work.
However, while my illuminated
magnifier was a great start, my other
tools fell short. All the screwdrivers,
pliers and tweezers I normally work
with were suddenly way too big and
totally impractical for watch repair
work. Even the smallest flat screwdriver in my set of so-called “jeweller’s screwdrivers” was too fat for this
watch’s miniature screws.
However, I also have some ultrasmall screwdrivers and tweezers,
along with some other micro-tools,
stored away from my aircraft engineering days. They’ve been sitting in
a drawer, unused since my time in the
instrument repair shop.
As it turned out, I didn’t really need
them because as soon as the watch’s
back was removed, the problem was
obvious; a pale green “fuzz” coated
the entire insides. This “fuzz” was
Dave Thompson*
Items Covered This Month
•
•
•
Watchmaking is not my forte
Buzzing recording studio
Of mice & Triacs on a chook
farm
• The spider & the Hereaus
photo-polymiser machine
• Faulty LG dishwasher
• Soniq E19Z10A 48cm TV
*Dave Thompson, runs PC Anytime
in Christchurch, NZ.
mould, caused by moisture getting
in, and it had wreaked havoc with the
sensitive electronics and clockwork
mechanisms.
It didn’t take a crime-scene investigator to figure out why this had happened. A sorry-looking, chewed-up
O-ring lay among the mould. This
thin rubber seal is usually placed in
a small notch cut around the outer
edge of the housing at the back of the
watch. When the back-plate is clipped
in place, it slightly compresses the
O-ring, sealing the interior from the
elements and hopefully preventing
moisture getting in.
In this case, the O-ring hadn’t been
seated properly and at some stage in
the past, had been crushed and partially severed when the back had been
pressed on following a recent battery
change. As a result, there was virtually
no seal at all.
At this point I knew it would be
highly unlikely I could repair this
watch, though I persevered out of
interest. First, I removed three tiny
screws that were holding a thin springplate to the rest of the movement. This
was then eased clear of the movement
and I could then actually see light
reflecting off the moisture that had
gathered underneath it.
The PCB, which occupied about a
third of the room inside the case, was
semi-circular in shape and contained
several surface-mounted resistors and
capacitors, along with other unidensiliconchip.com.au
The buzzing recording studio
For most musicians, a recording studio is a hallowed
place. I’ll never forget the first time I visited a real
recording studio; I was 18 at the time and the sight of
a 60-channel mixing console and racks of high-end
audio-processing gear was enough to kindle a life-long
love of such places.
So imagine my excitement when a new client
wanted me to head over to his recording studio to show
him a foot controller that I’d made. Like me, he’d been
looking for a means of controlling his computerised
Digital Audio Workstation (DAW) and through a mutual friend he’d heard I had recently made a wireless
USB footswitch. I duly took it with me and as soon
as he clapped eyes on it, he wanted one.
In the old days, analog multi-track recorders had
remote switching capability, meaning transport
siliconchip.com.au
G r e a t V a l u e i n Te s t & M e a s u r e m e n t
tifiable components. At one end, a tiny cylindrical
crystal nestled into the movement’s plastic moulding
while at the other end sat a coil of ultra-fine wire. I
assumed that both were part of the oscillator timing
circuit.
Undoing two more tiny screws released the circuit
board which I then carefully removed using tweezers.
Like most modern circuit boards, it had been coated
in a clear, hard lacquer but every exposed soldered
or metallic area had still been significantly corroded.
When confronted with circuit boards like this, I
usually break out my fibreglass PCB cleaning pen.
This invaluable piece of workshop kit is like a widetipped marker pen but instead of having a solid felt
ink dispenser, it has stiff, brush-like bristles made of
strands of fibreglass. An adjustment wheel at the top
end of the pen winds the bristles in or out of the barrel, to give a gentler or harsher action.
It’s an excellent cleaning medium for stripping the
likes of flux or even burnt fibreglass from a circuit
board, or the aforementioned lacquer or corrosion.
Anyway, I got stuck in but after cleaning the board, it
was obvious that the prognosis was terminal. Even if I
had the eyes of an eagle and a pin-sized soldering iron,
I seriously doubted whether I could repair the tracks.
The only realistic option was replacement. I had
a good look on Google, Casio’s web site and the sites
of various Chinese manufacturers to see if a spare
movement was available. It was but as is always the
way with spare parts, a new watch would cost far less
than the spares, delivery and labour, no matter how
cheap my time goes for these days.
In the end, I put it all back together and returned
the watch to its owner, who now has it sitting in a
drawer, not wanting to throw it away. I didn’t have
the heart to charge because I hadn’t done anything
other than confirm what I already suspected before I
started the repair.
The moral of this story is that if the guy who replaced the battery a few months before had done his
job properly, the watch would still be going. And it
would have lasted many years longer, all for the sake
of a 5-cent O-ring. Next time you get your watch battery changed, ask the salesperson to check the seal;
it’s well worth paying a bit extra to have it replaced.
CAN bus analysis now also available
in the oscilloscope entry level class
200 MHz 2[4] Channel Digital
Oscilloscope HMO2022 [HMO2024]
2GSa/s Real Time, Low Noise Flash A/D Converter
(Reference Class)
2MPts Memory, Memory Zoom up to 50,000:1
MSO (Mixed Signal Opt. HO3508) with 8 Logic
Channels
Serial Bus Trigger and Hardware accelerated Decode
incl. List View, I2C, SPI, UART/RS-232, CAN, LIN
(optional)
Automatic Search for User defined Events
Pass/Fail Test based on Masks
Vertical Sensitivity 1mV/div., Offset Control
±0.2...±20V
12div. x-Axis Display Range, 20div. y-Axis Display
Range (VirtualScreen)
Trigger Modes: Slope, Video, Pulsewidth, Logic,
Delayed, Event
Rohde & Schwarz (Australia) Pty Ltd
Unit 2, 75 Epping Road, North Ryde
NSW 2113
www.rohde-schwarz.com.au
sales.australia<at>rohde-schwarz.com
August 2012 59
Serr v ice
Se
ceman’s
man’s Log – continued
functions such as Stop, Play, Pause,
Rewind, Forward and Record could
be controlled either by switches
mounted on the mixing console or
by foot-switches placed underneath
the workstation. Foot controllers are
the obvious choice because they free
up the hands and greatly improve
workflow.
Of course, most modern studios
do everything on computer these
days and have done away with the
old-style analog reel-to-reel recorders
altogether. However, my new client’s
studio is set up to do both analog and
digital 24-track recording, with the
older systems maintained for those
artists who prefer more retro sounds.
In this case though, something
wasn’t quite right because while I
was demonstrating my footswitch to
the client, I encountered something I
consider sacrilegious in a recording
studio – noise.
When the guy cranked up his monitor system, all I heard was an alarming
buzz. Even when the song he’d loaded
into his recording software to test the
foot-controller started playing, there
was an insidious buzz beneath the
otherwise excellent audio fidelity.
Usually, engineers struggle to ensure
that studio amplifier and speaker systems are as quiet as humanly possible.
Having a buzz in the system is like a
supermodel with missing front teeth;
it just isn’t right. I mentioned the noise
to my friend and he said it was once as
quiet as a mouse but had gotten worse
in recent times but he didn’t have the
knowledge to track down the source.
And he asked if I would like to have
a go at fixing it.
Well, that’s like asking a kid if he
wants some lollies! I said I’d love to
give it a shot.
I returned a few days later with my
tools, a multimeter and my trusty signal injector. Anyone who has seen a
recording studio of any size will know
the cabling involved can be considerable. This studio was initially set up
with an analog 24-track machine and
later modified to include 24-track
digital capability, with dozens of
expensive and complicated-looking
rack-mounted analog-to-digital converters, all with leads running in and
out to a seriously large mixing console.
This all added up to many, many
audio cables running in and out of the
desk, effects chains, monitor amplifi-
Servicing Stories Wanted
Do you have any good servicing stories that you would like to share in The Serviceman column in SILICON CHIP? If so, why not send those stories in to us? In doesn’t
matter what the story is about as long as it’s in some way related to the electronics
or electrical industries, to computers or even to car electronics.
We pay for all contributions published but please note that your material must
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Please be sure to include your full name and address details.
60 Silicon Chip
ers and speakers. In other words, the
back-end looked like a rat’s nest and I
was beginning to regret being so hasty
to offer to help out. Like many complicated systems, this had originally been
nice and tidy but had then been added
to piecemeal by various technicians
and engineers, most of whom were
no longer around. As a result, nobody
now has any idea who did what and
what goes where.
My first step was to try to isolate
this buzz to one particular area. Was
it originating in the mixing console?
Or was it coming from somewhere in
the monitor system? I unplugged the
outputs (sends) from the mixing desk
to the monitor amplifiers and plugged
in a pair of headphones instead. The
buzz was still there. That meant I could
rule out the monitor system’s amplifiers, leads and speakers.
Now all I had to do was try to find
where it was being introduced into
the desk. One way I could do this was
remove every input lead while wearing
the phones and see if that cured the
buzz, so that’s what I did. However,
there was no change, even after every
input had been isolated.
That meant bad news; the buzz was
in the console so the next step was to
isolate where in the desk the noise was
coming from. Could it be something
nearby superimposing mains hum into
the system?
Most mixing consoles have rows of
lights along the top, giving engineers
the ability to kill the house lights and
work in the mood-inspiring glow of the
desk lamps. This console had a dozen
small incandescent lamps mounted in
gooseneck holders spread out over the
length of the desk and these were on
all the time, being powered on with the
main desk power. There were six pairs
of lamps controlled by six switches,
which I turned off one by one. And
when I switched off one pair, the buzz
disappeared. Ahhah!
While my client ran the lamps flat
out all the time, they could actually
be dimmed by a knob on the desk. As
a result, I suspected that this dimmer
was faulty and was causing the noise.
However, because this was all built
into the console, I wasn’t about to dive
in and mess with it.
My client wasn’t too bothered,
claiming it was an old desk which was
due for replacement soon anyway. In
the meantime, he’d just stretch the
lamps from either side to light the area
siliconchip.com.au
Of Mice & Triacs On A Chook Farm
Servicing in rural areas can certainly throw up some interesting
problems. M. G. of Christchurch, NZ
has an interesting story about mice
and Triacs . . .
Some years ago I received a call
from a rural poultry farmer whose
“laying house” lighting controller
had failed. These controllers are
designed to simulate sunrise and
sunset and by cribbing a few hours
each day, an extra day could effectively be added to the week (and
thus make the chooks lay more
eggs).
The fault, it turned out, was that
the Triac had gone open-circuit (or
maybe its gate had failed). However,
because this part was buried deeply
inside the works, it meant that the
unit had to be taken back to the
workshop to be repaired.
Once I had extracted the dead
Triac and fitted a new higher-rated
device, everything worked normally
once more and so I returned to the
farm and reinstalled the controller.
There was an over-ride switch on the
lighting circuit and this allowed the
lights themselves to also be tested.
Not unexpectedly, the owner
wanted to know what had caused
the fault and as the unit had been
running for about 10 years, I suggested the most probable cause was
age related.
A week later, I received another
call from the farmer, advising that
the controller had just failed again.
This time, however, the lights were
staying fully on so obviously the
replacement Triac had shorted out.
Once again, I went out to the farm,
collected the controller, returned it
the pair we turned off had covered. It
was a simple fix and the studio monitor system is now as quiet as an empty
church.
An itsy-bitsy spider
Spiders and other creepy-crawlies
can cause all sorts of faults in electronic equipment. Here’s one such
story from I. R. of Alice Springs, NT . . .
I have been involved in the biomedical engineering field for about 25 years
now. This is a diverse technical field
supporting the medical profession
siliconchip.com.au
to the workshop, stripped it down
and carried out the required repairs.
I then returned to the farm and
reinstalled it. As before, the lights
tested out OK and the insulation
resistance was perfectly normal, so I
simply put the Triac failure down to
“infant mortality”. And so, expecting that that would be the end of the
matter, I returned to workshop with
the profit margin on this job now
looking decidedly lean.
What is it that they say about
things happening in threes? Well,
just 10 days later there was yet another call from a now somewhat irate
farmer. The controller had failed yet
again and as on the last occasion, the
lights were fully on. And so once
more, it was out to the farm to collect
the controller, return to base, repair
the unit, and then return to the farm
to reinstall it.
While driving to and from the
farm, I began to ponder what might
be causing this problem. The replacement Triac was a 600V 16A
device driving a circuit drawing
slightly under 10A, whereas the
original Triac was rated at just 400V
12A and it had lasted 10 years. In addition, the controller was a dimming
type, so there was no inrush current
as usually occurs with incandescent
lamps. What’s more, the insulation
resistance was good and there were
no shorted lamps.
So while I was installing the
controller, I asked the farmer if he
had noticed any unusual power
fluctuations around the times of
the failures. This area is notorious
for power outages, as periodically
Canada Geese and/or Black Swans
and involves electronics, pneumatics,
hydraulics, RF, lasers, robotics, nuclear medicine and various computer
applications. So it’s an interesting
career to be in.
Working in a hospital in a remote
outback town means that you get to be
involved in all sorts of jobs, rather than
just specialising in one specific area.
For example, one day I got a call from
the dental lab concerning an on-going
intermittent fault in a Hereaus photopolymeriser machine that’s used to
cure dental resins in mouth-guards
have a bad habit of flying into the
high-tension cables with fatal effect.
His answer was that nothing unusual had occurred but then, after a
long pause, he said that over the past
few weeks there had been quite a
number of dead mice appearing on
the floor in the No.3 shed. He went
on to explain that they had not been
using the No.3 shed for some time
but had subsequently received a bigger shipment of hens than usual, so
they had reinstated it.
Suspecting a clue, I asked him
where in the shed the mice were
appearing and he said just inside the
entrance way. Ahhah! – the penny
tumbled! I grabbed my steps and
torch from the van and went down to
the No.3 shed for a good look around.
The lighting cable path ran along
the lintel at the top of the doorway
and the cable used was the older
TPS type. This is the type that rodents love to gnaw and in this case,
they had really gone to town on the
insulation, to the extent that the top
half of all three conductors was completely exposed for the full width of
the door lintel!
At the centre of the lintel there
was a support that narrowed the
path. As a result, any mouse traversing the lintel had to run on the
exposed wires. It was sort of like
Russian Roulette if the lights were
on. Some made it, some didn’t and
eventually those who didn’t make it
blew the Triac.
The cable was replaced and a
cover placed over it to prevent
further rodent problems. After that,
there were no more failures and the
customer was happy.
and dentures. The fault was that,
over the last few weeks, the unit had
sometimes randomly stopped working
with a lamp failure message and this
problem had now become permanent.
This machine employs a high intensity xenon flash lamp which is very
expensive to replace. When the fault
originally started occurring, I thought
that the problem was likely the lamp
so one was placed on order. Because
it’s such a specialised lamp, it had to
come from Germany which meant a
delay in delivery.
August 2012 61
Serr v ice
Se
ceman’s
man’s Log – continued
The problem was that, now that the
machine had stopped completely, the
lab technicians were forced to use an
older curing unit which takes much
longer than the Hereaus machine. This
was a major inconvenience but eventually the new lamp arrived and was
duly installed. Unfortunately, much
to my dismay and embarrassment, the
machine still refused to function – all
this with the lab technicians looking
on.
In short, there was no change in
the machine’s behaviour. The lamp
would only fire briefly several times
before the machine shut down with the
same lamp failure message. After some
poking around, I eventually decided
to cart the heavy lump of expensive
“junk” back to my workbench for a
further look before contacting the support company.
By now, the pressure was on to get
this machine going again. So in view
of the lengthy downtime that would
result if the unit had to be sent back
to Germany, I decided to give the unit
a detailed check-out for any obvious
faults. Unfortunately, we didn’t have
any service documentation, so I was
flying blind.
Initially, I figured that because the
unit was trying to run on start-up (ie,
with the lamp briefly firing), this meant
that both the driver circuitry and lamp
were OK. That in turn meant that the
fault had to be with the monitoring
circuitry.
As a result, I removed the lamp and
its reflector to see if I could spot the
monitoring set-up. When I did this, I
immediately noticed a black tube with
a sensor at one end. This sensor would
send a signal to the processor to give
the status of the lamp so I had a closer
look at the lamp side of the tube and
noticed some sort of white membrane
covering the aperture.
I used a dental probe to carefully
examine the membrane and then realised that it was a spider web! And
when I removed the thick web cover,
a very agitated spider raced out like a
goanna with a tin can tied to his tail
and disappeared into the mess on my
workbench, never to be seen again!
Further probing removed the spider’s egg sack and when I was satisfied
that the sensor chamber was completely cleared, I refitted the lamp and
tested the unit which now worked
normally – much to my relief.
I figured that when the fault was
originally intermittent, the spider
had simply taken up residence in the
case and when things got too hot, it
hauled its hairy butt up into the sensor tube, thus causing the machine to
stop after 20 minutes or so. Eventually,
the spider figured that its temporary
refuge would be a good place to make
camp and that’s when the fault became
permanent.
Anyway, the dental technicians
were very happy to have their polymeriser back and as for the spider, well
she’s completely disappeared.
Faulty LG dishwasher
Reader P. M. recently did battle with
a client’s dishwasher but the fault
was quite a simple one. Here’s how
he tells it . . .
I have been repairing electronic
and electrical equipment for many
years and sometimes it’s the simplest
devices which cause the most angst.
At other times, the fault is relatively
straightforward to locate and fix.
I recently inspected an LG dishwasher which was playing up. The
symptom was continued operation
of the drain pump when any wash
program was selected. The dishwasher
would also sometimes display an “OE”
fault code after 10 minutes of the pump
cycling on and off.
Now most of the dishwashers I
have repaired go through a cycle of
emptying first before anything else is
allowed to happen. And in this case,
the owner’s handbook described the
fault as being a kinked or blocked
drain hose.
Dishwashers are generally quite
straightforward and faults can usually
be diagnosed without circuit diagrams
or other information. In this case, the
unit was easy to dismantle to the point
of accessing the pumps and solenoids
underneath. That done, I began by
checking for any obvious corrosion
on the terminals and components,
something that can be a problem with
dishwashers.
In this case, everything appeared
to be OK, and the unit could be run
through its cycle quite safely. After
watching many cycles and manually
pouring water into the machine, the
question became “how does it know
when it’s empty?”
The internet currently holds the answers to all the questions in the world,
so this was now my starting point. A
circuit diagram was easily found and
this showed the wiring for the two
pumps (wash pump and drain pump),
the heater element and various control
circuits. However, I still couldn’t figure
out what “tells” the controller that the
water has all been drained.
Searching for the fault code revealed
hundreds of other people have come
across various error codes, the majority being caused by faulty pumps or
broken wiring in the door. However,
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62 Silicon Chip
siliconchip.com.au
the pump in this machine worked well
and the wiring was all intact.
Eventually, the penny dropped. The
wiring diagram shows a microswitch
connected in series with the heater
element. And so, after exhausting
many possibilities, this microswitch
was removed for a closer look. This
revealed that it was operated by a small
diaphragm and it indicated when water was present in the heater chamber.
If the switch remains open, the
controller assumes that water is still
present in the machine. In this case,
the microswitch was faulty and that
was exactly what was happening.
Replacing it fixed the problem, so it
was an easy fix.
of warranty. It wasn’t worth taking
to a repair shop, as he had paid just
$150 for it.
I soon found that the separate 12V
4A switchmode supply was not working so if this was the only fault, the
repair would be quite simple. A quick
perusal of the Jaycar catalog showed
that they had a 12V 5A unit (Cat. GH1379) for $30, so I decided to use this
as a replacement.
All I would have to do is change the
connector going to the TV.
I duly purchased the power supply
and made some temporary connections to make sure that all was OK
before cutting off the connector. When
I did this, I was surprised to discover
that the TV would only turn on interSoniq TV repair
mittently.
TV sets are now so cheap that most
My first step was to check the outsmaller screen sizes are not worth re- put voltage from the new supply. This
pairing – unless you can get a friend showed that it was dropping to about
to do it for nothing. J. W. of Hilary, 11V. I could hear the relay in the TV
WA recently did a friend a favour trying to turn on but not quite makand found that although the fault was ing it. So was the TV trying to draw
simple, there was a twist to the cure. a large surge of current at switch-on,
Here’s his story . . .
which was proving too much for the
A friend recently asked me to have power supply?
a look
at hisad
Soniq
E19Z10A
48cm
Assure
Connect
11 May
12 14/5/12
10:19TV
AM Page I1decided to risk it and pull the new
with DVD player which was just out power supply apart. MyCinitial
M
Ythought
CM MY CY
siliconchip.com.au
was that there might be a bad connection to the output but this wasn’t the
case. I then noticed that even when
the TV was not connected, the voltage
was regularly dropping to about 11V
and then rising to 12V again.
At that point, the penny dropped –
the power supply did not like running
without a load and the regulation circuitry was constantly trying to pull the
output voltage down. The TV wouldn’t
start when the output was at 11V but
it would start OK if I happened to
switch it on when the power supply
was actually at 12V.
As a result, I experimented with
various resistive loads until I found
the lightest one that would keep the
12V constant without wasting too
much power. Fortunately, the case had
enough room for the 180Ω 2W resistor
I used. And since I already had the
supply apart, I swapped the output
cable over from the defunct supply to
produce a neat repair.
So a simple power supply replacement turned into an hour’s work. Fortunately, when it was all back together,
the TV then worked perfectly and my
friend was happy to get it back for the
SC
costKof the new supply.
CMY
August 2012 63
By NICHOLAS VINEN
Timer for
Fans or Lights
This simple circuit provides a turn-off delay for a 230VAC light or
a fan. It can be used to make a bathroom fan run for a set period
after the switch has been turned off or it can be used with a
pushbutton to turn a light on for a specific time. The timer circuit
consumes no standby power when the load is off.
B
ATHROOMS AND toilets need an
exhaust fan to vent humid air or
odours outside. It’s a good idea to have
the fan running while you shower and
then for a little while afterwards, to
prevent condensation and mould. This
unit makes it easy, by automatically
running the fan for a preset period
after the wall switch has been turned
off and then switching itself off.
