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Contents
Vol.31, No.4; April 2018
SILICON
CHIP
www.siliconchip.com.au
R&S RTM3004
touchscreen
’scope has
100MHz bandwidth and is
upgradeable
to 1GHz –
Page 36
Features & Reviews
36 Review: Rohde & Schwarz RTM3004
The R&S RTM3004 gives you the best of both worlds in a single ’scope: great
vertical resolution and low noise, along with high speed performance. It’s also
very easy to use thanks to its touchscreen interface – by Nicholas Vinen
70 New “Facett” hearing aids from BlameySaunders
They look quite different from previous models – not just because of their
“facetted” design. These use rechargeable battery modules which snap into
place using tiny, powerful magnets. But are they any good? – by Ross Tester
76 El Cheapo Modules 15: ESP8266-based WiFi module
The very popular ESP-01 WiFi transceiver module, based on the ESP2866 chip,
is designed to allow almost any microcontroller to connect to a WiFi network.
And best of all: as well as being versatile, they’re really cheap – by Jim Rowe
Constructional Projects
14 230VAC Thermopile-based Heater Controller
Here comes winter! But many radiators don’t have any form of heat control –
they’re either flat out or off – not very satisfactory, as you either cook or freeze!
This controller has two versions – dial up the temperature you want or vary the
heat output over a wide range – by John Clarke
New “FACETT” hearing
aids look very different – and also
use rechargeable magnetic battery
modules – Page 70
Low cost ESP8266-based
WiFi module allows
you to interface
almost any micro
to a WiFi network!
– Page 76
26 Low cost, Arduino-based 3-Axis Seismograph
Following on from last month’s Earthquake Warning Alarm, we add some extra
hardware and software . . . and voila: a true Seismograph, capable of detecting
and recording waves in three directions. We even show you how to record and
analyse them – by Tim Blythman and Nicholas Vinen
58 The Clayton’s “GPS” time signal generator
You don’t need a GPS receiver to get accurate time signals – you can get them
with WiFi. So accurate you won’t tell the difference and you can use them as a
true time reference in critical applications – or just have a time signal that’s as
accurate as the “pips” on the radio! – by Tim Blythman
Your Favourite Columns
You can now give your 230VAC
convection or bar electric radiator dial-up temperature control or
vary the heat output – Page 14.
40 Serviceman’s Log
Why won’t they let me program MY alarm? – by Dave Thompson
53 Circuit Notebook
(1) Temperature and humidity display using PIC16F88
(2) Electric guitar/violin preamp runs off USB supply
(3) Recycling old hard disk spindle motors