And while this timer was designed
specifically with bathroom or toilet
fans in mind, it is equally applicable to
exhaust fans in kitchens where cooking odours need to vented outside. Of
course, cooking also produces large
amounts of water vapour so a fan is
64 Silicon Chip
desirable to avoid condensation on
the walls which can lead to mould.
It has other applications too. For
example, many apartment buildings
have lights in the foyer or stairwell
with pushbuttons to turn them on.
This allows people on any level to
turn the lights on for long enough to
get into or out of the building without
the possibility of them being left on for
long periods. This unit can perform
that task too, when combined with
mains-rated momentary pushbuttons
or spring-loaded switches.
Or do you forget to turn off outdoor
lights after visitors have departed?
This timer will avoid that problem.
You can easily set the time-out from
five seconds to one hour by changing an on-board link and possibly a
capacitor. The whole thing fits in a
standard junction box (Arlec 9071 or
equivalent) for ease of installation.
And as noted above, it has no standby
power so it’s quite “green” (well, the
PCB is anyway).
Commercial units to do these jobs
are available but can be hard to get
and expensive. This SILICON CHIP
design has relatively few parts and it
can handle loads of up to 5A/1250VA.
Improvements
We published a similar mains timer
siliconchip.com.au
SWITCH
A
A
A
Aperm
SWITCH
Asw
A
Aload
FAN
TIMER
Asw
A
FAN
N
N
Aperm
SWITCH
N
LAMP
FAN
FAN
TIMER
Aload
A
FAN
N
N
N
N
N
(a)
(b)
(c)
Fig.1(a) at left shows how a fan (or light) is normally connected, while Fig.1(b) shows how the wiring is changed so the
Timer controls the fan, in conjunction with the switch. Fig.1(c) shows the circuit with the ceiling light in place, where
the light and the fan share a common switch.
for fans in the October 2005 issue.
That design used a PIC16F88 microcontroller and a Triac to control the
fan. While it had some fancy features,
its standby power was several watts
which is something of a drawback
these days. As well, its use of a Triac
makes it incompatible with some compact fluorescent lamps (CFLs).
This new design dispenses with the
need for a micro, so there is no need
for programming. Instead, it is based
on a cheap and commonly available
CMOS oscillator/counter IC. There is
no Triac either, as the load switching
is done by a mains-rated relay.
Connections
The Mains Timer is designed to be
added to an existing fan or light installation with minimal fuss. Fig.1(a)
shows how a typical fan is wired up
(this also applies to lights). The 3-core
mains cable is normally run in the ceiling cavity with the Active line splitting
out to run down to the power switch,
mounted on the architrave or wall
below. The switched Active line then
runs back up into the ceiling to connect to the fan. Neutral and possibly
Earth are permanently connected to it.
Fig.1(b) shows how the Mains Timer
would be connected into the circuit.
As before, Neutral and Earth wires
run straight to the fan. The timer is
connected in-line with the switched
Active, with the wire from the switch
going to its “Asw” terminal and the
wire to the fan coming from its “Aload”
terminal.
Two additional wires, “Aperm”
and “N”, are run back to the Active
and Neutral supply. For the sake of
convenience, the junction of the two
Neutral lines may be made on the
siliconchip.com.au
Mains Timer PCB if desired.
The additional Active line (Aperm)
is necessary to power the fan or light
after the mains switch has been turned
off. The Neutral line is used to power
the timer circuitry without affecting
the voltage delivered to the load.
Finally, Fig.1(c) shows how you can
add an exhaust fan to a room which
only has a light switch, using the one
switch to turn on the both the fan and
the light. When the switch is turned
off, the light goes off immediately but
the fan runs for the preset time before
it too goes off. All you have to do is
run the switched Active line from the
light to the Asw terminal on the timer
and then run the Active, Neutral and
load (fan) wires as shown.
Circuit description
Fig.2 is a simplified diagram of the
S1
(OFF
BOARD)
K
Timer, showing how its power supply
works. This configuration allows it
to have zero standby power. Initially,
the mains switch (S1) is off and so is
D1
D3
A
10M 1W
K
K
D5
A
A
K
K
D4
330nF X2
K
K
A
NEUTRAL
This circuit is directly connected
to the mains and all parts operate
at 230VAC. As such, contact with
ANY part of the circuit could be fatal!
DO NOT operate this circuit unless
it is fully enclosed in the specified
junction box and DO NOT touch any
part of the circuit while it is connected to the mains.
Note that, in most states, a licensed electrician must be used to
connect this unit to fixed electrical
wiring.
RELAY 1
MAINS
ACTIVE
ACTIVE
TO LOAD
Warning!
ZD1
24V
220F
TIMER
(IC1)
A
A
A
D6
D2
470 1W
Fig.2: simplified circuit of the timer power supply. The mains is rectified
by diodes D3-D6, filtered with a 220µF capacitor and regulated by 24V
zener diode ZD1. A 220nF X2 capacitor in the Neutral leg limits the mains
current. Diodes D1-D2 work in conjunction with Relay1 to supply power for
the circuit after switch S1 is turned off, until the off-timer period expires.
August 2012 65
+24V
+24V
INSTALL
ONE LINK
ONLY
16
Vdd
100nF*
9
Ctc
O14
O13
O12
1M
10
O10
Rtc
3.3M
11
12
LK1
2
LK2
1
LK3
15
LK4
3.3M
20min
RS
O6
O5
Vss
8
O4
B
Q1
BC557
Q2
BC557
K
C
D5
C
5min
K
K
A
A
D1
D3
A
RELAY1
K
1min
D7
CON1
A
6
A
4
D9
5
7
K
K
1
A
2
K
470
A
+12V
22nF
X2
22k
220F
35V
ZD1
24V
1W
K
K
330nF
X2
A
A
K
10M 1W
D2
D6
SC
2012
* VALUE MAY BE CHANGED FOR
DIFFERENT DELAYS (SEE TEXT)
D4
A
BC557
B
D1-D8: 1N4004
A
MAINS TIMER FOR LIGHTS & FANS
K
A
K
N
K
A
D9: 1N4148
Asw
4
1W
0V
WARNING: ALL PARTS AND WIRING
IN THIS CIRCUIT MAY BE AT 230V AC
POTENTIAL WHEN OPERATING.
CONTACT COULD BE FATAL!
Aload
3
D8
1nF
Aperm
0V
ZD2
12V
1W
220nF
10k
100k
E
10min
13
E
B
O9
IC1
4060B O8 14
O7
MR
3
1M
E
C
ZD1, ZD2
A
K
Fig.3: the full circuit of the Mains Timer. IC1 is a 4060 CMOS oscillator/counter which provides the time delay. It
controls Relay1 to switch power to the load as well as the circuit’s power supply (refer to Fig.2). Diode D8 allows the
timer to sense when the mains switch is turned off; while it is on, the timer is held in reset as IC1’s MR input (master
reset, pin 12) is held high.
Relay1. So the circuit has no Active
connection until switch S1 is closed.
When S1 is closed, the mains voltage is applied across the bridge rectifier formed by diodes D3-D6. The output
is limited to 24V DC by zener diode
ZD1 and filtered by a 220µF capacitor.
The mains input current is limited in
the Neutral leg by a series 330nF X2
capacitor with a parallel 10MΩ bleed
resistor and a series 470Ω resistor for
in-rush current limiting.
Once the 220µF capacitor has
charged up, the timer circuitry energises the coil of Relay1 and its contacts
switch over. The incoming mains Active is then connected to the junction
of diodes D1 and D2 via the relay and
these are effectively in parallel with
diodes D3 and D4 in the bridge rectifier. But when switch S1 is turned off,
the circuit remains powered, via the
relay contacts and the bridge rectifier
formed by D1, D2, D5 & D6.
The circuit remains powered until
the timer runs its course, at which
point Relay1 is switched off and the
24V supply collapses, bringing it back
66 Silicon Chip
to the initial state, where it is not consuming any power.
Note that the circuit is powered
directly from the 230VAC mains and
floats at or near mains Active potential
so it must be considered as hazardous
(lethal) once it has been connected.
Also note that zener diode ZD1
dissipates little power as the 330nF
X2 capacitor value has been chosen
to limit the mains current to a value
very close to that drawn by the relay.
Details
Now take a look at Fig.3 which
shows the full circuit diagram. Besides showing the details of the timing
circuitry (at left), this also reveals an
additional diode (D8) which is connected to mains Active via switch
S1 (off board). This diode allows the
timer to sense when S1 is turned off
and this is the reason we didn’t simply
arrange for Relay1’s contacts to short
out the switch when it turns on. If we
had, there would have been no way to
sense when S1 is switched off.
While switch S1 is on, D8 is for-
ward-biased and so at the peak of each
mains cycle, current can flow through
it and its series 10kΩ current-limiting
resistor to charge the 1nF capacitor
between the MR (master reset, pin
12) and Vss (negative supply, pin 8)
terminals of timer IC1. While S1 is
on, MR is kept high and this holds the
timer in its reset state, with its oscillator inhibited and its 13-bit counter
reset to zero. While the counter is zero,
all its outputs (O4-O10 and O12-O14)
remain low.
Depending on how the timer is
configured, one of the four outputs
O10 or O12-O14 is connected to the
base of PNP transistor Q1 via a 3.3MΩ
resistor. That output being low, it sinks
current from the base of Q1, turning it
on. It in turn drives PNP transistor Q2,
which energises Relay1’s coil, turning
it on. One of its set of contacts supplies
mains power to the load and the other
connects the mains to this circuit, as
described earlier.
Note that Q1 and Q2 are in a PNP
Darlington configuration. The 1MΩ
resistor between Q2’s base and emitter
siliconchip.com.au
shunts any leakage current from Q1,
preventing a false turn-on.
When switch S1 is turned off,
current can no longer flow through
D8 and so the 1nF capacitor is discharged by its parallel 100kΩ bleeder
resistor. The 22nF X2 capacitor at the
anode of D8 is necessary to suppress
capacitively-coupled electrical noise
and leakage current through S1 from
keeping the MR pin high even when
S1 is off. When MR goes low, IC1’s
internal oscillator starts running and
incrementing the counter.
Oscillator frequency
The oscillator’s frequency is set by
the combination of the 100nF capacitor and 1MΩ resistor between pins 9
& 10 of IC1. The formula in the 4060
data sheet gives us 4Hz for these values
but we measured 7Hz on two different
prototypes so we use this measured
value and assume that the formula
must be inaccurate when such a high
resistor value is used (even though it
is within the specified range). So IC1’s
internal counter is incremented seven
times per second.
The 3.3MΩ resistor minimises frequency variation with supply voltage
by isolating the input capacitance of
pin 11.
IC1’s O10 output goes high after
512 (29) oscillations or 512 ÷ 7Hz =
73 seconds. Similarly, the O12 output
goes high after 5 minutes, O13 after 10
minutes and O14 after 20 minutes. So
depending on which of links LK1-LK4
is installed, after the selected delay, Q1
and Q2 switch off. This de-energises
the coil of Relay1 and diode D7 absorbs
the resulting back-EMF.
This cuts power to the load and the
Timer also powers down as the 220µF
capacitor discharges. If the mains
switch is turned back on before the
time-out (ie, while the load is still energised), the MR input of IC1 is pulled
high and so the timer is reset. When
the switch is turned off, the timer again
starts counting from zero.
We need 24V to drive the relay coil
but IC1 has a maximum rating of 15V
so the supply from the 220µF capacitor
is fed via a 22kΩ resistor to the 12V
zener diode, ZD2. This limits the supply for IC2 to +12V.
So while it might not be immediately apparent from the circuit of
Fig.3, the Mains Timer has two supply
rails: +24V and +12V. Note, however,
that IC1 (4060B) is actually connected
siliconchip.com.au
between the +24V and +12V rails.
Don’t be fooled by those low DC
voltages though – as stated, this whole
circuit “floats” at mains potential
(230V AC) and is potentially lethal.
The 220nF capacitor and 22kΩ
resistor also form a low-pass RC filter
to remove much of the 100Hz ripple
from IC1’s supply.
You might be wondering about the
purpose of diode D9. It stops the timer
from running once the relay switches
off. Normally, this isn’t an issue since
the power supply then collapses. But
without D9, if the delay was set short
enough, it’s possible the relay could
come back on while the mains switch
remained off.
Other uses
Up to now we have been describing
how the timer circuit is used with a
standard wall switch and in that case,
the timer provides an off-delay, ie, the
load is powered while ever the switch
is on as well as for the preset period
after it is switched off.
But this is no good if you want to
use the Timer to prevent the load from
being accidentally left on after use,
which can be a concern for both fans
and lights. If that’s your aim, you simply need to change the mains switch
to either a momentary push-button or
a spring-loaded momentary switch.
These are available from electrical
suppliers in the standard Keystone format to clip into a wall-plate. They may
be sold as a bell-press button or similar.
Parts List
1 PCB, code 10108121, 60 x
76mm
1 4-way PCB-mount (screw fix)
terminal barrier (CON1) (Jaycar
HM3162, Altronics P2103)
1 5A 24V DC coil DPDT or
DPST relay (Altronics S4195D
or equivalent)
1 junction box (eg, Arlec 9071)
2 M3 x 15mm machine screws
and nuts
4 M3 shakeproof washers
4 No.4 x 9mm self-tapping screws
Semiconductors
1 4060B oscillator/counter (IC1)
2 BC557 PNP transistors (Q1,Q2)
1 24V 1W zener diode (ZD1)
1 12V 1W zener diode (ZD2)
8 1N4004 1A diodes (D1-D8)
1 1N4148 small signal diode (D9)
Capacitors
1 220µF 35V/50V electrolytic
1 330nF 250VAC X2 MKT/MKP
(Element14 Part No. 1215460;
Altronics Cat. R3129)
1 220nF MKT polyester
1 100nF MKT polyester (see
panel below)
1 22nF 250VAC X2 MKT/MKP
1 1nF MKT polyester
Resistors (1%, 0.25W unless stated)
1 10MΩ 1W 5% 1 22kΩ
2 3.3MΩ
1 10kΩ
2 1MΩ
1 470Ω 1W 5%
1 100kΩ
1 0Ω
Changing The Switch-Off Time Delay
Four time delay options are available by default: one minute, five minutes,
10 minutes and 20 minutes. These are selected by installing one of links LK1,
LK2, LK3 or LK4 respectively. If none of these suit, you can change the value
of the 100nF MKT capacitor to give other time delays as shown in Table 1
below. Simply select the appropriate value and then install the corresponding link
to give the desired delay.
Note that these times are approximate and can vary by about ±20%, due to
component tolerances and rounding errors.
Table 1: Setting The Timing
C1
330nF
220nF
150nF
100nF
22nF
15nF
4.7nF
LK1
1 hour
45 minutes
30 minutes
20 minutes
4 minutes
3 minutes
1 minute
LK2
30 minutes
20 minutes
15 minutes
10 minutes
2 minutes
1.5 minutes
30 seconds
LK3
15 minutes
10 minutes
7.5 minutes
5 minutes
1 minute
45 seconds
15 seconds
LK4
4 minutes
2.5 minutes
2 minutes
1 minute
15 seconds
10 seconds
5 seconds
August 2012 67
D6
N
4004
IC1 4060B
100nF*
1nF
(LK4)
3 .3M
100k
10k
(LK3)
LK1
+
12V
1M
3 .3M
D5
C 2012
10M 1W
470 1W
4004
MAINS
NEUTRAL
D8
35V
D9
Mains
Timer
4004
1W ZD2
D4
22k
4004
22nF
X2
N
220F
4004
24V
SW
D2
1W ZD1
L
LOAD
(FAN OR
LIGHT)
N
E
(if present)
D3
Asw
D1
4004
4004
A
220nF
1M
A
Aperm
Aload
MAINS
EARTH
Q1
BC557
4148
(S4195D)
SWITCH
BC557
Q2
RELAY1
(LK2)
MAINS
ACTIVE
D7
4004
remiT
1210108121
180101
330nF X2
WARNING: ALL PARTS ON THIS PCB OPERATE AT MAINS
POTENTIAL (230VAC). CONTACT COULD BE FATAL.
Fig.4: follow this layout and wiring diagram to assemble the timer board. Take
care with the orientation of the diodes, the 220µF capacitor and IC1. Note that
only one link (LK1-LK4) is installed, giving four time options (see text and panel
for details on selecting the appropriate link).
The completed PCB fits into a junction box.
It’s shown here mounted on the base.
So if you swap the switch over to a
momentary pushbutton and wire in
the timer as shown above, the load
will then turn on for the chosen period
when the button is pressed and then
automatically turn off again. The button can also be pressed any time the
load is on, to reset the timer and keep
it on for the preset period.
Construction
The Mains Timer is built on a PCB
68 Silicon Chip
coded 10108121 (60 x 76mm). This fits
in a standard junction box (eg, Arlec
9071). But note that not all junction
boxes are the same and you will need
to check that the one you are purchasing has mounting holes in the same
positions as those of the PCB.
The PCB is available from the
SILICON CHIP Partshop. While it is
notionally a single-sided design, we
have made it double-sided and added
parallel tracks on the top to improve
its mains current-carrying capability.
In the absence of a kit being available,
we recommend you build the timer using one of our boards since they have
a solder mask which greatly reduces
the chance of leakage paths developing
and causing flash-over.
Referring to the PCB overlay diagram (Fig.4), start by installing all the
small resistors. Use a DMM to check
each as you go, since the colour codes
can be hard to read accurately. The
0Ω resistor is used for one of LK1LK4 and you must only install one of
these. Refer to Table 1 and select your
desired time-out, then fit the link (0Ω
resistor or tinned copper wire) in the
appropriate position.
Follow with the diodes, being careful with the orientation, and make
sure the smaller 1N4148 diode goes
in the top-right corner. Note that the
orientation of diodes D1-D6 and D8
alternates as you go down the board.
Install the two zener diodes (ZD1 &
ZD2) also. These are in a larger glassencapsulated package and both are
orientated with the cathode stripe
towards the top of the PCB.
Solder IC1 in place next, with the
pin 1 notch or dot towards the top
of the board as shown. Follow with
the two 1W resistors – don’t get them
mixed up. You can then fit the smaller
MKT capacitors. The 100nF capacitor
can be a different value if you want to
adjust the timing – see Table 1.
Now install the two transistors,
bending their pins with a small pair of
pliers to fit the pads provided. The flat
faces are orientated as shown on the
overlay diagram. You can then solder
the electrolytic capacitor in place, with
the longer (+) lead towards the top of
the board.
Follow with the two X2 capacitors.
Note that the larger X2 capacitor can
have one of several lead pitches so
multiple pads have been provided to
suit them all; its left-most lead should
go in the left-most hole provided and
the other into the best fitting position.
After that, solder the relay in place.
The terminal barrier is attached to
the PCB using two 15mm M3 machine
screws with a star washer under each
screw head and nut. Check that the
connector is straight and do the screws
up tight before soldering the four pins.
Use a hot iron to ensure that the solder
joints form proper fillets.
Finally, attach the PCB to the junction box baseplate using four small
siliconchip.com.au
self-tapping screws and you are ready
to test it.
Testing
If you have a bench supply and
would like to test the PCB before
it is installed and connected to the
mains, you can do so. Connect a DC
supply, set to slightly less than 24V,
across ZD1, with the positive lead to
its cathode (striped end). The circuit
should draw about 30mA so if it draws
much more than this, switch off and
check for faults.
The relay may or may not switch
on initially; if it does not, apply 24V
to the SW terminal of CON1 and it
should turn on. After the delay you
have selected, it should turn off again.
Assuming it does, the unit is working
correctly and you can power it down.
Otherwise, carefully check the component orientation, component values
and solder joints.
Installation
Note that, in most states, this unit
should be connected to the house
wiring by a licensed electrician only.
Note also that all parts on this circuit
operate at mains potential (230VAC),
so do not touch any part of the circuit
when power is applied.
It’s a matter of following the wiring
diagram (Fig.4) to make the connections. You must switch off the circuit
before you start working on it and
check that it really is off before starting work.
Ensure that the junction box baseplate is securely anchored to a joist
or ceiling batten using the supplied
screws before doing the wiring. Note
that you will need to knock out one or
two panels in the junction box housing
to allow the wiring to pass through.
The mains cables must be clipped or
clamped to convenient beams or joists
once you have finished. This keeps the
ceiling space (or wherever the unit
SILICON
CHIP
Fig.5: front panel label
for the Mains Timer. Print
this out, laminate it and
glue it to the lid of the
junction box (eg, using
silicone sealant) for future
reference.
MAINS TIMER
MAINS
ACTIVE
SWITCH
Aperm
Aload
MAINS
EARTH
Asw
A
E
(if present)
N
LOAD
(FAN OR
LIGHT)
PC BOARD
N
MAINS
NEUTRAL
WARNING: ALL PARTS INSIDE OPERATE AT 230VAC.
DISCONNECT FROM MAINS BEFORE SERVICING.
is installed) neat and prevents wires
from being tripped over, accidentally
yanked, etc. It also makes it easier to
trace the wires to see where they go.
In some cases, you may wish to use
a single switch to control both a light
and a fan – see Fig.1(c) for wiring
details. Now, both the light and the
fan will come on when the switch is
turned on but when it is turned off,
the light will go off immediately while
the fan will continue to run for the
programmed period before turning off.
If the fan has an existing earth connection, this should be left intact. Fans
with a metal housing will tend to have
an earth wire while those with a plastic
housing may not. If the earth wire has
to be cut, it can be re-joined using a
double-screw BP connector.
Once everything is hooked up,
check that all the terminal barrier
screws are tight and there are no stray
strands of copper from any of the wires
that might short to something else.
You can then clip the terminal barrier
covering in place, fit the junction box
cover, turn the power circuit back on
and check that everything is working
as expected.
Fans with 3-pin plugs
Many existing ceiling fans and all
new fans these days come fitted with a
lead complete with 3-pin mains plug.
This simply plugs into an adjacent
mains socket in the roof space.
In that case, a better idea may be to
ditch the junction box and install the
Mains Timer PCB in an IP65 sealed
box. This can then be fitted with a
socket, so that the fan can be plugged
into it.
Short delay
Finally, note that in operation, you
may notice a short delay between flicking the switch and the load coming
on. This is usually only a couple of
hundred milliseconds and is due to the
power supply capacitors charging to
the relay’s operating voltage. It’s short
enough that it should not present a
problem, especially when used with
fans, which take some time to spin
SC
up anyway.
Table 3: Capacitor Codes
Value
330nF
220nF
100nF
22nF
1nF
µF Value IEC Code EIA Code
0.33µF 330n
334
0.22µF 220n
224
0.1µF
100n
104
.022µF 22n
223
.001µF 1n
102
Table 2: Resistor Colour Codes
o
o
o
o
o
o
o
o
o
siliconchip.com.au
No.
1
2
2
1
1
1
1
1
Value
10MΩ
3.3MΩ
1MΩ
100kΩ
22kΩ
10kΩ
470Ω
0Ω
4-Band Code (1%)
brown black blue brown
orange orange green brown
brown black green brown
brown black yellow brown
red red orange brown
brown black orange brown
yellow violet brown brown
single black stripe
5-Band Code (1%)
brown black black green brown
orange orange black yellow brown
brown black black yellow brown
brown black black orange brown
red red black red brown
brown black black red brown
yellow violet black black brown
single black stripe
August 2012 69
By NICHOLAS VINEN
High-Current Adaptor
For Scopes & DMMs
If you want to measure and monitor mains current of up
to 30A using your DMM or scope, this is the safe and easy
solution. It works just as well with DC and it has significantly
better resolution and bandwidth than most clamp meters.
I
N THE SILICON CHIP laboratory, we
often need to hook our digital storage oscilloscope (DSO) up to mainspowered equipment to examine the
current waveforms. The two most
common ways to do this are with a
shunt resistor and differential probe
or a clamp meter. But both approaches
have drawbacks.
A shunt resistor connected in series
with one of the mains conductors (eg,
Neutral) provides the best bandwidth
and resolution but you need a differential probe (which can be expensive),
even if you are measuring on the Neutral leg since Neutral is usually a few
volts above or below Earth potential.
The resistor also limits how much
current you can measure depending on
its value. For example, a 0.1Ω 10W resistor limits you to measuring around
7A RMS (after de-rating by 50%). This
70 Silicon Chip
option can also be quite unsafe as the
wiring between the shunt and probe
is connected directly to mains.
A clamp meter is safer since it
doesn’t require any exposed mains
wiring. But they tend to have a fairly
low output voltage, eg, 1mV/A. This
gives you lousy resolution and noise
performance with scopes which usually have a maximum sensitivity of
5mV/div. Clamp meters also typically
have quite limited bandwidth (eg,
10kHz) which is no good for loads with
fast-changing current waveforms such
as switchmode supplies.
Also, you need to separate out the
mains conductors to use a clamp meter
since if you just clamp it over the cable,
the Active and Neutral currents are of
identical magnitude and opposite in
direction so the magnetic fields effectively cancel. So you need some kind
of special cable or adaptor to measure
mains current with a clamp meter.
Our solution
With our adaptor, you get much
higher bandwidth and resolution than
a clamp meter (80kHz, 100mV/A) with
better safety than a shunt resistor, no
need for a differential probe and at a
fairly low cost.
We use an Allegro ACS712 IC,
which like a clamp meter operates on
the Hall Effect principle but the whole
shebang is within a single chip. One
side of the IC contains a 1.2mΩ shunt
which can handle a continuous current of at least 30A and pulses up to
100A for 100ms. On the other side is
a fully isolated Hall Effect sensor and
amplification circuitry.
There is no electrical connection
between the two halves; sensing is
siliconchip.com.au
purely based on the magnetic field
generated by current passing through
the shunt. The chip has an isolation
rating of 1500VAC between the two
halves so the output can safely be
hooked up to a scope or other device
even if you are measuring mains current at up to 250VAC.
There are three versions of this IC,
designed for sensing currents up to
±5A, ±20A and ±30A. They are otherwise identical. For our prototype, we
used the 20A version since its output
is 100mV/A and this makes it easy to
set up our scope to read out directly
in amps (by telling it we have a 10:1
current probe). We run it from a 5V
supply, giving readings of up to ±25A
although linearity is a little degraded
at the extremes.
The 30A version has an output of
66mV/A and can read up to ±38A. You
can use this one if you prefer but then
you may need a calculator to interpret
the readings.
Power comes from a 9V battery because this is much more convenient
than a plugpack when setting up a
test. We fitted ours with a mains plug
and socket for measuring the current
drawn by mains devices however it
could also have been fitted with DC
connectors if that’s what we wanted to
measure. The output is a BNC socket,
making it easy to hook up to a scope.
For connection to a DMM, we use a
BNC plug to banana socket adaptor.
So that you can’t accidentally leave
the unit on and drain the battery (easy
to do!), we incorporated an automatic
time-out which switches the unit off
after about 15 minutes. If you want to
use it for a longer period, you just have
to remember to periodically press the
power button to keep it on.
Specifications
Accuracy: approximately 2% error
Bandwidth: typically 80kHz
Range: ±25A* (linear over ±20A)
Output: 100mV/A*
Noise: ~40mV peak-to-peak
(equivalent to ~400mA)
Power supply: 9V battery, approximately 20 hours life
Resistance: ~2mΩ plus cable
resistance
Isolation: 2.1kV RMS (suitable for
use up to 250V AC)
Withstand current: 100A for
100ms
Other features: power indicator,
auto-off to preserve battery life
* With alternative shunt IC, range increases to ±38A (linear over ±33A)
with 66mV/A output
Circuit description
Refer now to the circuit diagram
in Fig.1. The power supply is shown
at left while the actual current sense
portion of the circuit is at lower right.
IC3 is the ACS712 shunt monitor IC.
In addition to a 100nF power supply
bypass capacitor, it has a 1nF filter capacitor from pin 6 to ground. This sets
its bandwidth to 80kHz and provides a
good compromise between bandwidth
and residual noise. The shunt side
of the IC, at left, is connected to two
terminals of a 4-way terminal barrier,
which is then wired to the mains plug
and socket.
If you increase the value of the filter
capacitor at pin 6, the residual noise
is reduced but so is the bandwidth.
For example, if you use 10nF instead
of 1nF, bandwidth drops to 8kHz and
noise to ~20mV (200mA) peak-topeak. If you use 100nF then bandwidth
drops to 1kHz and noise to ~10mV
(100mA) peak-to-peak. If unsure, stick
with the recommended value of 1nF.
IC3’s output is at pin 7 and sits at
half supply (about +2.5V) when there
is no current flow. This is buffered by
IC4a, half of an LM358 dual low-power
op amp. Its is biased into Class-A operation with a 10kΩ resistor from its
output pin 1 to ground (The LM358
data sheet explains why this is neces-
sary). A 100Ω series resistor prevents
instability that may occur due to output cable capacitance and the signal
is available at the “+” output of CON2.
Ideally, we want 0V across CON2
when no current is flowing, rather than
2.5V, so we generate a half-supply rail
at around +2.5V and connect that to
the negative output terminal of CON2,
so there is no voltage across it in the
quiescent condition.
This is achieved using a voltage divider consisting of two 10kΩ resistors
and 500Ω trimpot VR1. The voltage at
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EMONA
August 2012 71
72 Silicon Chip
siliconchip.com.au
D1
1N5819
47k
K
A
10M
100nF
47k
D2
3.3M
1M
47nF
K
A
11
10
9
12
RS
Rtc
Ctc
MR
D5
14
13
15
1
2
8
Vss
O4
O5
O6
O7
7
5
4
6
O9
IC2
4060B O8 14
O10
O12
O13
3
7
IC1c
IC1d
O14
9
8
13
12
10k
16
Vdd
3.3M
100nF
A
10
11
D7
K
6
5
2
1
N
IC1b
IC1a
IC1: 4093B
100nF
E
A
K
A
B
OUT
IN
N
E
A
K
A
K
A
(IN S1)
D4
E
N
4
3
2
1
IP–
IP–
IP+
IP+
LED1
K
A
D3
6.8k
OUTPUT
SOCKET
1
2
3
4
CON1
470nF
VIA CON1,
TERMINAL 4
D6
C
VIA CON1, TERMINAL 3
INPUT
PLUG
4
3
22k
E
Q1 BC559
GND
5
OUT
VIout
FILTER
6
7
100nF
GND
IC3
ACS712
8
Vcc
IN
REG1
LP2950ACZ-5.0
1nF
10k
100nF
K
A
K
1N5819
A
D2-D7: 1N4148
10k
VR1
500
+5V
100 F
+5V
+8.7VSW
IC4a
8
6
5
8
1
1
4
10k
7
10k
ACS712
4
IC4b
IC4: LM358
2
3
100nF
E
IN
B
OUT
C
BC559
GND
LP2950ACZ-5.0
100
–
CON2
+
100
OUTPUT
TO SCOPE
OR DMM
Fig.1: the full circuit of the Current Adaptor. Connections are shown for measuring the mains current but it can also be used to measure low-voltage AC or
DC current. Current flows through IC3’s internal shunt and a proportional voltage appears at its VIout terminal (pin 7). Op amp IC4 buffers this voltage and
a half-supply rail to provide differential output voltages at CON2. IC3’s 5V rail is derived from a 9V battery via low-dropout regulator REG1 and switched
by transistor Q1, which is controlled by a flipflop formed by IC1a & IC1b. The unit is turned on by a short press from momentary pushbutton S1 and turned
off by a long press or after 15 minutes by timer IC2. This prevents the battery from being discharged if the unit is accidentally left on; the timer can be reset
with a brief press of S1.
ISOLATED HIGH-CURRENT ADAPTOR FOR SCOPES & DMMS
100nF
9V
BATTERY
2012
SC
A
K
POWER
S1
+8.7V
Parts List: Isolated High-Current Adaptor
1 PCB, code 04108121,
60 x 107mm
1 UB3 jiffy box
1 right-angle PCB-mount tactile
pushbutton with blue LED (S1)
(Altronics S1181)
1 500Ω mini sealed horizontal
trimpot
1 9V battery holder, PCB-mount
1 9V battery (alkaline or lithium
recommended)
1 4-way PCB-mount (screw fix)
terminal barrier (CON1)
(Jaycar HM3162)
1 2-way polarised header, 2.54mm
pitch (CON2)
1 2-way polarised header
connector, 2.54mm pitch
1 female BNC panel-mount socket
(Jaycar PS0658, Altronics
P0516)
1 100mm length of light duty
figure-8 cable or ribbon cable
3 M2 x 6mm machine screws
2 M3 x 15mm machine screws
4 M3 nuts
2 M3 flat washers
VR1’s wiper is filtered with a 100nF
capacitor and buffered by op amp IC4b,
the other half of the LM358. VR1 is adjusted so there is 0V across CON2 with
no current through the shunt. CON2 is
normally wired to a BNC socket with
the negative pin side to its shell.
IC4, the LM358, runs off the +8.7V
(nominal) switched rail from the battery so that both outputs have a full
0-5V swing. However, note that once
the battery has dropped below 6.5V
(when it’s quite flat), the full swing
may no longer be available. This could
result in low readings towards the end
of the battery’s life.
To improve performance in this
respect, an LMC6482 rail-to-rail op
amp can be used in place of the LM358
and this will operate normally with a
battery voltage down to 5V. However,
the LMC6482 draws slightly more supply current; about 1.5mA compared to
0.5mA for the LM358, so the battery
life will be slightly less.
Power supply
The ACS712 isolated shunt IC (IC3)
runs from a regulated 5V rail, drawing
about 10mA. This is controlled using
momentary pushbutton S1 which also
siliconchip.com.au
2 M3 star washers
2 M3 x 10mm tapped Nylon
spacers
1 M3 x 15mm tapped Nylon spacer*
3 M3 x 6mm Nylon machine
screws
1 sheet of Presspahn insulation,
70 x 30mm*
1 mains extension cord with
moulded plug and in-line
socket*
2 cord-grip grommets to suit 7.48.2mm cable (Jaycar HP0716,
Altronics H4270)*
5 small cable ties*
Semiconductors
1 4093 CMOS quad Schmitt
trigger NAND gate (IC1)
1 4060 CMOS oscillator/counter
(IC2)
1 ACS712ELCTR-20A-T
(Element14 1329624) OR
1 ACS712ELCTR-30A-T
(Element14 1651975)
1 LM358 dual op amp (IC4)
1 BC559 PNP transistor (Q1)
has an integrated blue LED. This LED
lights up when the unit is on. When
on, pressing S1 briefly resets the autooff timer while holding it down for a
second or two turns the unit off.
The power on/off control and autooff timer functions are provided by
IC1, a 4093B quad CMOS Schmitt
trigger NAND gate IC and IC2, a 4060B
CMOS oscillator/counter. Both these
ICs are permanently powered by the
battery but being static CMOS logic,
only draw a tiny amount of current,
typically <1µA. This is probably lower
than the battery’s self-discharge current so it will last many years with the
unit switched off. Schottky diode D1
provides reverse polarity protection.
NAND gates IC1a and IC1b are
configured as an RS-flipflop which
controls power to IC3 and IC4. When
the unit is off, output pin 3 of IC1a is
low and output pin 4 of IC1b is high.
Therefore, PNP transistor Q1 has no
base drive and so no current can flow
through its collector-emitter junction
and into the rest of the circuit.
The high output from pin 4 in this
state also forward biases diode D6,
pulling pin 12 of IC2 (MR or master
reset) high. This prevents IC2’s oscil-
1 LP2950CZ-5.0 low dropout, low
quiescent current 5V regulator
(REG1) (Jaycar ZV-1645,
Element14 1262363)
1 1N5819 1A Schottky diode (D1)
6 1N4148 small signal diodes
(D2-D7)
Capacitors
1 100µF 16V electrolytic
1 470nF MKT
7 100nF MKT
1 47nF MKT
1 1nF MKT
Resistors (0.25W, 1%)
1 10MΩ
1 22kΩ
2 3.3MΩ
5 10kΩ
1 1MΩ
1 6.8kΩ
2 47kΩ
2 100Ω
* For measuring mains current,
substitute different parts for DC or
low-voltage AC current measurement.
Note: the PCB is available from
the SILICON CHIP Partshop.
lator from running, minimising its
power consumption. Less than 1µA
flows through the 10MΩ pull-down
resistor.
When pushbutton S1 is pressed, two
47kΩ resistors, a 100nF capacitor and
diode D2 provide a delay to debounce
the switch. The delay is around 28ms,
whether the button is being pressed or
released. Because IC1d has Schmitttrigger inputs (ie, inputs with hysteresis), the resulting slow rise and fall
times are not an issue.
When S1 is pressed, input pin 12
of NAND gate IC2d goes high and assuming pin 13 is high (more on this
later), its output pin 11 goes low. This
sets the RS-flipflop, sending pin 3 high
and pin 4 low, turning on Q1 and thus
the rest of the circuit.
Pin 13 of IC1d is driven by IC1c.
IC1c’s inputs (pins 8 & 9) are tied together so that it operates as an inverter.
It is fed from a further delayed version
of the pushbutton signal; the 3.3MΩ
resistor and 100nF capacitor form an
additional low-pass filter which adds
a delay of roughly two seconds. This
means that the input to IC1c is still low
when pin 12 of IC1d goes high; thus
pin 13 of IC1d is also high.
August 2012 73
5819
9V BATTERY
HOLDER
1nF
100nF
2
CAV 0 3 2
100nF
10k
M3 x 15MM
NYLON SPAC ER
AC S712
(UNDER)
1
100nF
IC 1 4093B
1M
3.3M
REG1
LP2950AC Z-5
C
47k
4148 D2
3.3M
47k
D5
4148
4148
D6
47nF
100 F
22k
470nF
10k
4148
D7
100nF
10k
BC 559
04108121
Q1
VR1
+
IC 4
LM358
10k
100nF
10M
500
100
S1
D4
4148
4148
100nF
D3
IC 2 4060B
6.8k
OUT
–
+
3
IC 3
AC S712
4
!R E G NA D
s M M D &OUT
sepo cINS rof rNotpadAE tnerru C
WARNING: LIVE 230V!
2102 C
C urrent Adaptor
TOP OF BOARD
If S1 is held down, after this two second delay, the second 100nF capacitor
charges up, bringing input pins 8 & 9 of
IC1c high. IC1c’s output therefore goes
low. Since IC1c also drives an input
of IC1d, IC1d’s output simultaneously
goes high. This condition, with input
pin 6 of IC1b low and input pin 1 of
IC1a high, resets the RS-flipflop, pulling the base of Q1 high and switching
the unit off.
When pushbutton S1 is released,
pin 12 of IC1d goes low before pins 8
and 9 of IC1c do, due to the different
time constants of the two low-pass
RC filters. This is important so that
the unit stays off when S1 is released.
Auto-off timer
Alternatively, if pushbutton S1 is
only pressed briefly while the unit is
on, the 3.3MΩ/100nF RC filter does not
have time to charge fully and so the
unit does not switch off. But diode D5
will still become forward-biased and
this pulls IC2’s MR pin high, resetting
the auto-off timer.
Once S1 has been pressed, the
timer (IC2) runs for about 15 minutes
and then switches the unit off. This
time is set by the timing capacitor
74 Silicon Chip
04108121
D1
12180140
DANGER!
1
Fig.2: the PCB overlay
diagram for the Current
Adaptor. IC3, the ACS712
hall-effect shunt monitor is
soldered to the underside
as shown. A slot in the
board prevents surface
contamination from
forming a leakage path
between the high and low
voltage sides of the IC. The
current to be measured
flows between the “IN” and
“OUT” terminals of the
terminal barrier at bottom
and the output voltage
appears across the 2-pin
polarised header at upper
left, just below the 9V
battery holder. Pushbutton
switch S1 at upper-right
provides on/off control,
timer reset and power
indication via its in-built
blue LED.
230VAC
C urrent Adaptor for Scopes & DMMs
C 2012
UNDERSIDE OF BOARD
and resistor (47nF and 1MΩ), which
give an oscillator frequency of around
8.5Hz. Output O14 (pin 3) goes high
after 213 = 8192 clocks and this gives
8192 ÷ 8.5Hz = 963 seconds or about
15 minutes.
When O14 goes high, this forwardbiases diode D7 which charges the
100nF capacitor at pins 8 & 9 of IC1c
via a 10kΩ resistor, resetting the RSflipflop and switching the unit off.
Regulator
When Q1 is on, it supplies the
~8.7V from the battery to REG1, a
low-dropout, low quiescent current
5V linear regulator. This draws less
power from the battery than a 78L05
would and also allows the unit to
continue operating down to a lower
battery voltage.
The power LED integrated within
S1 is powered from the 8.7V rail
via two series 1N4148 diodes and a
6.8kΩ resistor to limit the current.
The two diodes cause the LED to dim
significantly as the battery voltage
drops below about 6V, since the LED
has a forward voltage of around 3.3V
and the two diodes add another 1.2V
to this. This gives a low battery indica-
tion before the voltage drops too low
for the device to function.
Construction
The unit is built on a PCB coded
04108121 and measuring 60 x 107mm.
This is available from the SILICON CHIP
Partshop. It’s designed as a singlesided PCB with one wire link although
we supply a double-sided PCB with
that link already present (as a track
on the top layer).
IC3, the ACS712, is a surface-mount
device (SMD) in an SOIC-8 package
and this goes on the underside. There
is a slot down the middle of its mounting position, to maximise electrical
isolation between the shunt and lowvoltage sides. If you have made your
own PCB, you should drill a series
of 1.2mm holes between the IC pads
where shown and file them into a slot.
The first job is to solder this IC in
place. It must go in with its pin 1 (indicated with a divot, dot or bevelled
edge) towards the bottom of the PCB,
as shown in the PCB overlay diagram
(Fig.2). The PCB indicates the correct
orientation too.
Put a small amount of solder on
one of the pads with the IC resting
siliconchip.com.au
Fig.3: the correct
cut-out to make
sure the cord-grip
grommets do grip.
Don’t be tempted
to simply drill a
16mm hole!
The completed PCB, without the two corner mounting posts. We used IC
sockets for our prototype but it’s better to solder the ICs to the PCB so they
can’t come loose if the unit is dropped. Once the wires have been connected
to the screw terminal block, the clear cover is clipped in place (not shown).
alongside, heat the solder and slide
the IC into place. If it isn’t aligned
properly on its pads, reheat the solder
and nudge it. Repeat until it is correctly aligned, then solder the rest of
the pins. Finally, re-solder the initial
pin, to ensure the solder has flowed
correctly, making a good joint.
Next, fit all the horizontally-mounted resistors, checking their values
with a DMM. You can also refer to
the resistor colour code table below.
Follow with the diodes, being careful to orientate them as shown on the
overlay diagram. Make sure that the
larger Schottky diode (D1) goes at
upper-right as shown.
Next, solder the DIP ICs in place. In
each case, the pin 1 notch or dot goes
towards the top of the board. Don’t
get the 4060 and 4093 mixed up. We
recommend you solder them directly
to the PCB so that they can’t come
loose and float around inside the box
(rather than using sockets).
Fit the MKT capacitors next. There
are four different values and they go
in the locations shown on the overlay
diagram. Then mount transistor Q1
and regulator REG1 which are both
in TO-92 plastic packages; check the
markings so you don’t get them mixed
up. You can then install the single electrolytic capacitor (longer lead toward +
symbol) and the polarised pin header,
followed by the remaining resistors
which go in vertically.
Trimpot VR1 can go in next, followed by pushbutton switch S1. You
may need to bend the latter’s leads
slightly to get them to fit the holes as
they are quite delicate and can easily
be bent out of shape during transport.
That done, use three short M2 machine
screws to attach the battery holder to
the board, then solder the leads.
Table 1: Resistor Colour Codes
o
o
o
o
o
o
o
o
o
siliconchip.com.au
No.
1
1
1
2
1
5
1
2
Value
10MΩ
3.3MΩ
1MΩ
47kΩ
22kΩ
10kΩ
6.8kΩ
100Ω
4-Band Code (1%)
brown black blue brown
orange orange green brown
brown black green brown
yellow violet orange brown
red red orange brown
brown black orange brown
blue grey red brown
brown black brown brown
Suits
7.4-8.2mm
cable
15.9mm
14mm
That just leaves the terminal barrier,
which is mounted using M3 screws
with flat washers under the heads and
star washers between the nuts and
PCB. Do up the screws tight, check that
it is parallel with the edge of the board
and then solder the pins, using a hot
iron and a generous amount of solder.
The PCB assembly can now be
completed by attaching three tapped
Nylon spacers. As shown in one of the
photos, the two M3 x 10mm spacers
are attached to the two corner holes
adjacent to the terminal strip (ie, on
the underside of the PCB) using M3 x
6mm Nylon screws.
The M3 x 15mm Nylon spacer goes
on the top of the board as shown in
Fig.2 and is also attached using an M3
x 6mm Nylon screw. It’s used to help
retain a Presspahn isolation barrier.
Testing
Check that the power supply works
by connecting the battery and pressing
the pushbutton. The blue LED should
light up. Hold down the pushbutton
for a couple of seconds and check that
it goes off. Then set the trimpot to its
mid-position, turn the unit back on
and measure the voltage across the
polarised pin header. It should be
Table 2: Capacitor Codes
Value
470nF
100nF
47nF
1nF
µF Value IEC Code EIA Code
0.47µF 470n
474
0.1µF
100n
104
.047µF 47n
473
.001µF 1n
102
5-Band Code (1%)
brown black black green brown
orange orange black yellow brown
brown black black yellow brown
yellow violet black red brown
red red black red brown
brown black black red brown
blue grey black brown brown
brown black black black brown
August 2012 75
The unit all wired up and ready to go. Note how the 2-wire ribbon cable for the output signal is clamped by the PCB.
There isn’t a lot of room for the output connector next to the battery so we had to trim its central solder pin. You can
also see how the Presspahn cover is held in place by the plastic case slots, terminal block and tapped spacer.
less than ±250mV. Adjust it as close
to zero as you can, using the trimpot,
then switch it off again.
Preparing the case
The next step is to drill a 5mmdiameter hole in the side of the case
for the on/off pushbutton. This hole is
positioned 22mm down from the top
lip of the case (ie, not including the
lid) and 47.5mm from the output end
(again as measured from the top lip).
You can then drop the PCB into the
case at an angle, to check that the hole
lines up correctly when the PCB snaps
into place. If not, enlarge it slightly.
Next, make the holes for the output
socket(s). We simply drilled a 9mm
diameter hole in the middle of the
end for the panel-mount BNC socket
but you could use a pair of binding
posts if you want. Keep in mind that
there is only about 11mm of clearance
from the battery to the end of the case
so whatever you use, it can’t intrude
very far. In fact, before installing the
BNC socket, we had to cut off most
of the central prong since it stuck out
too far (you only need a short section
to solder to).
Remove the PCB and fit the BNC
socket. Crimp and solder a 70mm
length of light-duty figure-8 cable
to the two polarised header pins,
then push the pins into the moulded
plastic housing. Solder the other end
of these leads to the rear of the BNC
socket, with the lead from pin 1 on the
polarised header (normally indicated
on the plastic housing) going to the
BNC shield while pin 2 goes to the
central pin.
Mains leads
Two M3 x 10mm tapped Nylon spacers are
fitted to one end of the PCB as supports.
76 Silicon Chip
If you are not planning on using
the adaptor with mains, you can use
binding posts or whatever you prefer
to make connections to the terminal
barrier. However this section will
describe the procedure for connecting
mains cables.
The first step is to cut the extension
lead in half. Strip away about 50mm
of outer insulation from both ends and
then expose 7-8mm of insulation from
each Active and Neutral wire and 1520mm for the Earth wires.
You will then need to make two
holes in the case, at the opposite end
to the BNC socket. These are spaced
25mm apart, on either side of the
centre of that end and have a diameter
of 14mm. Start with a smaller hole
(4-5mm say) and then enlarge using
a tapered reamer or stepped drill bit.
Make sure you don’t make the holes
too large since the cordgrip grommets
need to be a tight fit. Then profile the
holes to the shape shown in Fig.3,
using a file. Again, be careful not to
make the opening too large.
Now place one of the mains leads
through one of the cord-grip grommets, with the bare leads towards the
narrower end. Squeeze the grommet
together hard using large pliers (or if
you’re lucky enough to have one, a
grommet insertion tool), so that only a
short length of the cable’s outer insulation protrudes from that narrow end.
Push the grommet into one of the
holes and it should snap into place.
If it won’t go, enlarge the hole very
slightly and then try again. Be careful
since once it’s in, it’s very hard to get it
out. Do the same with the other cable
and grommet into the other hole.
Now check that the two mains cords
are securely anchored. You must not
siliconchip.com.au
This close-up view shows how the Presspahn cover is held
in place by the plastic case slots, the mains terminal block
and the M3 x 15mm tapped spacer.
be able to pull the cords out of the case,
even if you exert considerable force.
That done, connect the two Active
wires to the terminals marked “IN”
and “OUT” on the PCB. For correct
output polarity, “IN” should go to the
plug and “OUT” to the socket (current
flowing from IN to OUT will give a
positive output voltage). Do these up
tightly, too.
Twist the two Neutral wires together
and screw them down tightly to one
of the spare the terminals on the PCB
(see photo). Do the same for the Earth
wires. Make sure both are secure. You
can then use several small cable ties to
hold the wiring in place. These must be
installed to prevent individual leads
from moving and contacting other
wiring if they come loose.
Once these are in place, clip the
clear cover on top of the screw terminal block.
Presspahn barrier
The next step is to fit a Presspahn
insulation barrier between the mains
terminal block and the low-voltage
section of the PCB. This insulation
barrier is retained by the adjacent
slots in the side of the case and must
be trimmed to exactly 63 x 25mm so
that it is a tight fit.
As shown in the accompanying
photo, this barrier is sandwiched between the screw terminal block and
the adjacent M3 x 15mm Nylon spacer.
If necessary, rotate the spacer slightly
so that one of its lobes presses the
Presspahn insulation firmly against
the screw terminal block.
siliconchip.com.au
The completed unit with the lid in place. Note how the
illuminated on/off pushbutton switch protrudes through
a hole in one side of the case.
Do not leave the Presspahn barrier
out – it makes it impossible for any of
the mains wiring to contact the lowvoltage section of the PCB and is an
important safety measure.
Note that once the lid is in place,
the Presspahn barrier is also clamped
between the lid and the PCB.
A BNC plug-to-banana
socket adaptor can be
fitted to the BNC output
socket if you want to
connect a DMM.
Final assembly
Plug in the polarised header and put
the lid on the box. Then use a DMM to
make some checks before connecting
the device up:
(1) Check that the Earth terminals on
the mains plug and socket have a very
low resistance between them (should
read zero or very close to it).
(2) Do the same check between the
Neutral terminals and then for Active.
(3) Check that there is no connection
between all three pairs of terminals on
the mains plug and then on the socket
(ie, many megohms; meter should
normally read “0L” or similar).
(4) Check that there is no connection
between both terminals of the BNC
socket and all the mains terminals;
again, the meter should read “0L”.
Now plug the unit into mains and,
without touching anything, switch on
and measure the AC voltage between
the BNC shield and Earth using a
DMM. It should be just a few volts. Do
the same check with the BNC centre
pin. Only when you have ensured that
there is no mains voltage on these two
conductors should you connect the
BNC output to an oscilloscope.
You can then do a functional test by
connecting an appliance with a known
current to the output. For example, if
you use a 1kW bar radiator, its current
should be about 2.4A, depending on
the actual value of the mains voltage.
You can then monitor the current with
a DMM or oscilloscope. Check that you
get a sensible reading.
Assuming all is well, disconnect
your test load and check the DC output level of the adaptor. It should be
close to zero. If not, disconnect all
mains cables, open the unit up, make
sure it is switched on and adjust the
trimpot again.
We found that the offset changed
slightly the first time we used the unit
to measure a high current, so you need
to do the final trimming at this stage
to guarantee a low offset.
That’s it; using the device is simply a
matter of plugging it in and switching
it on. Don’t forget to periodically reset
the timer if you are undertaking a long
SC
test or measurement session.
August 2012 77
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connectors have a vice like
grip. Suits red, blue and
yellow kwik connector lugs.
SAVE 27%
29
$
T 1552A
Check out our
160pc crimp
multi-pack to suit.
H 1800 $19.95
Perth WA: 174 Roe St
Balcatta WA: 7/58 Erindale Rd
Auburn NSW: 15 Short St
Springvale VIC: 891 Princes Hwy
SAVE 17%
Q 0576
25
$
IP65
Temperature Module
Reads from -30°C to +70°C
with 0.1°C resolution. Build it
into your next project!
Size: 69L x 34W x 24Hmm.
29
$
SAVE 15%
S 0090
Mini Timer Module
May be used to extend the
activation time for a momentary
contact (1 to 180s). Triggered
by NC or NO contacts. 12-24V
AC/DC operation. Max 3A.
Phone Order Now On...
1300 797 007
siliconchip.com.au
or shop online 24/7 at www.altronics.com.au
S 9902A pictured.
Top Camera Deals!
539
Now with remote
smartphone monitoring
$
SAVE $60
S 9116C
Just add a hard drive and go!
TOP VALUE!
69
$
PRICE BREAK-THROUGH!
Affordable D-I-Y CCTV Surveillance Packages
0.01 Lux 420 line resolution Sharp® CCD Sensor
Great size for a small business or family home. Simply add a hard drive (see right) and plug it in! Each
pack includes: • 4 channel H.264 digital video recorder • 4 pro grade cameras • 4 x 20m BNC &
power combo leads • Power splitter lead • Power supply • Easy to follow instructions.
S 9900A includes 4 x weatherproof dome cameras. S 9901A includes 4 x weatherproof bullet
cameras. S 9902A includes 2 x bullet cameras & 2 x dome cameras.
4 Channel H.264 recording
Weatherproof cameras
Live smartphone viewing
Colour Ceiling Dome Camera
Seagate® Hard Drives To Suit
• 3-axis adjustable • Low noise • M 9272B
plugpack to suit $17.95 • 94Øx85mm
D 5513A 1TB $129
D 5515 2TB $176
Motion triggering
Secure your home or business for less!
S 9138A
SAVE $15
60
$
NESS Navigator D8x 8 Zone Alarm System
®
305
$
A breakthrough in price and functionality for touchscreen operated alarm systems. It offers an
intuitive ‘plain English’ interface with no LED’s or LCD icons to interpret - you may not even need the
manual! Eight alarm zones are provided, plus four auxiliary outputs. These could be used to control
security lighting, door strikes or CCTV activation. It could even control devices such as a pool pump,
garage door opener or sprinkler system. Dialler function can call up to 2 numbers when alarm is
tripped. This can be used with a monitoring company or as a personal notification. Includes control
box with alarm circuitry, keypad, backup battery, mains plugpack, tamper switch & telephone
connection lead.
Proudly Made In Australia
S 5281
Extra Keypad
$218
SAVE $35
IP66 Weatherproof
0 Lux
420 line resolution 20m Infra-Red Range
All-Weather Bullet CCD Camera
• Fully sealed metal enclosure • Day/night
• M 9272A plugpack to suit $17.95.
S 5280
S 9133A
NEW!
Full colour touch
screen for easy
operation & setup
189
$
High resolution!
0.001 Lux
Weatherproof
700 Line Resolution
High Resolution Bullet CCD Camera
See our YouTube
demo’s on the
website!
• Fully sealed metal enclosure • Day/night
• M 9272A plugpack to suit $17.95.
SAVE $20
179
$
SAVE $20
SAVE $120
449
$
S 9432
In-Car DVR With Flip Screen
GPS Synchronised to Google Maps.
Ideal for fleet monitoring: trucks, coaches, vans
and cars! Records 1080p high definition
footage of outside of vehicle - day or night.
3” LCD flip-down monitor for easy monitoring &
review. Includes 8GB micro-SD card. G-Sensor
can trigger recording under heavy braking.
S 9247
SAVE 20%
33
$
/pr
Video & Power UTP Baluns
Sends video signal and power to your camera
up to 100m away. Uses Cat5e cable, far
cheaper than coax! Sold in a matching pair - no
power required.
siliconchip.com.au
Rear
S 9290
SAVE $30
79
99
$
Composite To VGA Converter
Connect a CCTV system to a PC monitor!
Displays a composite signal up to high
resolution, ‘flicker free’, SXGA 1280x1024. BNC
input, DE15 VGA output. Requires M 9274A
12VDC plugpack $25.25.
$
Jumbo Remote Control
Open/Closed LED Sign
S 9123B
X 2810
High brightness long life LED sign with
remote control & flashing mode. Includes
power supply and hanging chains.
Size: 170H x 410W x 50Dmm.
Vandal Resistant
0.001 Lux
Weatherproof
700 Line Resolution
Varifocal Hi-Resolution Dome Camera
SAVE 16%
75
$
• Top quality picture • Metal housing • 4-9mm
varifocal • M 9273A plugpack to suit $16.95.
S 5335
S 9131
S 9753B
SAVE 22%
SAVE $30
99
$
9 Output CCTV Power Supply
A central CCTV power supply providing
9 x 12VDC outputs, each at 500mA.
Individually fused. Plugs into a standard mains
outlet. Size: 203W x 203H x 54Dmm
Express Order
Hotlines:
Shop Door Minder With Chime
Compact infra-red door beam announces
whenever customers arrive. Alarm or chime
mode settings. Adjustable volume. Sets up
in just minutes with no expertise required!
Includes power supply.
Optional Customer Counter S 5336
Phone: 1300 797 007
Fax: 1300 789 777
www.altronics.com.au
$39.95
70
$
Just 3cm long!
0.5 Lux
Mirrored video output
Easy to install
Compact Car Reversing Camera
• CMOS sensor • Fits easily into a number
plate recess • IP65 • 12-15V DC.
August 2012 79
ONE-STOP ELECTRONICS SHOP
SAVE $50
349
Opus One®
180W Subwoofer
Sensation!
325
$
Opus One® 2 x 100W Stereo AM/FM Receiver
Expand your home audio system to the study or entertainment area. Features five
stereo RCA inputs, front panel input for iPod, in-built AM/FM tuner and A/B speaker
selection. Includes remote. Size: 430x283x80mm.
A 2691A
SAVE $50
$
C 5201
Add cinema like realism to your
home theatre sound system.
Massive 180W 10” driver with
built in amp. A stunning
frequency response of 35Hz1KHz. Level, phase &
crossover control built in.
RATTLE THE
FLOORBOARDS!
“Best value subwoofer we’ve used.
Even compared to big brand name
models costing twice as much”
- Ashley, Retail Music Systems
SAVE $71
369
$
2 Year Warranty
Biema® Stereo Power Amplifier - Up to 350W per channel!
Extraordinary value for money! Brilliant performance, producing a smooth, crisp sound
with plenty of grunt when required. Features • 6.35mm/RCA inputs • Fan cooled
• Binding post, 6.35mm & Speakon outputs • Host of protection features • Power into
4Ω 2 x 350W • Power into 8Ω 2 x 200W.
A 4156 2x200W
SAVE $76
299
$
Upgrade Your Audio System
SAVE $20
79/pr
$
C 8867B Handheld Pack
C 8868B Beltpack Pack
P 8170
SAVE 29%
A 4154 2x100W
35
$
Protect Your AV System & Cut Power Consumption!
Power, telephone, aerial and satellite dish surge protection. Allows a master appliance (ie
TV) to switch on/off slave appliances automatically, such as receiver, DVD etc. Drastically
cuts standby power usage.
SAVE 15%
Bargain Audio Visual Bits!
225
$
C 0840
P 6895 White
P 6896 Black
Maintenance free
outdoor sound!
BARGAIN!
12.75
$
Waterproof 4” Speakers
With rust free stainless fittings & aluminium grille!
All weather speaker and grill assembly, for long life
even in marine or tropical areas. 20W RMS. 4Ω.
SAVE 22%
35
$
C 0383
Virtually
indestructible!
Redback® Drop Proof Microphone
16 Channel UHF Wireless Mic Systems
A complete wireless mic system with your choice of
handheld or lapel/beltpack mic. • Plugs into
existing PA systems • Crisp vocal reproduction
• Ideal for clubs, restaurants & wedding ceremonies.
Up to 70m range.
49
A 2710
SAVE 12%
79
$
H 8181A
Simply plug in a USB stick, connect the RCA output
to your amplifier & press play! It even automatically
loops. Requires M 9272A 12VDC plugpack $17.95.
Incredibly lightweight
Combo AV Wallplate
Back to back connection, no soldering required. Stereo audio,
component video & HDMI. Fits
a standard electrical wallbox.
SAVE $19
60
$
$
P 6872
Swing Arm LCD Monitor Bracket
Latest
Generation
Dynalink® HDMI Leads
3DTV compatible. Superb quality
for any home theatre system. High
speed HDMI with Ethernet (V1.4).
Lifetime warranty.
Part
RRP
Now...
1.5m
P 6620B
$29.95
$25
3m
P 6622B
$39
$33
5m
P 6624B
$49
$42
10m
P 6626B
$89
$79
15m
P 6628B
$139
$119
Extends up to 335mm from the mounting
surface. Ultra slimline design. 20° ball joint
for tilt adjustment. Suits monitors up to 24”.
100x100mm VESA mount.
SAVE 19%
WAS $99
Compact Speaker
& Lighting Stands
69
Folding portable design is
lightweight & sturdy. Ideal
for use with the Redback
speakers above. Adjustable
1-2m. Max 40kg. Suits
35mm top hats. Flat top
mounting bracket to suit,
C 0522 $11.95.
With
HDMI!
80 Silicon Chip
ONE-STOP ELECTRONICS SHOP
80/pr
40
$
Value 3 Way HDMI Selector
An economical way to switch between
3 HDMI sources. No power required!
Size: 104 x 120 x 26mm.
A 1170
Dynalink® Infra-Red Extender Kit
C 0521A
$
A 3084
$
SAVE 20%
SAVE 20%
39
C 8914
SAVE 18%
$
USB Background Music Player
Buff coloured hands free mic
for lecturers, spruikers etc.
Simply hooks over your ear for
a comfortable fit. Includes
1.2m 3 pin mini XLR lead.
This plate allows cables to pass into the wall
cavity without soldering. Includes curtain to
stop dust/vermin from entering.
Great for restaurants,
cafes and offices
Super tough grill resists damage, even when dropped
onto hard floors. Ideal choice for clubs & schools.
Includes 5m 3 pin XLR lead.
Redback® Skin Tone
Presenters Mic
No Cable Termination Required!
Improves sound
dispersion!
Great for controlling equipment when its
located inside cabinets or entertainment
units. Kit includes hub, IR target, four IR
emitters & power supply. Foxtel compatible
(non IQ only).
Our ‘One-Stop’ Electronic
Enthusiast Centres...
DVI-A to
VGA Adaptor
A handy go-between
for monitors, projectors,
TVs and video
cards.
SAVE 18%
16
$
P 6560
Perth WA: 174 Roe St
Balcatta WA: 7/58 Erindale Rd
Auburn NSW: 15 Short Stsiliconchip.com.au
Springvale VIC: 891 Princes Hwy
Resellers:
39.95
59
$
.95
$
SAVE 20%
SAVE 14%
K 1107
K 1095
Add on a K 1108
USB interface for
control from your
PC - $39.95
Robotic Arm & Claw Kit - No Soldering Required!
3 In 1 All-Terrain Robot Kit
A great introduction to basic robotics - ideal project for students.
Includes five motors allowing base rotation, shoulder, elbow and
wrist motion, plus claw for picking up objects (up to 100g).
Includes wired controller.
Great fun for the kids to build and play with! This single kit
can be built (and re-built) three ways to create a forklift,
all-terrain rover or gripping ‘pick up’ machine. Lifting
capacity ≈100g. Includes wired remote control.
SAVE 12%
Re-assembles
into a new
machine in
an hour!
Enhance
the sound
from your
MP3 player
SAVE 10%
70
$
76
$
K 2572
K 2558
Time
stamps
all data
readings
K 5508
NEW KIT!
59.95
$
Headphone Amplifier Kit
USB Datalogger Kit
(SC Dec ‘10 - Mar ‘11) Based on a PIC
micro, this simple project can log data to
a memory card. It can read from many
types of digital and analog sensors. A realtime clock and calendar “time-stamps”
the data. Includes a PC host program,
allowing you to configure the sensors,
change settings and charge the battery via
USB (2 x AAA, not included).
Capacitor Leakage Meter Kit
(SC Dec ‘09). Performs leakage current
testing on almost any type of capacitor.
A valuable piece of test equipment for
servicing. Seven test voltages from 10-100V.
Leakage current 10mA-100nA. Requires
6xAA batteries.
NEW KIT!
12.95
(SC Feb ‘12) This tiny regulator board
outputs 1.2-20V from a higher voltage DC
supply at currents up to 1.5A. It’s small,
efficient and cheap to build, Features low
drop-out voltage, low heat generation and
electronic shut-down.
SAVE 25%
65
NEW KIT!
Mini Switching Regulator
K 6145
$
$
K 6340
(SC May ‘11) This compact device not only
boosts the volume output of your device, but
significantly improves fidelity - lowering distortion &
noise. Provides up to 200hrs use from 2xAA
batteries (not included)
54.95
$
K 5526
Stereo Audio Compressor
(SC Jan ‘12) Do you hate the way the
sound level on your TV suddenly jumps
during the advert breaks? Or do you find
that the sound levels vary widely when
switching between digital TV stations?
This compressor fixes those problems by
reducing the dynamic range of the signal
while still maintaining clean sound. Also
ideal for use with PA systems. Requires 1230V DC power.
Remote Control Digital Timer Kit
(SC August ‘10) Switch low voltage devices
on/off after set periods. Operated by the
included universal remote control. • Trigger
inputs • DPDT relay output (30VDC/24VAC - not
suitable for mains switching) • Requires
M 9237A 9V plugpack $17.95.
SAVE 15%
75
$
NEW KIT!
29.95
$
K 6042
SAVE 10%
175
Mains Soft Start Kit
(SC April ‘12) Tames those nasty surge
currents when appliance/loads switch on,
preventing breakers from tripping due to
the temporary high load level. This is a
common problem when switching on
multiple switchmode appliances from the
same power circuit. This handy kit limits
inrush current to appliances, without
affecting performance.
$
GPS Boat Computer Kit
K 1143
(SC Oct ‘10) Tells you exactly where you
are - never get lost at sea again. Also shows
speed and heading - plus it will navigate you
back home - or to that secret fishing spot! It
even displays fuel consumption, along with
a host of other vital information.
K 6026
Solar Powered Alarm Kit
(SC March ‘10). A handy security solution for
sheds, boats, caravans and remote buildings.
Coupled with an N 0700 solar panel this alarm
system may be used with up to 3 sensors (eg: reed
switch/pressure mat). Includes PIR movement
sensor & siren.
N 0700 5W solar panel: $29.95
S 5075B 1.3Ah SLA battery: $19.95
B 0092
Sale Ends August 31st 2012
Altronics One-Stop Electronic Shops Phone 1300 797 007 Fax 1300 789 777
siliconchip.com.au
Mail Orders: C/- P.O. Box 8350 Perth Business Centre, W.A. 6849
© Altronics 2012. E&OE. Prices stated herein are only valid for the current month or until stocks run out. All prices include GST and exclude freight and
insurance. See latest catalogue for freight rates. All major credit cards accepted.
WESTERN AUSTRALIA
Bunbury
ML Communications (08) 9721 9800
Esperance
Esperance Communications (08) 9071 3344
Geraldton
ML Communications (08) 9965 7555
VICTORIA
Beaconsfield
Electronic Connections (03) 9768 9420
Benalla
Leading Edge Electronics (03) 5762 2710
Castlemaine
Top End Technology (03) 5472 1700
Clayton
Rockby Electronics (03) 9562 8559
Cranbourne
Bourne Electronics (03) 5996 2755
Croydon
Truscott's Electronic World (03) 9723 3860
Geelong
Music Workshop (03) 5221 5844
Healesville
Amazon DVDs Healesville (03) 5962 2763
Highett
AV2PC (03) 9555 2545
Leongatha
Gardner Electronics (03) 5662 3891
Melton
Melton Electronics & Comms. (03) 9743 1233
Nunawading
Semtronics (03) 9873 3555
Pakenham
Get Smart Hifi (03) 5941 4886
Preston
Preston Electronics (03) 9484 0191
San Remo Shorelec Electrical Wholesalers (03) 5678 5361
Somerville
AV2PC (03) 5978 0007
Stawell
David O Jones Mitre 10 (03) 5358 1205
Thomastown
Digizone (03) 9465 8885
Warnambool
Multicomm IT & Comms. (03) 5561 5111
Wodonga
Exact Computers & Home Ent. (02) 6056 5746
TASMANIA
Hobart
Active Electronics (03) 6231 0111
Launceston
Active Electronics (03) 6334 7333
QUEENSLAND
Brisbane South
Delsound (07) 3397 8155
Brisbane North
Prime Electronics (07) 3252 7466
Cairns
Pentacom (07) 4032 1710
Caloundra
IT Shop (07) 5309 5943
Cloncurry
Access Electronics (07) 4742 2590
Gold Coast
Prime Electronics (07) 5531 2599
Hervey Bay
Ultra Music (07) 4128 2037
Innisfail
Leading Edge Electronics (07) 4061 6214
Longreach
Access Electronics (07) 4658 0500
Rockhampton
Access Electronics (07) 4922 1058
Toowoomba
Michael's Electronics (07) 4632 9990
Townsville
Solex (07) 4771 4211
NEW SOUTH WALES
Brookvale Brookvale Electrical Distributors (02) 9938 4299
Cessnock
Leading Edge Electronics (02) 4990 5971
Cobar
Cobar Electronics (02) 6836 2962
Deniliquin
Wired Entertainment (03) 5881 3555
Gloucester
Autolec Gloucester (02) 6558 1600
Grafton
Downes Electronics (02) 6642 1911
Griffith
Griffith Systems Plus (02) 6964 5933
Gunnedah
Protronics (02) 6742 2110
Lithgow
Leading Edge Electronics (02) 6352 3333
Nth Richmond Candle Power Technologies (02) 4571 4699
Oak Flats
Oak Flats Electronics (02) 4256 6120
Orange
Fordray Electronics (02) 6362 9901
Penrith
Penrith Light and Sound (02) 4733 3333
Port Macquarie
Fettel Communications (02) 6581 1341
Raymond Terrace Leading Edge Electronics (02) 4987 4909
Smithfield
Chantronics (02) 9609 7218
Tamworth
Bourke Street Electronics (02) 6766 4664
Taree
Noeledge Systems Pty Ltd (02) 6551 3622
Wagga Wagga
Wagga Car Radio & Hi-Fi (02) 6925 6111
Waterloo
Herkes Electrical Supplies (02) 9319 3133
Wetherill Park Techtron Electronics Pty Ltd (02) 9604 9710
Windang
Mad Electronics (02) 4297 7373
Wyong
Coastal Caravan and RV Pty Ltd. (02) 4353 1100
SOUTH AUSTRALIA
Adelaide
Aztronics (08) 8212 6212
Brighton
Force Electronics (08) 8377 0512
Enfield
Aztronics (08) 8349 6340
Findon
Force Electronics (08) 8347 1188
Kadina
Idyll Hours Hobbies (08) 8821 2662
Mt Barker
Classic Lights & Electronics (08) 8391 1133
Port Lincoln Milton Leading Edge Electronics (08) 8682 4911
NORTHERN TERRITORY
Darwin
Combined Communications (08) 8942 0644
NEW ZEALAND
Christchurch - Riccarton
Global PC +64 3 3434475
Christchurch - Shirley
Global PC +64 3 3543333
Please Note: A
Resellers
have to2012 81
pay the cost of freight and
ugust
insurance and therefore the range of stocked products & prices
charged by individual resellers may vary from our catalogue.
Pt.3: By JOHN CLARKE
Wideband Oxygen Sensor
Controller Mk.2
In Pt.2 last month, we gave the full assembly details for our new
Wideband Controller Mk.2 and its companion Display Unit.
Our final article this month describes how the oxygen sensor is
installed in a car and connected to the Wideband Controller.
A
S MENTIONED in Pt.1, the Bosch
LSU4.9 wideband sensor can be
installed in the exhaust pipe by screwing it into a suitable threaded boss.
This should be positioned as close to
the engine as possible.
Note, however, that the exhaust gas
temperature under all engine operating conditions at the sensor position
must be less than 780°C otherwise
the sensor may overheat. In general,
installing the wideband sensor in the
same position as the existing narrowband sensor should be OK.
You can check for sensor overheating by monitoring the heater impedance. This is done with jumper JP1
installed. The wideband output as
measured between the tip and sleeve
of a 3.5mm jack plug should normally
be 684mV DC or about ±2% above
and below this. If the Display Unit is
connected (and is set up to measure
82 Silicon Chip
lambda), it should show 0.85 (0.840.86 range).
If the sensor has overheated, the
above-listed voltage or value will
fall significantly. And if it’s severely
overheated, the Wideband Controller
indicating LED will revert to its dim
indication.
An overheating sensor will have
to be relocated to a cooler section of
the exhaust manifold, ie, further from
the engine.
The following points should also be
taken into consideration:
(1) The sensor must not be mounted in
the exhaust manifold of a turbocharged
engine. Instead, it must be installed
after the turbocharger.
(2) The exhaust pipe section prior
to the sensor should not contain any
pockets, projections, protrusions,
edges or flex-tubes etc, to avoid the
accumulation of condensation water.
Locating the sensor on a downward
slope of the pipe is recommended.
(3) The sensor must be mounted perpendicular to the exhaust stream so
that it can constantly monitor fresh
exhaust gas. It must also be mounted
so that it is inclined at least 10° from
horizontal (electrical connection upwards) – see Fig.19. This is necessary
to prevent condensation collecting
between the sensor housing and the
element.
(4) The recommended material to use
for the threaded boss in the exhaust
pipe is temperature-resistant stainless
steel to the following standards: DIN
174401.4301 or 1.4303, SAE 30304 or
30305 (US). Fig.20 shows the threaded
boss dimensions. Note that the sensor
thread must be covered completely.
(5) The use of high-temperature resistant grease on the screw thread of the
boss is recommended. The tightening
siliconchip.com.au
(VERTICAL
PLANE)
Mounting The Oxygen Sensor On The Exhaust
25
10.5 +/-0.35
3
> 10°
23
ALL DIMENSIONS
IN MILLIMETRES
(HORIZONTAL PLANE)
Fig.19: the Bosch wideband sensor must
be fitted to the exhaust pipe at an angle
of at least 10° above horizontal. This is
necessary to ensure that any condensation
drains out of the unit.
torque is from 40-60 Nm.
(6) The sensor must be protected if
an under-sealant such as wax or tar
or spray oil is applied to the vehicle.
(7) The sensor must not be exposed
to strong mechanical shocks (eg, during installation or removal using an
impact driver). If it is, the element
could crack and destroy the sensor
without there being visible damage
to the housing.
(8) Both the sensor and its connecting
cable should be positioned to avoid
damage due to stones or other debris
thrown up by the wheels.
(9) Do not expose the sensor to water
drips from the air-conditioner or from
sources such as windscreen run-off
during rain or when using the windscreen washer. The resulting thermal
stress could damage of the sensor.
(10) Never switch on the sensor heating until the engine starts. This means
that VR2 must be correctly adjusted to
ensure heating does not begin until
after the engine has started, as detected
by a higher battery voltage (see settingup procedure last month).
Using the S-curve output
As mentioned last month, the
S-curve output from the Wideband
Controller can be used to replace the
existing narrowband signal. However,
the vehicle must be currently using
a zirconia-type narrowband oxygen
sensor. If the vehicle already has a
wideband sensor, then this sensor’s
output should not be replaced with
the S-curve signal from the Wideband
Controller.
siliconchip.com.au
A less common type of narrowband
lambda sensor has a ceramic element
made of titanium dioxide. This type
does not generate a voltage but instead
changes its resistance according to the
oxygen concentration. Once again,
this type cannot be simulated using
the S-curve signal from the Wideband
Controller.
Identifying the sensor leads
In order to replace the existing sensor with the S-curve output from the
Wideband Controller, you first need
to identify the leads running from the
sensor to the ECU. Basically, there are
four narrowband sensor variations:
(1) If the sensor has one lead this will
be the signal wire and the sensor body
will be ground.
(2) If the sensor has two leads, one will
be the signal lead and the other will
either be the signal common or (in the
case of a heated sensor) a +12V heater
lead. For a heated sensor, the body
forms a common ground for both the
signal and heater circuits.
(3) A 3-wire sensor usually has Heater+
(H+), Heater- (H-) and sensor signal
leads, with the body as the signal
ground. Alternatively, it could have
a sensor signal lead, a sensor ground
lead and a heater H+ lead, with the
sensor body as heater H-.
(4) A 4-wire sensor is similar to a
3-wire sensor but with ground leads
for both the signal ground and H-.
In each case, the leads are quite easy
to identify but first a word of warning. Do not measure the narrowband
sensor impedance with a multimeter.
TAPPED WITH
M18 x 1.5
THREAD
Fig.20: this diagram shows the
dimensions of the threaded boss
that’s used to attach the sensor. It
must be made of stainless steel and
should cover the sensor’s thread
completely. The tightening torque is
from 40-60 Nm.
The reason for this is that the current
produced by the meter when measuring resistance may damage the sensor.
Note also that the maximum loading for the sensor is 1µA. This means
that to measure the voltage produced
by a narrowband sensor, the meter
must have an input impedance higher
than 1MΩ. Digital multimeters (DMM)
generally have an input impedance
much higher than 1MΩ but an analog
meter may not have the required high
impedance.
The first step in identifying the leads
is to set your DMM to DC volts, then
connect the negative lead of the DMM
to chassis. That done, it’s a matter of
starting the engine and probing the
sensor’s leads with the DMM’s positive lead (a pin can be used to pierce
the wire insulation but seal any holes
with silicone afterwards to prevent
corrosion.). The sensor’s H+ lead will
be at +12V, while its signal voltage lead
will vary but should average over time
at about 450mV.
Once these two leads have been
identified, switch off the engine and
unplug the sensor. The H- terminal
can now be identified – it’s the one
that gives a low resistance reading of
typically 5Ω (and usually less than
10Ω) to the previously identified H+
terminal (warning: do not connect the
meter probe to the previously identified signal terminal when making
resistance measurements).
The signal ground terminal is the
one remaining.
In some cars, the ECU will check
that the sensor is connected and
August 2012 83
How To Remove The Original
Original Narrowband Sensor
W
HEN REPLACING an existing narrowband sensor with the LSU4.9
wideband sensor, make sure you re
move the correct unit. The required
sensor is the one that’s between the
exhaust manifold and the catalytic converter. A second oxygen sensor located
downstream from the catalytic converter
is there to monitor the latter’s operation.
Removing the narrowband sensor
may be difficult if you do not have the
correct tools. The type of tool required
depends on the sensor’s placement.
With limited height access, you may
have to resort to using an open-ended
22mm (or 7/8-inch) spanner. In most
cases, though, you should be able to use
a special oxygen sensor removal tool.
This uses a 22mm socket that has a slit
along one side to allow the oxygen sen-
sor wires to protrude (see photo below).
It’s also common for the original
oxygen sensor to seize in the threaded
boss in the exhaust manifold pipe. As a
result, the nut will refuse to budge and
will simply start to “round off” under
spanner tension. The main difficulty is
that the socket or spanner needs to be
an open-ended type, as a ring spanner
or standard socket will not fit over the
sensor connector. And an open-ended
spanner tends to spread open under
tension.
Even with the correct tool, removing a seized oxygen sensor can be
difficult. In our case, we used “Loctite
Freeze & Release Lubricant” (Part No.
FAR IDH1024403) to help free it. This
“shock cools”, penetrates and lubricates
the screw threads and this allowed us
This special oxygen sensor removal tool allows the sensor’s leads to exit via
a slot in the side of the socket. Make sure that the sensor leads turn with the
sensor as it is undone.
produce an error code if it detects
that anything is amiss. In most cases,
however, the S-curve signal from the
Wideband Controller will be accepted
as valid but there are exceptions.
First, the ECU may check the sensor’s impedance to determine if it is
sufficiently heated (ie, when its impedance falls below a particular value).
However, the impedance the ECU will
measure at the Wideband Controller’s
S-curve output will be 150Ω and this
may be incorrect for some sensors.
This means that the 150Ω output
resistor may have to be changed in
84 Silicon Chip
some cases, to prevent an error code
from the ECU.
Heater fault indications
Some ECUs will also indicate a fault
if the heater leads to the oxygen sensor are disconnected. In that case, you
will have to keep the original heater
connections to the old sensor and
mount it in a convenient place away
from parts that could melt (eg, against
the firewall). Just make sure that the
heated sensor cannot be accidentally
touched, as it can run very hot.
Alternatively, you can make up a
to eventually loosen and remove the
sensor.
If you are not concerned about damaging the original sensor, its connector
can be cut off so that a ring spanner can
be slipped over it and onto the hexagonal
nut. This can then be “tapped” with a
hammer in the anticlockwise direction
to loosen the sensor. Note, however,
that this method will probably crack the
ceramic material inside the sensor, leaving it permanently damaged.
Which ever method is used, Freeze
and Release Lubricant is still recommended because it makes removal
much easier. It also helps prevent the
sensor nut from being rounded off, which
would then make removal extremely
difficult.
Note that special high-temperature
grease should be used on the screw
threads if you refit the existing sensor.
That way, it will be easy to remove next
time. A new sensor (such as the Bosch
LSU4.9 sensor) will be supplied with this
grease already applied to the thread.
resistance box that has the same nominal resistance as the sensor’s heater
element when hot. The hot resistance
will be higher than the cold resistance
and can be measured by disconnecting
the sensor lead immediately after the
engine has reached operating temperature and then measuring the heater
resistance using a DMM.
The alternative resistors should go
in a diecast case and must be rated for
to handle the power dissipation. In
practice, the power rating is calculated
by assuming a 14.8V maximum supply
and a 50% derating. For example, if
the heater hot resistance is 12Ω, then
14.8V2 ÷ 12Ω = 18.25W.
In practice, a 40W resistor would be
required and so the heater resistance
could be simulated by connecting four
47Ω 10W resistors in parallel.
Because the Wideband Controller’s
S-curve output needs to simulate the
original narrowband sensor, it’s a good
idea to check the operation of the
original narrowband sensor when the
car is running. This can be done using
a multimeter and an oscilloscope to
monitor the sensor’s output. Alternatively, an OBD (On-Board Diagnostics)
scan tool that shows live or real-time
parameter data can be used to monisiliconchip.com.au
Mounting The O 2 Sensor In A Tailpipe Extension
EXHAUST TAILPIPE
SENSOR
CLAMP FOR
ATTACHING TO
EXHAUST PIPE
Fig.21: follow this diagram
to build a tailpipe sensor
unit if you don’t want a
permanent installation.
MOUNTING
BOSS
EXHAUST
OUT
EXHAUST FLOW
150
ALL DIMENSIONS
IN MILLIMETRES
I
f you do not wish to install the wideband O2 sensor permanently, an
alternative is to mount it in a tailpipe
extension. This tailpipe extension
can then be slid over the end of the
tailpipe and clamped in position –
see Fig.21.
Note, however, that any readings
obtained using this method will be
affected by the catalytic converter
and so won’t be as accurate. That’s
because the catalytic converter
reacts with the exhaust gas and
changes the oxygen content. In
addition, some catalytic converters
include an air-bleed to feed oxygen
tor the sensor voltage, if this feature is
supported on your vehicle.
When the engine is warm and idling,
the sensor reading should oscillate
above and below 450mV at a rate
dependent on the sensor’s response
rate and the ECU. By using the oscilloscope, the frequency of oscillation and
the voltage can be directly measured (a
multimeter will probably not respond
quickly enough to show the full cyclic
voltage range).
A typical narrowband sensor response is shown in Fig.22.
Connecting the controller
The Wideband Controller must be
connected to the vehicle’s 12V supply.
The two ground wires are connected
to chassis (adjacent to the lead from
battery’s negative terminal), while
the positive lead connects to the ignisiliconchip.com.au
100
250mm LENGTH OF
38mm (1.5") PIPE
into the exhaust to allow full catalytic
operation with rich gases. This won’t
be a problem in older cars that don’t
have a catalytic converter.
Note that when the sensor is
fitted to a tailpipe extension, TP2
in the Wideband Controller can be
set for 4V. This will ensure that the
sensor heater is immediately powered when the Wideband Controller
is powered, without having to wait
until the battery voltage rises when
the engine is started (note: we
don’t have to wait in this situation
because condensation is no longer
a problem).
tion supply. Make sure this supply
remains at +12V while the engine is
started as some switched ignition supplies (eg, for the sound system) are disconnected during engine starting.
Next, replace the existing narrowband sensor with the wideband sensor, then connect the S-curve output
from the Wideband Controller to the
sensor+ signal input of the ECU. That
done, check that TP2 in the Wideband
Controller has been adjusted to 4.33V
to ensure that the engine is must be
started before the sensor is heated (see
setting-up procedure last month).
To do this, first switch on the ignition without starting the engine and
check that the LED on the controller
is only dimly lit. This indicates that
sensor heating has not yet started.
Conversely, if the LED lights brightly,
it indicates that the sensor is heating
After use, make sure that the
sensor is stored upright in a dry
environment, to prevent moisture
forming in the unit.
Fig.21 should be followed quite
closely if you intend mounting the
sensor in a tailpipe extension. By
using the dimensions shown, the
sampled exhaust gas is taken sufficiently upstream from the end of
the tailpipe to prevent dilution with
outside air.
The pipe and clamp materials can
be made of steel or brass but use
a stainless-steel boss for mounting
the sensor.
and so VR2 will need to be adjusted
to give a higher voltage at TP2.
In practice, you may have to experiment to get the best setting for VR2 (as
measured at TP2). If TP2 is too low in
voltage, sensor heating will start before
the engine starts. Conversely, if TP2 is
too high, sensor heating will not start
immediately after engine-starting and
will not kick in until the battery voltage rises sufficiently. You can confirm
this by revving the engine a little until
the battery voltage rises high enough
to start the sensor heating.
Note that you will need to switch off
the Wideband Controller via the ignition and then back on again to have
any changes to the TP2 voltage read
by the controller. That’s because this
voltage is only checked at power-up,
so always switch the controller off and
on again each time you adjust VR2.
August 2012 85
Using A Wideband Sensor In A Permanent Installation
A
S A TEST, we installed a wideband
sensor in place of the original narrowband sensor in a 2004 Holden Astra.
The S-curve output from the Wideband
Controller was then fed to the car’s ECU
(in place of the output from the original
sensor).
This worked well, with no error codes
produced by the ECU provided that
the heater connections to the original
narrowband sensor remained in place.
In operation, the narrowband signal
from the Wideband Controller enabled
the engine fuel mixture to cycle correctly
The correct setting for VR2 is critical
to prevent sensor damage. Basically,
it prevents the sensor from heating
before the engine exhaust has blown
out any condensation.
Note, however, that condensation
only occurs after the sensor has cooled.
If the Wideband Controller starts heating the sensor when it is already warm
but before the engine has started, then
that’s OK. In practice, this means that
VR2 should be set when the battery is
at its normal resting voltage – ie, after
the engine has been off for some time.
For example, the battery voltage may
be above 13V when the engine has just
been switched off, but it will eventually drop to below 13V.
Once VR2 has been correctly adjusted, start the engine and monitor the
S-curve output. It should cycle above
and below 450mV in a similar manner
to the original narrowband sensor.
If the S-curve simulation proves unsuccessful, either because the engine
runs poorly or the ECU logs a fault
code, then the narrowband sensor will
have to be reinstalled. The Wideband
above and below the stoichiometric
value. In short, it proved to be compatible and the Holden Astra’s engine ran
normally.
This is in marked contrast to the Wideband Controller described in September
and October 2009. With that controller,
the overall response to the air/fuel mixture was too slow compared to that from
the original narrowband sensor.
As a result, the engine RPM constantly varied at a fixed throttle setting
as the air/fuel ratio varied above and
below stoichiometric. This in turn varied
Sensor will then have to be installed in
a separate position. Often, fault codes
can be cleared by disconnecting the
vehicle’s battery for a minute or so.
Otherwise an engine-code reader will
be required to clear the fault.
Note that disconnecting the battery
may affect a security-coded sound system on some older cars, which means
that and the security code will have
to be re-entered. Disconnecting the
battery or clearing a fault code using
an engine-code reader could also reset
some of the learned parameters stored
in the car’s ECU. These parameters
include such things as engine timing
(to prevent pinging) and fuel-mixture
trim. These are tabled values made
by the ECU during normal operation
to improve engine running and fuel
economy based on oxygen sensor readings and knock sensing. As a result,
the engine may take a while to restore
these parameters if they are cleared.
Pressure connections
If you wish to monitor the exhaust
pressure, it will be necessary to drill
0.55V
TIME
0.45V
0.35V
1.25sec
Fig.22: a typical narrowband sensor response when the engine is warm and
idling. The output oscillates above and below 450mV as the ECU maintains
a stoichiometric mixture.
86 Silicon Chip
the vehicle’s road speed at constant
throttle settings. As a result, the original
Wideband Controller Mk.1 was unsuccessful as a permanent installation, at
least in the Holden Astra.
By contrast, our new Wideband
Controller Mk.2 using the LSU4.9 sensor produces a much lower range of
RPM cycling at constant throttle above
idle and with no load (transmission in
Neutral). In fact, it’s no more than occurs
with the original narrowband sensor in
place and is completely unnoticeable
when the vehicle is being driven.
a small hole through the exhaust pipe
and then braze a short length of metal
tubing (steel or brass) to the pipe near
the sensor. This should be located on
the downstream side, so that it doesn’t
provide a condensation point above
the sensor.
The tube length should be such that
the exhaust pipe heat is dissipated sufficiently for the rubber pressure tubing
to attach without burning.
If you don’t wish to monitor the
pressure, just leave the port open
(or leave the pressure sensor out and
install the links as described in Pt.2).
Wideband controller tests
If you strike problems with your
Wideband Controller, the best way
to troubleshoot it is to first alter it to
measure the oxygen content in air.
That way, you can check the operating
voltages in the circuit while the sensor
monitors a known “mixture”.
The necessary changes to the circuit
are as follows:
Step 1: Disconnect the sensor and
add a 560kΩ resistor in parallel with
the 560kΩ resistor between pins 6 &
7 of IC3b. You can use TP7 and TP6
to terminate the leads of this resistor.
Step 2: Add a 560kΩ resistor in parallel
with the 560kΩ resistor between pin
5 of IC3b and the Vs/Ip connection.
You can use test points TP1 and TP5
to terminate the leads.
Step 3: Remove the 510Ω resistor in
series with the 62kΩ resistor for the
20µA reference current and install
another 62kΩ resistor in its place (ie,
so that the total resistance between Vs
and the +5V rail is 124kΩ).
Step 4: Apply power and adjust VR3
siliconchip.com.au
so that Vs/Ip is at 2V, as measured
between TP1 and TP GND.
Step 5: Adjust VR4 so that TP4 is
2.343V.
Having made these changes, you
can now troubleshoot the Wideband
Controller as follows:
Step 6: Gently rest the sensor in a Pyrex
bowl, connect it to the controller and
apply power.
Step 7: Wait until the sensor has
heated and the indicator LED flashes
at a fast rate. Now check the various
operating voltages on the circuit. The
voltage between Vs/Ip (or TP1) and Vs
should be 450mV. The voltage between
TP11 and TP GND should be 2.5V.
However, there may be small variations from these values as the controller continually adjusts the current to
maintain these voltages.
Step 8: If you have an oscilloscope,
check that the 684mV p-p square-wave
(used for sensor impedance measurement) is present at TP11. Alternatively,
by inserting jumper JP1, the wideband
output (as measured between the
sleeve and tip connections of a stereo
3.5mm jack plug) will indicate the
impedance of the sensor instead.
This should show 684mV DC for
the sensor impedance to be kept at
300Ω. This may vary by ±2% or so as
the controller maintains temperature,
due to the resolution of the impedance measurement. Alternatively, if
you have the Wideband Display unit
connected (and set to show lambda), it
should show a reading of 0.85 or 0.86.
Step 9: Check that TP12 (or TP7) is
at 4V (ie, the Vs/Ip voltage of 2V plus
the amplified voltage across the 62Ω
resistor between Rcal & Ip). To explain,
the Ip current through the 62Ω resistor
should be 2.54mA when measuring
20.9% oxygen (ie, the oxygen content
of air), so there should be 157.5mV
across this resistor. IC3b operates with
a gain of 12.73 (560kΩ//560kΩ ÷ 22kΩ),
so this adds an extra 2V to the Vs/Ip
voltage at TP12 to give a total of 4V.
Step 10: Check that the wideband output (between tip and sleeve) is at 2V
with JP1 out. The Wideband Display
should show 1.15 (if set to display
lambda).
Note that if the air pressure is less
than 1013hPa due to atmospheric
conditions or altitude, the readings
specified above may differ slightly.
However, if VR3 has been correctly
adjusted for altitude as detailed in Step
4 above, the error will be corrected.
siliconchip.com.au
This photo shows an original
narrowband sensor at left and
the Bosch LSU4.9 wideband
sensor at right. The original
sensor has exhaust gas entry
slots in the side to provide
faster exhaust gas access
compared to the access at the
base of the LSU4.9 sensor.
This OBDII diagnostic tool readout shows how the simulated narrowband
(S-curve) output cycles about stoichiometric when the Bosch LSU4.9 wideband
sensor and the Wideband Controller were installed on a 2004 Holden Astra.
The horizontal scale is 10 seconds. The blurriness is due to display update
movement as the trace moves leftward.
Resistor tolerances will also cause
the voltage reading to differ. If necessary, the unit can be calibrated to
give an exact 2V wideband output
by changing the 62Ω resistor. To this
end, the PCB has extra mounting holes
so that a multi-turn 100Ω trimpot
can be fitted instead. However, this
modification shouldn’t be necessary.
Configuring the controller to measure
the oxygen content in air is done to
test the circuit’s operation rather than
check the sensor calibration.
Step 11: Once all checks are complete,
restore the circuit to normal operation by undoing the changes outlined
in Steps 1-3 above – ie, remove JP1,
remove the two extra 560kΩ resistors
and replace the added 62kΩ resistor
with the 510Ω resistor. That done,
disconnect the sensor, apply power to
the Wideband Controller and readjust
VR3 to give 3.3V at VS/Ip and VR4 to
SC
give 3.92V at TP4.
August 2012 87
Vintage Radio
By Rodney Champness, VK3UG
The Philips BX373A
4-valve receiver
The set with the “Bibber Schaal” (shaky dial scale)
Until now, Vintage Radio has concentrated
almost exclusively on Australian-made
receivers. This month, however, we’re going
to take a look at a Dutch receiver, the Philips
BX373A 4-valve table/mantel receiver from
1948. It’s an excellent performer although the
design is different to Australian sets.
T
HIS PARTICULAR Philips BX373
receiver is owned by John de Haas
who has a fine collection of vintage
radios, many of them originating from
Holland (see SILICON CHIP, June 2012).
And although it’s a 4-valve set, the
BX373A’s performance rivals that of
many 5-valve receivers. It operates
on both the broadcast and shortwave
bands, as well as the long-wave band.
As shown in the photos, the receiver
is housed in a large, polished Bakelite
88 Silicon Chip
cabinet with an interesting circular
dial to the right. The On-Off/Volume
control is towards the centre-bottom
at the front of the cabinet, while the
Tuning control is to the right. The
Wave-Change switch is accessed at the
righthand end of the cabinet, while the
Tone control is at the opposite end.
The receiver is no lightweight and
weighs a substantial 6kg. It’s also quite
large at 44 x 19 x 25cm (W x D x H),
including the knobs. At that size, it
could be considered to be either a table
set or a mantel set.
The dial scale is unusual but attractive. It’s also interesting in that it
doesn’t indicate the frequency being
tuned but instead shows the approximate wavelength. I personally feel uncomfortable with this and prefer some
indication of the tuned frequency.
As well as the wavelength indications, the dial-scale also carries corresponding country and city markings
around the perimeter. The centre of the
dial has three symbols which indicate
how the Wave-Change knob should be
set to select a particular band.
The back of the set is covered by
a thin wooden panel with numerous
ventilation holes. This panel carries a
number of graphics which indicate the
functions of the various sockets which
are accessible through large clearance holes. These graphics not only
helped people who were unfamiliar
with radio terminology but also meant
that the same panel could be used on
sets exported to non-Dutch speaking
countries.
Dismantling the receiver
Removing the chassis from the cabinet is straightforward. The first step
is to remove the control knobs which
are all push-on types. The four screws
holding the rear panel in place are
then removed, after which the screw
holding the tone control’s Bakelite
shaft in place is loosened. Once that’s
done, this shaft can then be removed.
However, you have to be careful doing this as this Bakelite shaft is easily
broken. And while it’s possible to get
a replacement from one enterprising
enthusiast, it will set you back around
$50!
Next, the four screws that go through
the rubber buffers on the bottom of the
cabinet must be removed, followed by
the two screws that secure the front of
the chassis to the inside front of the
cabinet. These latter two screws are
recessed several centimetres into the
siliconchip.com.au
This is the view inside from the rear of the cabinet. The loudspeaker is fully enclosed
in a cloth “sock”, to keep dust and small insects away from the cone.
cabinet, so you will need a special
screwdriver for this job, especially
when it comes to later reinstalling
them.
In my case, I use a small screwdriver
with spring-loaded clamps to hold the
screw in place on the blade. Alternatively, if you don’t have this type of
screwdriver, a small amount of BluTack or Kwik Grip on the screw head
can be used to hold it in place while
it is installed.
Once all the screws have been
removed, the chassis can be slid out
through the back. The only component
left behind is the speaker, which is
attached to the inside front of the
cabinet.
First impressions
A quick examination of the chassis
reveals a few initial surprises. It also
has a few things that are different from
Australian sets.
First, for some strange reason, the
rectifier socket is mounted proud of
the chassis instead of flush-mounted.
It almost looks as though the designers forgot that they needed space for a
rectifier when the chassis layout was
being decided on.
In addition, as with many other
European sets, the power transformer
and the associated wiring to it are not
as well-protected against accidental
contact compared to Australian designed sets. On the other hand, once
in the cabinet and with the rear panel
fitted, this European receiver is just as
safe as an Australian set.
One unusual feature is that the
speaker is fully enclosed in a cloth
“sock”, to keep dust and small insects
away from the cone. This helps ensure
that the speaker cone stays in good
condition and contributes to the long
life of the speaker.
Another unusual feature is the tun-
The parts on the top of the chassis are all easy
to access, so servicing is straightforward.
siliconchip.com.au
August 2012 89
Fig.1: the circuit is a fairly conventional 4-valve superhet design. Note that the detected audio from valve B3 is fed
back to the grid of the triode section in valve B2. This signal is then amplified by B2 and fed to the grid of B3 which
further amplifies the signal and drives the loudspeaker via an output transformer.
Under the chassis, the multi-band
tuning and switching arrangement is
very compact and servicing this part
of the circuit would be awkward. It
would also make alignment adjustments a little more difficult than usual.
Circuit details
Did the designers forget to leave space
for the rectifier when they designed
the chassis? For some strange reason,
it’s mounted proud of the chassis
instead of sitting down flush.
ing capacitor mounting arrangement.
If you touch the tuning capacitor, you
immediately discover that it is on a
very flexible mounting. As a result, it
wobbles around quite a bit more than
usual, hence the set’s Dutch nickname
of “Bibber Schaal”, which roughly
translates to “Shaky Scale”.
It make me wonder just how stable
the tuning is on shortwave if the set
is given a bump!
90 Silicon Chip
Take a look now at Fig.1 for the circuit details. It’s a fairly conventional
superhet design with four valves,
including the rectifier.
The first thing to note is that although there is provision for an external antenna, a “plate” antenna is also
provided for those who consider an
antenna a nuisance. This plate antenna
consists of foil plate glued to the inside
of the back panel and this is attached
to the antenna input in parallel with a
lead from the external antenna terminal. In strong signal areas, a plate-type
antenna will work quite well but an
outside antenna will provide the best
performance.
The front-end is typical of that used
in many European sets. It’s a triple-band
design with long-wave (150-420kHz),
medium-wave (517-1620kHz) and
shortwave (5.9-18.75MHz) tuning capabilities. In Australia, the long-wave
band was used for only a very short
time when public radio broadcasts first
started in the 1920s. These days, the
band is used for navigational beacons
which send out tone-modulated Morse
code identification or computer spoken
weather reports for aircraft.
The 3-band antenna and oscillator
tuned circuits are selected as required
by the band-switch. As shown, the antenna terminal is connected to a seriestuned circuit consisting of coil S5 and
C6. These are tuned to the 452kHz
IF (intermediate frequency) and this
minimises signal breakthrough from
stations at the high-frequency end of
the long-wave band. This is necessary because these stations operate at
frequencies close to the IF (down to a
minimum of just 32kHz away).
The tuned input signal is applied
to the signal grid (grid one) of the
heptode section of valve B1, an ECH21
triode-heptode converter. The oscillator signal is applied to grid three, so
that the incoming signal is converted
to the 452kHz IF.
The selected output signal on
452kHz is taken from the anode and
applied to the heptode section of valve
B2, another ECH21, via a doubletuned IF transformer (in this case,
the triode section is not connected to
the heptode). The amplified signal is
then fed via a second double-tuned
IF transformer to valve B3, an EBL21
duo-diode power output pentode.
siliconchip.com.au
As an aside, AWV in Australia later
developed the 6BV7, a 9-pin miniature
valve with similar characteristics to
the EBL21. It wasn’t as reliable as the
EBL21, however.
Getting back to Fig.1, the detector
diode in B3 is fed from a tap on the
secondary of the IF transformer. The
detected audio signal is then fed back
to the grid of the triode section of valve
B2 where it is amplified and applied
to the grid of B3. B3 in turn drives
the speaker transformer and the set’s
internal speaker.
There is also provision for an extension speaker and this can be plugged
in via a socket on the back panel. Note
that negative feedback from the speaker’s voice coil is routed back via R21
and the tone control switch (shown
just above valve B3 on the circuit).
Pick-up inputs
The rear panel also provides access
to a pair of pick-up inputs, so that
records can be played back via the
audio amplifier stages of the receiver.
To prevent interference from the
front-end stages, the output from the
detector is open-circuited when the
pick-up lead is plugged into the rearpanel socket (see top of circuit). The
RF and IF stages of the receiver remain
fully operational, however.
In practice, this means that if the
set just happens to be tuned to a very
strong station, some leakage of the
detected audio signal would almost
certainly occur across the pick-up
The ventilated panel at the rear of the set carries graphics which indicate the
functions of the various sockets. As well as antenna and earth terminals, the set
has pick-up input terminals and an external loudspeaker output socket.
socket. That, in turn, would result in
a weak radio signal audibly interfering
with the signal from the record player.
Rendering the front-end of the receiver inoperative by removing the HT
to some or all of that section would
have completely eliminated this problem. However, simply tuning off the
station may also have been enough to
prevent interference.
Power supply
The power supply is conventional
and includes a power transformer
with six primary tappings to cater for
mains voltages ranging from 110VAC
to 245VAC. The secondary has three
windings: a 4V winding for the rectifier
heater, a 6.3V winding for the other
valve heaters and a centre-tapped HT
(high-tension) winding. The two outer
leads of this HT winding go to the
anodes of rectifier valve B4.
B4 is an AZ1, which is a duo-diode
rectifier. Its HT output is fed though
a winding on the audio output transformer and this not only provides ripple filtering but also bucks any hum
which may be present on the grids of
the audio amplifier stages.
Despite the set’s age, the chassis was
in excellent condition and very little
work was required to restore it to full
working order.
siliconchip.com.au
August 2012 91
is fed via R15 to B1 and B2 to ensure
correct operation before AGC voltage
is applied.
This bias voltage is also fed to the
AGC diode in B3, while a sample of
the detected audio signal is derived
from the primary of the second IF
transformer and also fed to the AGC
diode. As a result, a strong signal will
quickly equal or exceed the negative
bias (applied via R15) on the AGC
diode, to control the gain of the frontend stages.
Summary
The dial-scale on the Philips BX373A is rather unusual, with wavelength rather
than frequency indications. In addition, the perimeter carries various European
country and city markings.
This close-up view shows the band-switching assembly. The compact layout
makes it awkward to service and align correctly.
The set’s power consumption is
around 45W, which is about average
for this type of set.
Delayed AGC
As shown on Fig.1, a back-bias network is connected across the centretap of the secondary winding on the
power transformer. This network
provides bias for valve B3 (EBL21) and
92 Silicon Chip
for the triode section in B2 (ECH21), as
well as providing a delayed automatic
gain control (AGC) voltage source for
both B1 and B2.
Valve B3 has two detector diodes
inside its envelope. One is used as
the detector, while the other is used to
provide delayed AGC. In this case, a
standing bias of about -2V is obtained
from the junction of R19 and R20. This
Despite being only a 4-valve set, the
Philips BX373A is effectively equivalent to a 5-valve set and performs accordingly. The valves used are ones
not commonly used in Australia and
they also have base layouts which
were not much used here either. In
fact, the valves can be considered to
be high-performance units and this
set was designed to a high standard
for the time (around 1948).
One area of criticism is that this set
has controls which emerge through the
sides of the cabinet – in this case, the
wave-change switch at one end and
the tone control at the other. The tone
control in particular is very poorly
thought out and it shouldn’t have been
all that difficult for it to have been
fitted to the front skirt of the chassis.
Of course, the BX373A is not alone
in placing some controls like this and
some designs even have controls at the
back of the set as well.
John has the original service manual
for the set and although it’s printed
in Dutch, it’s still quite easy to understand most of the information in
it. This includes the dial-stringing
arrangement, which is rather unique
(to put it mildly) due to the very flexible dial drive and tuning capacitor
mounting. It certainly deserves the
“Shaky Scale” nickname.
Other useful diagrams show the
wiring layout for both the top and
underside of the chassis.
In summary, the Philips BX373A
is a well-designed set that performs
extremely well and looks very appealing. It didn’t require a large number
of parts for John to restore it good
working condition, which indicates
that Philips used good quality parts
during manufacture.
This is one of John’s favourite receivers and it makes a fine addition
SC
to a collection.
siliconchip.com.au
STIC
FANTAIDEA
GIFT UDENTS
FOR SFT ALL
O S!
AGE
THEAMATEUR SCIENTIST
An incredible CD with over 1000 classic projects
from the pages of Scientific American,
covering every field of science...
THE LATEST
VERSION 4 –
WITH EVEN
MORE
FEATURES!
Arguably THE most IMPORTANT collection
of scientific projects ever put together!
This is version 4, Super Science Fair Edition
from the pages of Scientific American.
As well as specific project material, the CD
contains hints and tips by experienced amateur
scientists, details on building
science apparatus, a large
database of chemicals and
so much more.
ONLY
62
$
00
PLUS $10 Pack and Post
within Australia
NZ P&P: $AU12.00,
Elsewhere: $AU18.00
“A must for every science student,
science teacher, science lab . . . or simply
for those with an enquiring mind . . .”
Just a tiny selection of the incredible range of projects:
Build a seismograph to study earthquakes Make soap bubbles that last for
months Monitor the health of local streams Preserve biological specimens
Build a carbon dioxide laser Grow bacteria cultures safely at home Build a
ripple tank to study wave phenomena Discover how plants grow in low gravity
Do strange experiments with sound Use a hot wire to study the crystal structure
of steel Extract and purify DNA in your kitchen Create a laser hologram Study
variable stars like a pro Investigate vortexes in water Cultivate slime moulds
Study the flight efficiency of soaring birds How to make an Electret Construct
fluid lenses Raise butterflies as experimental animals Study the physics of
spinning tops Build an apparatus for studying chaotic systems Detect metals in
air, liquids, or solids Photograph an ant's brain and nervous system Use
magnets to make fluids into solids Measure the metabolism of an insect . . .
and many, many more (a thousand more, in fact!)
See the V2 review in SILICON CHIP, October 2004. . . or read on line at siliconchip.com.au
This is the ALL-NEW Version 4 . . . it’s even BETTER!
HERE’S HOW TO ORDER YOUR COPY:
BY PHONE:*
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There’s also a handy order form inside this issue.
Exclusive in SILICON
Australia to: CHIP siliconchip.com.au
siliconchip.com.au
August 2012 93
SILICON
CHIP
PARTSHOP
Looking for a specialised component to build that latest and greatest SILICON CHIP project? Maybe it’s the PCB you’re after.
Or a pre-programmed micro. Or some other hard-to-get “bit”. The chances are they are available direct from the SILICON CHIP PARTSHOP.
As a service to readers, SILICON CHIP has established the PARTSHOP. No, we’re not going into opposition with your normal suppliers
– this is a direct response to requests from readers who have found difficulty in obtaining specialised parts such as PCBs & micros.
• PCBs are normally IN STOCK and ready for despatch when that month’s magazine goes on sale (you don’t have to wait for them to be made!).
• Even if stock runs out (eg, for high demand), in most cases there will be no longer than a two-week wait.
• One low p&p charge: $10 per order, regardless of how many boards or micros you order! (Australia only; overseas clients – email us for a postage quote).
• Our PCBs are beautifully made, very high quality fibreglass boards with pre-tinned tracks, silk screen overlays and where applicable, solder masks.
• Best of all, those boards with fancy cut-outs or edges are already cut out to the SILICON CHIP specifications – no messy blade work required!
PRINTED CIRCUIT BOARD TO SUIT PROJECT:
PUBLISHED:
CODE:
Price:
PRINTED CIRCUIT BOARD TO SUIT PROJECT:
PUBLISHED:
CODE:
Price:
AM RADIO TRANSMITTER
JAN 1993
06112921
$25.00
100W DC-DC CONVERTER
MAY 2011
11105111
$25.00
CHAMP: SINGLE CHIP AUDIO AMPLIFIER
FEB 1994
01102941
$5.00
PHONE LINE POLARITY CHECKER
MAY 2011
12105111
$10.00
PRECHAMP: 2-TRANSISTOR PREAMPLIER
JUL 1994
01107941
$5.00
20A 12/24V DC MOTOR SPEED CONTROLLER MK2
JUNE 2011
11106111
$25.00
HEAT CONTROLLER
JULY 1998
10307981
$25.00
USB STEREO RECORD/PLAYBACK
JUNE 2011
07106111
$25.00
MINIMITTER FM STEREO TRANSMITTER
APR 2001
06104011
$25.00
VERSATIMER/SWITCH
JUNE 2011
19106111
$25.00
MICROMITTER FM STEREO TRANSMITTER
DEC 2002
06112021
$10.00
USB BREAKOUT BOX
JUNE 2011
04106111
$10.00
SMART SLAVE FLASH TRIGGER
JUL 2003
13107031
$10.00
ULTRA-LD MK3 200W AMP MODULE
JULY 2011
01107111
$25.00
12AX7 VALVE AUDIO PREAMPLIFIER
NOV 2003
01111031
$25.00
PORTABLE LIGHTNING DETECTOR
JULY 2011
04107111
$25.00
POOR MAN’S METAL LOCATOR
MAY 2004
04105041
$10.00
RUDDER INDICATOR FOR POWER BOATS (4 PCBs)
JULY 2011
20107111-4
$80 per set
BALANCED MICROPHONE PREAMP
AUG 2004
01108041
$25.00
VOX
JULY 2011
01207111
$25.00
LITTLE JIM AM TRANSMITTER
JAN 2006
06101062
$25.00
ELECTRONIC STETHOSCOPE
AUG 2011
01108111
$25.00
POCKET TENS UNIT
JAN 2006
11101061
$25.00
DIGITAL SPIRIT LEVEL/INCLINOMETER
AUG 2011
04108111
$15.00
STUDIO SERIES RC MODULE
APRIL 2006
01104061
$25.00
ULTRASONIC WATER TANK METER
SEP 2011
04109111
$25.00
ULTRASONIC EAVESDROPPER
AUG 2006
01208061
$25.00
ULTRA-LD MK2 AMPLIFIER UPGRADE
SEP 2011
01209111
$5.00
RIAA PREAMPLIFIER
AUG 2006
01108061
$25.00
ULTRA-LD MK3 AMPLIFIER POWER SUPPLY
SEP 2011
01109111
$25.00
GPS FREQUENCY REFERENCE (A) (IMPROVED)
MAR 2007
04103073
$55.00
HIFI STEREO HEADPHONE AMPLIFIER
SEP 2011
01309111
$45.00
GPS FREQUENCY REFERENCE DISPLAY (B)
MAR 2007
04103072
$30.00
GPS FREQUENCY REFERENCE (IMPROVED)
SEP 2011
04103073
$55.00
KNOCK DETECTOR
JUNE 2007
05106071
$25.00
DIGITAL LIGHTING CONTROLLER LED SLAVE
OCT 2011
16110111
$30.00
SPEAKER PROTECTION AND MUTING MODULE
JULY 2007
01207071
$25.00
USB MIDIMATE
OCT 2011
23110111
$30.00
CDI MODULE SMALL PETROL MOTORS
MAY 2008
05105081
$15.00
QUIZZICAL QUIZ GAME
OCT 2011
08110111
$30.00
LED/LAMP FLASHER
SEP 2008
11009081
$10.00
ULTRA-LD MK3 PREAMP & REMOTE VOL CONTROL
NOV 2011
01111111
$35.00
12V SPEED CONTROLLER/DIMMER (Use Hot Wire Cutter PCB from Dec2010 18112101)
$25.00
ULTRA-LD MK3 INPUT SWITCHING MODUL
NOV 2011
01111112
$25.00
CAR SCROLLING DISPLAY
DEC 2008
05101092
$25.00
ULTRA-LD MK3 SWITCH MODULE
NOV 2011
01111113
$10.00
USB-SENSING MAINS POWER SWITCH
JAN 2009
10101091
$45.00
ZENER DIODE TESTER
NOV 2011
04111111
$20.00
DIGITAL AUDIO MILLIVOLTMETER
MAR 2009
04103091
$35.00
MINIMAXIMITE
NOV 2011
07111111
$10.00
INTELLIGENT REMOTE-CONTROLLED DIMMER
APR 2009
10104091
$10.00
ADJUSTABLE REGULATED POWER SUPPLY
DEC 2011
18112111
$5.00
INPUT ATTENUATOR FOR DIG. AUDIO M’VOLTMETER
MAY 2009
04205091
$10.00
DIGITAL AUDIO DELAY
DEC 2011
01212111
$30.00
6-DIGIT GPS CLOCK
MAY 2009
04105091
$35.00
DIGITAL AUDIO DELAY FRONT & REAR PANELS
DEC 2011
0121211P2/3 $20 per set
6-DIGIT GPS CLOCK DRIVER
JUNE 2009
07106091
$25.00
AM RADIO
JAN 2012
06101121
$10.00
UHF ROLLING CODE TX
AUG 2009
15008091
$10.00
STEREO AUDIO COMPRESSOR
JAN 2012
01201121
$30.00
UHF ROLLING CODE RECEIVER
AUG 2009
15008092
$45.00
STEREO AUDIO COMPRESSOR FRONT & REAR PANELS
JAN 2012
0120112P1/2 $20.00
6-DIGIT GPS CLOCK AUTODIM ADD-ON
SEPT 2009
04208091
$10.00
3-INPUT AUDIO SELECTOR (SET OF 2 BOARDS)
JAN 2012
01101121/2
$30 per set
STEREO DAC BALANCED OUTPUT BOARD
JAN 2010
01101101
$25.00
CRYSTAL DAC
FEB 2012
01102121
$20.00
DIGITAL INSULATION METER
JUN 2010
04106101
$25.00
SWITCHING REGULATOR
FEB 2012
18102121
$5.00
ELECTROLYTIC CAPACITOR REFORMER
AUG 2010
04108101
$55.00
SEMTEST LOWER BOARD
MAR 2012
04103121
$40.00
ULTRASONIC ANTI-FOULING FOR BOATS
SEP 2010
04109101
$25.00
SEMTEST UPPER BOARD
MAR 2012
04103122
$40.00
HEARING LOOP RECEIVER
SEP 2010
01209101
$25.00
SEMTEST FRONT PANEL
MAR 2012
04103123
$75.00
S/PDIF/COAX TO TOSLINK CONVERTER
OCT 2010
01210101
$10.00
INTERPLANETARY VOICE
MAR 2012
08102121
$10.00
TOSLINK TO S/PDIF/COAX CONVERTER
OCT 2010
01210102
$10.00
12/24V 3-STAGE MPPT SOLAR CHARGER REV.A
MAR 2012
14102112
$20.00
DIGITAL LIGHTING CONTROLLER SLAVE UNIT
OCT 2010
16110102
$45.00
SOFT START SUPPRESSOR
APR 2012
10104121
$10.00
HEARING LOOP TESTER/LEVEL METER
NOV 2010
01111101
$25.00
RESISTANCE DECADE BOX
APR 2012
04105121
$20.00
UNIVERSAL USB DATA LOGGER
DEC 2010
04112101
$25.00
RESISTANCE DECADE BOX PANEL/LID
APR 2012
04105122
$20.00
HOT WIRE CUTTER CONTROLLER
DEC 2010
18112101
$25.00
1.5kW INDUCTION MOTOR SPEED CONTROLLER
APR 2012
10105121
$35.00
433MHZ SNIFFER
JAN 2011
06101111
$10.00
HIGH TEMPERATURE THERMOMETER MAIN PCB
MAY 2012
21105121
$30.00
CRANIAL ELECTRICAL STIMULATION
JAN 2011
99101111
$30.00
HIGH TEMPERATURE THERMOMETER F&R PANELS
MAY 2012
21105122/3
$20 per set
HEARING LOOP SIGNAL CONDITIONER
JAN 2011
01101111
$30.00
MIX-IT! 4 CHANNEL MIXER
JUNE 2012
01106121
$20.00
LED DAZZLER
FEB 2011
16102111
$25.00
PIC/AVR PROGRAMMING ADAPTOR BOARD
JUNE 2012
24105121
$30.00
12/24V 3-STAGE MPPT SOLAR CHARGER
FEB 2011
14102111
$15.00
CRAZY CRICKET/FREAKY FROG
JUNE 2012
08109121
$10.00
SIMPLE CHEAP 433MHZ LOCATOR
FEB 2011
06102111
$5.00
CAPACITANCE DECADE BOX
JULY 2012
04106121
$20.00
THE MAXIMITE
MAR 2011
06103111
$25.00
CAPACITANCE DECADE BOX PANEL/LID
JULY 2012
04106122
$20.00
UNIVERSAL VOLTAGE REGULATOR
MAR 2011
18103111
$15.00
WIDEBAND OXYGEN CONTROLLER MK2
JULY 2012
05106121
$20.00
12V 20-120W SOLAR PANEL SIMULATOR
MAR 2011
04103111
$25.00
WIDEBAND OXYGEN CONTROLLER MK2 DISPLAY BOARD
JULY 2012
05106122
$10.00
MICROPHONE NECK LOOP COUPLER
MAR 2011
01209101
$25.00
SOFT STARTER FOR POWER TOOLS
JULY 2012
10107121
$10.00
PORTABLE STEREO HEADPHONE AMP
APRIL 2011
01104111
$25.00
DRIVEWAY SENTRY MK2
AUG 2012
03107121
$20.00
CHEAP 100V SPEAKER/LINE CHECKER
APRIL 2011
04104111
$25.00
MAINS TIMER
AUG 2012
10108121
$10.00
PROJECTOR SPEED CONTROLLER
APRIL 2011
13104111
$10.00
CURRENT ADAPTOR FOR SCOPES AND DMMS
AUG 2012
04108121
$20.00
SPORTSYNC AUDIO DELAY
MAY 2011
01105111
$30.00
AND NOW THE PRE-PROGRAMMED MICROS, TOO!
Some micros from copyrighted and/or
contributed projects may not be available.
As a service to readers, SILICON CHIP is now stocking microcontrollers and microprocessors used in new projects (from 2012 on) and some
selected older projects – pre-programmed and ready to fly! Price for any of these micros is just $15.00 each + $10 p&p per order#
PIC12F675
PIC16F1507-I/P
PIC16F88-E/P
PIC16F877A-I/P
PIC18F2550-I/SP
PIC18F4550-I/P
PIC18F14K50
PIC18F27J53-I/SP
UHF Remote Switch (Jan09), Ultrasonic Cleaner (Aug10),
Ultrasonic Anti-fouling (Sep10), Cricket/Frog (Jun12)
Wideband Oxygen Sensor (Jun-Jul12)
Projector Speed (Apr11), Vox (Jun11), Ultrasonic Water Tank
6-Digit GPS Clock (May-Jun09), Lab Digital Pot (Jul10)
Semtest (Feb-May12)
Batt Capacity Meter (Jun09), Intelligent Fan Controller (Jul10)
GPS Car Computer (Jan10), GPS Boat Computer (Oct10)
USB MIDIMate (Oct11)
USB Data Logger (Dec10-Feb11)
Digital Spirit Level (Aug11), G-Force Meter (Nov11)
Intelligent Dimmer (Apr09)
Maximite (Mar11), miniMaximite (Nov11)
Digital Audio Signal Generator (Mar-May10), Digital Lighting Controller
(Oct-Dec10), SportSync (May11), Digital Audio Delay (Dec11)
Level (Sep11), Quizzical (Oct11), Ultra-LD Preamp (Nov11)
dsPIC33FJ64MC802-E/SP Induction Motor Speed Controller (Apr-May12)
ATTiny861
VVA Thermometer/Thermostat (Mar10), Rudder Position Indicator (Jul11)
ATTiny2313
Remote-Controlled Timer (Aug10)
ATMega48
Stereo DAC (Sep-Nov09)
PIC18LF14K22
PIC18F1320-I/SO
PIC32MX795F512H-80I/PT
dsPIC33FJ128GP802-I/SP
When ordering, be sure to nominate BOTH the micro required and the project for which it must be programmed.
Other items currently in the PartShop:
P&P – $10 Per order within Australia.
G-FORCE METER/ACCELEROMETER SHORT FORM KIT
AUG 2011/NOV 2011
$44.50
(contains PCB (04108111), programmed PIC micro, MMA8451Q accelerometer chip and 4 MOSFETS)
RADIO & HOBBIES ON DVD-ROM (Needs PC to play!)
n/a
AMATEUR SCIENTIST VOL4 ON CD
n/a
$62.00
$62.00
TENDA USB/SD AUDIO PLAYBACK MODULE (TD896 or 898)
JAN 2012
$33.00
JST CONNECTOR LEAD 3-WAY
JAN 2012
$4.50
JST CONNECTOR LEAD 2-WAY
JAN 2012
$3.45
Prices include GST and are valid only for month of publication of these lists; thereafter are subject to change without notice. *Note: P&P is extra ($10 per order in Australia).
# Orders may be for mixed items (eg, you can order one PCB, or one microprocessor, or three PCBs and two microprocessors – and the P&P on any of these orders is $10.00
08 /12
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08/12
ASK SILICON CHIP
Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line
and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097 or
send an email to silicon<at>siliconchip.com.au
How to select
resettable fuses
I have a question related to resettable fuses. These devices have a “holding current” which is a safe current
through the device and also a “trip
current”, the point at which the device
interrupts the current flow.
For example, the MF-R300 has a
holding current of 3A and a trip current of 6A. What I’m confused about is
what happens when the current is, say,
4.5A? I am guessing the fuse wouldn’t
trip at 4.5A but would it eventually trip
if that current is maintained?
Furthermore, the data sheet at http://
www.farnell.com/datasheets/90504.
pdf, under the “typical time to trip”
section, states that the MF-R300 will
trip after a second at 20A. This seems
very high seeing that earlier in the data
sheet it says the trip current is 6A.
Can you inform me on the correct
way to select a resettable fuse? Let’s say
my device under normal conditions
can draw anywhere from 0-3A. Any
more than about 3A is not normal and
a fault may be present.
How would I go about determining
what resettable fuse I’d need? (B. W.,
via email).
• Fuse rating for holding and trip current are based on time. The MF-R300
fuse is designed to stay closed at the
holding current for at least 30 minutes
(1800s). It will trip before five times
that period (ie, 2.5 hours). In other
words, the MF-R300 will trip at 3A
between 30 minutes and 2.5 hours.
According to the graph in the data,
the fuse will trip at 6A after about
1000s. At higher currents it will trip
more quickly. The data table shows
that it will trip at 15A within 10.8
seconds.
So the holding current is the current
that the fuse will trip (eventually) but
at higher currents it will trip faster.
So if your device does not draw a
continuous 3A, then the MF-R300
will be suitable. If it does draw 3A
on a continuous basis, then the MFR400 (4A) might be better to prevent
nuisance tripping.
Setting the delay
on a VOX circuit
I have been looking for a VOX relay
that could switch on a very small amplifier when it receives an audio signal
(for example, from an Apple Airport
Express) and would subsequently turn
off a couple of minutes after the signal
disappears, ie, so it doesn’t turn off
between tracks.
Through the wonders of Google,
I stumbled on the VOX circuit published in July 2011. Will this project
be suitable? Where can I buy a kit or
the components? (M. P., via email).
• The VOX from July 2011 should be
suitable for your application. Time-out
is a maximum of 10 seconds but this
could be increased to a longer period
using a 470µF capacitor at the cathode
of diode D4 instead of the 100µF value.
There is no kit available but the PCB,
code 01207111, can be obtained from
SILICON CHIP for $25. Contact pcbs<at>
siliconchip.com.au
The components are available from
Jaycar and Altronics: www.jaycar.
com.au and www.altronics.com.au
Using the VOX
for PA work
The VOX article in the July 2011 issue of SILICON CHIP is stated to be suitable for PA systems or amateur radio
use. However, I believe that the circuit
has an omission which precludes its
use for these purposes. It does not have
any means of extracting the audio from
the microphone to then use it for the
PA or amateur transceiver.
A small addition to this circuit
would enable this to be done. Any
ideas for a modified VOX to be able to
control the relay and allow the audio
Browns Gas Is A Fraud
I have been reading SILICON CHIP
since its inception. It keeps the mind
up with the tech times. My friend is
running his car on a mixture of HHO.
I have been following this subject for
years. As someone said, “I wish those
calling this a joke would stop pestering those doing it”.
I have just been and seen a small
Briggs and Stratton engine running on
pure HHO (water). Being an experiment, the metering was wrong and
after a few minutes it blew the head
gasket. I would love to see more on
this subject especially for generators
that run constant speeds.
96 Silicon Chip
So far people are tinkering with
dozens of configurations. We need
topics from SILICON CHIP on EFIEs,
pulse circuits to play with and get
Australia ahead of the world that is
now marketing this subject in welders
and fuel alternatives.
Considering that Browns Gas is an
Australia patent, let’s get behind him.
(M. R., via email).
• Brown’s gas is not an Australian
patent. It is a load of rubbish. Why is
there still any interest in this topic?
There was a Publisher’s Letter on this
topic in the November 2008 issue and
a detailed answer on the topic in the
“Ask SILICON CHIP” section on pages
89 & 90 of the September 2008 issue.
We hesitate to even mention the
topic again because a whole new
cohort of gullible people with no
knowledge of science will want
to jump on the band-wagon again.
Doesn’t the fact that the small engine
in your demonstration blew up cast
any doubt on the whole concept?
If you really want the background
on this topic, ignore everything you
might have read on the internet and
refer to the articles above. That should
end all interest but sadly, we know
it won’t.
siliconchip.com.au
to be used as well? (C. M., via email).
• Typically, a signal is taken or
tapped off from the transceiver or
public address (PA) system to obtain
a signal to trigger the VOX. Since we
are not breaking the signal to the transceiver or PA but just tapping it off, the
transceiver or PA unit will still have
an audio signal. There is no need to
tap the signal from the VOX itself for
the PA or transceiver.
An electret microphone is usually
connected when the VOX is used for
a stand-alone sound activated switch
rather than when used with a transceiver or PA.
However, tapping the signal from
the VOX is possible using either the
3.5mm jack socket or the screw terminals. These essentially provide a
signal in and loop out (as a parallel
connection). If you require an amplified signal, the pin 1 output of op amp
IC1a can be used provided it is fed via
a capacitor to block the DC level.
Mains isolation
switch required
Due to weather and other influences,
we lose the power grid from time to
time. I then drag out my 2.3kW generator to supply my fridge, lights and TV.
So there are power leads all over the
place; most untidy.
I would like to have my distribution
board modified so that I could cut off
the grid altogether and then plug in
and run my generator until the power
comes back up. How should I go about
doing this? (S. S., via email).
• The best way to arrange this is to
have an electrician install an isolating
switch or solenoid. That way, all your
household or selected circuits can be
powered from your generator when
needed. You can even leave the generator permanently connected, ready to
be switched over at any time.
Trying the SoftStarter
with an inverter (1)
With reference to the SoftStarter
project in the April 2012 issue, can
this device be used to run an 385W
water pump motor from a 12V to 230V
inverter (pure sinewave)?
When used directly, the high start
winding current trips the inverter
cut-out. I understand that the starting current is up to 10 times the run
current. By using the SoftStarter will
siliconchip.com.au
Powering PIC Microcontrollers
I am currently designing a circuit
that drives two printer stepper motors and a few PIC microcontrollers
for a CNC machine. I have a 15V
power supply. I am planing to use
a simple resistive divider to divide
the voltage to 5V for the PIC chips
and drive the steppers through an
L293D H-bridge and with the chips
in parallel. Is this correct or are there
better ways to set up the circuit? (V.
K., via email).
• You can use a voltage divider to
get the 5V rail for the microcontrollers but it’s generally not a good idea
for a few reasons. First, the resulting
voltage will track the 15V supply
and that may vary substantially depending on the supply itself, what
the motors are doing, etc.
Also, because the microcontrollers are in parallel with the bottom
leg of the divider and they have a
variable impedance, the resulting
voltage will be lower than you would
expect and will vary depending
on what they are doing (sleeping,
idling, running etc).
That means you would need to use
quite low value resistors, to ensure
sufficient current to swamp these
this decrease the high initial burst of
current and also allow the motor to
start and run normally?
I am attempting to run my water
pump from solar-powered batteries.
(L. S., via email).
• Presumably, you want the pump
motor to start repeatedly, ie, each time
you turn on a tap. This means that the
April 2012 design is not suitable. You
need the later design featured in the
July 2012 issue – see the answer below.
Trying the SoftStarter
with an inverter (2)
Could you please tell me if either of
the SoftStarter projects, ie, from the
April or July 2012 editions, would be
suitable to reduce the start-up current
of a chest freezer, potentially enabling
the freezer to be run in a remote location using a lower-power inverter, eg,
300W to 600W? (P. B., via email).
• A typical chest freezer needs about
200W continuous power when the
compressor is running so a 300-600W
inverter should be OK once it has
effects and that wastes power.
The next best solution is to replace
the bottom resistor in the divider
with a zener diode or a shunt regulator. That virtually eliminates variations in supply voltage with load
impedance but that configuration
still wastes quite a bit of power (usually at least 10mA to ensure correct
zener operation).
We suggest using a linear regulator like the 78L05 instead. They are
quite cheap (under a dollar from
most suppliers), only draw 3mA and
provide near-perfect regulation but
should have a capacitor connected
across the input and output (10µF is
sufficient). With a 15V supply, you
can draw about 50mA from the 5V
output. For more current, you can
put a resistor in series with the input,
sized to drop about 7V at maximum
load. Above 100mA, use a 7805T.
You certainly can connect multiple microcontrollers or L293D
H-bridge ICs in parallel. It’s always
a good idea to connect a 100nF capacitor between the supply pins of
each device, as close as possible, to
overcome supply track/wire resistance and inductance.
started. The SoftStarter may solve the
issue of the compressor start-up current causing the inverter to trip off but
we’re not sure because there are three
potential problems:
(1) It may limit the in-rush current so
much that the compressor fails to start
until the relay clicks in, at which point
the inverter would be subjected to the
full in-rush current and likely trip off.
(2) It may not limit the in-rush current
enough and the inverter may trip off
anyway.
(3) The Soft Start delay may be too
short and the inverter could trip off
once the relay clicks in.
You can potentially solve problem
(3) by increasing the delay, which can
be done by substituting a larger time
delay capacitor.
All we can suggest is to try it and see
if it works. The Soft Starter for Power
Tools from July 2012 would be the
one to use since you need it to autoreset once the freezer temperature has
dropped far enough for the compressor
to turn off. Otherwise, the inverter will
trip next time it turns on again.
August 2012 97
12V AC Pump Driver Circuit Wanted
I have been a subscriber for many
years and I have searched through
my piles of journals for a circuit to
drive a low-voltage AC pond pump
from a solar panel, without success.
I have in mind the 12V AC synchronous motors which are magnetically coupled to a small impeller
and totally submersed. They usually
draw around 10-20W and are very
reliable over time with continuous use compared with a small DC
pump. It need not run continually
and if the panel has sufficient capacity, the battery could still be charging
when the pump runs.
For example, 50W panels are
now very cheap and should have
enough overhead to charge a 12V
SLA battery which then drives a
small inverter circuit. The circuit
could incorporate a timer and battery cut-out.
Incidentally, I have been running
a large 3-phase lathe and a 3-phase
medium size turret mill in my workshop with a single 2.5kW Variable
13.8V soft-start
circuit wanted
I am looking for a circuit to soft-start
13.8V circuits. Years ago, I had such
a circuit (from Electronics Australia
– RIP) that I used to control driving
lights on a rally car. I would like to
do the same again but can no longer
find it. I wonder if you have or will be
describing a 13V Soft Start system? (S.
C., Aloha, Oregon, USA).
• The 12/24V 20A Motor Speed Controller from the June 2011 issue can
be used to soft-start. When power is
applied (and if the soft start selection
jumper LK1 is inserted), the PWM will
increase over time up to the setting
provided by the speed pot. The speed
pot can be set to maximum if the full
voltage is required after soft start.
Using the Frequency
Switch as a rev limiter
I have purchased your Frequency
Switch project and would like to use it
as a rev limiter on my car which would
cut the ignition, as the standard one
cuts the fuel supply and is not good for
98 Silicon Chip
Frequency Drive, 240V single phase
in, 240V 3-phase out. I was lucky
in that both motors were 6-wire so
they could be rewired, however the
switch gear, power feeds and coolant
pumps have to be wired separately
to the variable frequency supply.
Commonly, these motors run off
110VAC via an auto-transformer
picking off one of the phases. Any
relays are 24V, again off the transformer, so care has to be taken with
this aspect of any conversion; a point
not mentioned in any of the recent
articles on the Induction Motor
Speed Control. You cannot expect to
plug your 3-phase machine into the
converter and have it run properly
without some extra wiring. Great
magazine! (S. S., via email).
• We published the exact circuit
to drive a 12V AC pump as a Circuit Notebook item in the March
2009 issue, entitled “Solar-powered
Fountain Driver”. It was based on
a PIC12F675 and had four Mosfets
to drive the pump in bridge mode.
my engine at high RPM. I was wondering how you would configure the unit
and wire this into my vehicle. There
has been talk on forums about needing
an immobiliser unit from SILICON CHIP
that is to be used with the switch. (B.
F., via email).
• The Frequency Switch can be set
up to switch the relay at a preset RPM.
It should be connected to monitor the
tachometer signal. The relay can be
used to shunt the coil drive.
In other words, the common (C) and
normally open (NO) relay contacts are
connected across the ignition coil transistor (usually to the coil negative and
chassis). This will work if you have
a single coil and distributor but you
need to be sure the coil can withstand
this extra connection time across the
12V supply while rev limiting of the
engine is taking place.
For cars with separate coils for each
cylinder, this approach does not work.
And you cannot disconnect power to
the coils as this will produce a rogue
spark that could damage the engine.
In this case, the only approach is to
throttle back the fuel injectors. This is
best done in small steps rather than
abruptly stopping the fuel. A “Shift
Indicator and Rev Limiter” using that
approach was published in the February 2008 issue.
We are not sure why you say that the
standard rev limiter already installed
in your vehicle that simply cuts the
fuel is not good for the engine. Cutting
fuel will prevent backfire (compared to
ignition cut out) and the limiting action should limit the engine RPM fast
enough so that the engine is not starved
of fuel for cylinder cooling for a long
period. The lack of firing without fuel
will prevent heat rise anyway.
How to program
dsPIC33 micros
Can the PIC Programmer (SILICON
CHIP, May 2008) program the dsPIC33
series, particularly the 28-pin device used in the SD Sound Recorder
(August 2009)? I want to make some
software changes. The programmer
does not seem to have a compiler to
produce hex files. Is one available? (A.
A., Canberra, ACT).
• The May 2008 PIC Programmer can
not program the dsPIC33 series without modifications because they require
a different supply voltage (3.3V rather
than 5V) as well as a capacitor from
the “Vcore” pin to ground.
You could possibly modify that
programmer to work with dsPIC33s
but you may be better off buying a
PICkit3 (less than $50, available at
Element14, for example) and then
just wiring a 5-pin header to the SD
sound recorder PCB with some flying
leads. A small piece of Veroboard can
be used to do this.
A better approach may be to build
the PIC/AVR Programming Adaptor
Board (May & June 2012). This can
program dsPIC33s and many other
PICs. It works in conjunction with the
aforementioned PICkit3.
Compilers for PICs are available
from Microchip (www.microchip.
com) with a free trial period.
Upgrading the switch
in an electric kettle
Would you be interested in a project
for improving reliability of an electric
kettle? It is essentially a simplified
Triac light dimmer circuit which is
controlled by the kettle switch. The
kettle switch should last much longer
because it is no longer switching
siliconchip.com.au
230VAC and 8A. (V. V., via email).
• This is an interesting idea to extend
the switch life but there isn’t any easy
way to remove the Triac heat (about
8W) in such a confined space. The
main power switch usually is switched
off by an in-built thermostat when the
water boils.
Probably most kettle switch failures
would be due to steam and moisture
causing corrosion in the switch mechanism and contacts. This could well be
more of a problem if the main switch
is used as a low-current switch for a
Triac, whereby there will be no contact
cleaning by the normally heavy load
current.
Troubleshooting The G-Force Meter
I built the G-Force Meter (SILICON
CHIP, November 2011) and when I
turned it on for the first time, the
LEDS flashed and then there was
nothing. I get 3V at the source and
at the chip too and I get 3V across
all the pins of the PIC. Any ideas?
(S. S., via email).
• If you are getting 3V at all pins
of the PIC, that suggests you have
a break somewhere in the negative
lead of the battery or on one of the
ground tracks of the PCB. It’s also
possible that the chip isn’t making
good contact with the socket at the
ground pin.
The upper-right pin of the PIC18
Converting beer slabs
to frozen slabs
A customer of mine built the Temp
master thermostat in order to control
the temperature of a beer freezer. However, he returned shortly afterwards
saying that it only has a range of 2°C
to 19°C. It turned out he wanted to
achieve a range of around -10°C to
-18°C with it.
After looking at the circuit, I figured
out how to increase the range (change
the 500Ω pot to 1kΩ) but I’m stumped
as to how I would decrease the lower
limit of the thermostat. Any help
would be much appreciated. (T. M.,
Newcastle, NSW).
• It sounds like your customer wants
to make beer ice blocks! Anyway,
there’s no problem in modifying the
Tempmaster Mk.2 to cover the temperature range he wants. You don’t
even have to change the value of
trimpot VR1; it can stay at 500Ω. All
you need to do is replace the 3.3kΩ
resistor in series with the trimpot with
a resistor of 2.7kΩ. This will shift the
sensing range from -23°C (with VR1
at minimum resistance) to -2°C (with
VR1 at maximum resistance). As you
can see, this is wider than the range
he wants.
However, simply setting the Tempmaster to a temperature setting within
the range of -10°C to -18°C won’t
necessarily make his “beer freezer”
lower the temperature that far. If the
LF13K22 (pin 20) is connected to
ground. This track runs via the
ICSP header (pin 3), along the top
of the PCB to the left, through Q1’s
pad, then down around the edge of
the PCB and to the battery negative
pad. Check that you have continuity between the battery negative
terminal and pin 20 of the PIC.
If you are getting 0V at pin 20 of
IC1 (the expected voltage) and all
the other pins are at 3V, there may
be a fault with the PIC chip itself. If
you programmed the chip yourself,
use your programmer to check that
it’s still functional and to verify it
has the correct program loaded.
freezer’s compressor/chiller unit is
not capable of cooling the beer down
to that temperature, all that will happen is that the Tempmaster will keep
the compressor running continuously.
Bigger shed light
project wanted
I’m considering building the SolarPowered Shed Light project from the
May & June 2010 issues but I have two
important questions to ask.
The first concerns whether the
control circuit includes a low-battery
switching function to cut off the lights
should the state of the battery drop
Radio, Television & Hobbies: the COMPLETE archive on DVD
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August 2012 99
Powering a WW2 Gyro-Compass
Some time ago I purchased a
second-hand WW2 gyro-compass.
With the help of some war museum
staff, I have obtained enough information to indicate that it operates on
3-phase, 115V phase-to-phase, deltaconnected (my estimate is less than
100mA) at 400Hz. Can the Induction
Motor Speed Controller featured in
the April & May 2012 issues be modified to provide these requirements?
Maybe a much simpler circuit would
apply as the frequency and voltage
can be fixed.
There is also a technical complication in that one phase must
be earthed. If the circuit cannot
allow for this, then I would feed it
through an isolating transformer of
which a suggested design would be
appreciated.
I suggest that such a circuit would
be of interest to many museum staff
who at present are operating such
below 11.5V, say. I’ve examined the
circuit in detail and read all the articles
but there appears to be no mention of
this important feature.
Without such a cut-out, lights operating unattended (eg, garden lighting)
could exhaust the battery after a few
winter days of poor sunlight and ruin
the battery. The PIC would be quite
capable of monitoring the battery
voltage during the night and, if it gets
too low, saving the battery by cutting
off the drive to the switching Mosfet.
My second question refers to fitting a larger panel and battery to the
controller to improve the performance
and increase the lighting capacity. I
estimate the controller should be able
instruments on old rotary converters
(if they are available). Rotary converters were the source of power for
many of the instruments in aircraft.
(D. C., via email).
• It would not be a simple matter
to reconfigure the Speed Controller
for 400Hz 115V operation. As well
as new software, there would need
to be a 3-phase output transformer,
since we don’t think 115V devices
would tolerate the 300V peak output
waveform, even if they could cope
with the switching waveforms. We
have no expertise on aviation power,
so don’t know if one phase is earthed
or if there is a neutral. If either of
these is true, then the transformer
is absolutely mandatory.
There are commercial power
supplies that would be suitable but
would be expensive. See for example: http://www.unitronlp.com/
labprodtestpwrsupp.htm
to cope with at least a 20W panel and
two 12V 7Ah SLA batteries without
causing problems for the circuitry,
except perhaps for the MPPT charge
controller.
Such an upgrade would result in
a far better project overall by greatly
increasing the range of applications. I
would be interested in your reply. (B.
T., Churchill, Vic).
• There is a low battery switch-off for
the lamp at 11V, measured when under
lamp load. This is mentioned on the
first page of the article at the end of the
section entitled “Types of Lighting”
and it is in the specifications panel.
The main restriction when it comes
to using a 20W panel is that the
heatsinking for Q1 may need to be
improved. The 470µF 35V low-ESR
capacitors should also be replaced
with either two 470µF 35V low-ESR
capacitors in parallel or by a 1000µF
25V low-ESR capacitor.
Sources for switched
capacitor filter ICs
Reader response 1: In the April 2012
issue, there was a query in the “Ask
SILICON CHIP” section about obtaining
a MF4CN-50 switched capacitor filter
IC, which you noted was obsolete. I
want to point out that these chips are
available on eBay from a US supplier
for $4.00 + postage. (G. M., via email).
Reader response 2: I was reading
a letter from R.W. about sourcing a
switched capacitor filter (MF4CN-50)
in the April edition and a possible
source may be from eBay.
A quick search yielded a supplier in
the USA. This specific seller has 100%
positive feedback with a feedback
score of 9123 and has 50 parts in stock
costing $A3.88 per item and $A3.39
shipping (+10c for every additional
item). I find eBay to be a great source
of components and I have never been
disappointed. (A. H., via email).
Erratic behaviour
from light box
I recently constructed the Light
Box Control Timer unit described in
the November 2007 issue. The unit
is intended to update the old 1980’s
vintage 555-based process timer on
my existing UV light-box that consists
of two Phillips TL-D 18W BLB blacklight/blue fluoro tubes wired in series
with a 40W ballast and 22W starters
etc. All the internals of the light-box
continued on page 104
WARNING!
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projects should be considered dangerous or even lethal if not used safely.
Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When
working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages
or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages,
you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should
anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine.
Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability
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100 Silicon Chip
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SELF ON AUDIO
by Douglas Self 2nd Edition 2006 $69.00
PROGRAMMING and CUSTOMIZING THE
PICAXE By David Lincoln (2nd Ed, 2011) $65.00
See
Review
A great aid when wrestling with applications for the PICAXE
series of microcontrollers, at beginner, intermediate and advanced April
2011
levels. Every electronics class, school and library should have a copy,
A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every
point without significantly increasing cost. Includes compressors/limiters,
hybrid bipolar/FET amps, electronic switching and more. 474 pages in paperback.
along with anyone who works with PICAXEs. 300 pages in paperback
SMALL SIGNAL AUDIO DESIGN
By Douglas Self – First Edition 2010 $88.00
PIC IN PRACTICE
The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio
designers, superb background for audio enthusiasts and especially where it comes to
component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly
recommended. 558 pages in paperback.
by D W Smith. 2nd Edition - published 2006 $60.00
Based on popular short courses on the PIC, for professionals, students and
teachers. Can be used at a variety of levels. An ideal introduction to the world
of microcontrollers. 255 pages in paperback.
AUDIO POWER AMPLIFIER DESIGN HANDBOOK
PIC MICROCONTROLLER – your personal introduc-
by Douglas Self – 5th Edition 2009 $81.00
tory course By John Morton 3rd edition 2005. $60.00
"The Bible" on audio power amplifiers. Many revisions and
updates to the previous edition and now has an extra three
chapters covering Class XD, Power Amp Input Systems and
Input Processing and Auxiliarly Subsystems. Not cheap and not a book
for the beginner but if you want the best reference on Audio Power Amps,
you want this one! 463 pages in paperback.
A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students,
teachers, technicians and electronics enthusiasts. Revised 3rd edition
focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and
12F675. 226 pages in paperback.
PRACTICAL GUIDE TO SATELLITE TV
OP AMPS FOR EVERYONE
By Garry Cratt – Latest (7th) Edition 2008 $49.00
By Carter & Mancini – 3RD EDITION $100.00
Written in Australia, for Australian conditions by one of Australia's foremost
satellite TV experts. If there is anything you wanted to know about setting
up a satellite TV system, (including what you can't do!) it's sure to be covered in this
176-page paperback book.
Substantially updates coverage for low-speed and high-speed applications,
and provides step-by-step walk-throughs for design and selection of op
amps. Huge 648 pages!
PROGRAMMING 32-bit MICROCONTROLLERS
IN C By Luci di Jasio (2008) $79.00
NEWNES GUIDE TO TV & VIDEO TECHNOLOGY
By KF Ibrahim 4th Edition (Published 2007) $49.00
Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful
PIC! Focuses on examples and exercises that show how to solve common,
real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes
source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback.
It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is
ideal for students but covers in-depth technologies such as Blu-ray, DLP,
Digital TV, etc so is also perfect for engineers. 600+ pages in paperback.
USING UBUNTU LINUX
RF CIRCUIT DESIGN
by J Rolfe & A Edney – published 2007 $27.00
by Chris Bowick, Second Edition, 2008. $63.00
Ubuntu Linux is a free and easy-to-use operating system, a viable alternative to Windows and Mac OS. Introduces Ubuntu, tells how to set it up,
covers the various Open Office applications and gives troubleshooting
hints and tips. Highly recommended. 222 pages in paperback
DVD PLAYERS AND DRIVES
by K.F. Ibrahim. Published 2003. $71.00
A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal
for engineers, technicians, students of consumer electronics
and sales and installation staff. 319 pages in paperback.
The classic RF circuit design book. RF circuit design is now more important
that ever in the wireless world. In most of the wireless devices that we use
there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback.
PRACTICAL RF HANDBOOK
See
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Feb
2004
by Ian Hickman. 4th edition 2006 $61.00
A guide to RF design for engineers, technicians, students and enthusiasts.
Covers key topics in RF: analog design principles, transmission lines,
couplers, transformers, amplifiers, oscillators, modulation, transmitters
and receivers, propagation and antennas. 279 pages in paperback.
ELECTRIC MOTORS AND DRIVES
PRACTICAL VARIABLE SPEED DRIVES &
POWER ELECTRONICS
Se
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Intended for non-specialist users of electric motors and drives,
filling the gap between academic texts and general "handbooks".
Explores all of the widely-used modern types of motor and drive
including conventional & brushless DC, induction motors, steppers, servos, synchronous and reluctance. 384 pages, soft cover.
e
Review
Feb
An essential reference for engineers and anyone who wishes
2003
to design or use variable speed drives for induction motors.
by Malcolm Barnes. 1st Ed, Feb 2003. $73.00
286 pages in soft cover.
BUILD YOUR OWN ELECTRIC MOTORCYCLE
AC MACHINES
by Carl Vogel. Published 2009. $40.00
By Jim Lowe Published 2006 $66.00
Applicable to Australian trades-level courses including NE10 AC Machines,
NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control
and Protection. Covering polyphase induction motors, single-phase motors,
synchronous machines and polyphase motor starting. 160 pages in paperback.
Alternative fuel expert Carl Vogel gives you a hands-on guide with
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scooter to a full-sized motorcycle. 384 pages in soft cover.
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August 2012 103
Advertising Index
Altronics.................................. 78-81
Amateur Scientist CD................... 93
Electronex...................................... 9
Embedded Logic Solutions.......... 32
Emona Instruments...................... 71
Geoff Coppa............................... 103
Grantronics................................. 103
Harbuch Electronics....................... 7
Ask SILICON CHIP
. . . continued from p100
are new, having been replaced within
the past few months.
The Light Box Control Timer unit
was a faithful replication of that
described in SILICON CHIP and when
completed performed exactly as described in the article when operated
on the bench with no load attached to
the relay. However, when installed in
the light-box with a fluorescent tube
load connected, it began to behave
somewhat erratically on start-up. Most
of the time it would only generate a
mere flicker from the tubes and then
nothing. Pressing start again usually
had the same outcome, although once
in about five times, before the microprocessor became completely confused and displayed random outputs,
the lamps would fire and run for their
timed period before switching off.
Trying to improve the reliability
of the start-up has proven frustrating
and I have double-checked, tested and
virtually rebuilt the controller board
in several different configurations to
try to isolate and remove the problem,
including re-programming the microprocessor. The differing configurations
included alternative relays (on and off
the PCB), separate input mains power
supplies, full suppression of the mains
input supply etc.
After extended deliberations, I have
concluded after testing the relay with
both DC loads and other AC loads that
the trigger action of the fluorescent
starters seems somehow to be applying a power spike into the input circuitry of the 16F84A, shutting down
operation almost immediately after it
begins, suggesting that some further
decoupling of the micro inputs may
104 Silicon Chip
DOWNLOAD OUR CATALOG at
Hare & Forbes.......................... OBC
www.iinet.net.au/~worcom
Instant PCBs.............................. 103
WORLDWIDE ELECTRONIC COMPONENTS
PO Box 631, Hillarys, WA 6923
Ph: (08) 9307 7305 Fax: (08) 9307 7309
Email: worcom<at>iinet.net.au
Jaycar .............................. IFC,49-56
Notes & Errata
LED Sales.................................. 103
Mix-it! 4-Channel Mixer, June
2012: Fig.8 on page 67 should
show the top switch connecting
to signal ground and the bottom
switch going to pin 7 of IC1b (not
the other way around).
Soft Starter for Power Tools, July
2012: the X2 capacitor specified
in the parts list is a tight fit on
the PCB. Element14 part code
1215460 is a better fit, as is the
Altronics R3129.
well be in order. I would be grateful
if you could provide me with your
thoughts and any possible solutions.
(W. G., Dunedin, NZ).
• The inputs to the PIC are only held
high via internal pull-up resistors and
these may be too high for an application within a fluorescent tube lighting
box. The problem should be solved by
adding 10kΩ pull-up resistors between
the +5V supply and the RB6 & RB7
inputs. Adding 100nF ceramic capacitors between these inputs and the pin
5 ground supply should shunt any
interference to prevent false triggering
(see also the errata in March 2012).
If this doesn’t cure the problem,
the timing board should be shielded
from the fluorescent tubes, starters and
ballast with an earthed piece of tinSC
plate.
Keith Rippon............................... 103
Kitstop............................................ 6
Low Energy Developments........ 103
Matrix Multimedia......................... 11
Microchip Technology..................... 3
Mikroelektronika......................... IBC
Ocean Controls.............................. 8
Quest Electronics....................... 103
Radio, TV & Hobbies DVD............ 99
Reality Design................................ 7
Red Button Technologies............. 63
RF Modules................................ 104
Sesame Electronics................... 103
Silicon Chip Binders................... 103
Silicon Chip Bookshop............... 102
Silicon Chip Order Form............... 95
Silicon Chip Partshop................... 94
Silicon Chip Subscriptions......... 101
Siomar Battery Engineering.... 5,103
Splat Controls............................. 103
Tekmark Australia........................... 6
Truscotts Electronic World.......... 103
Wiltronics...................................... 10
Worldwide Elect. Components... 104
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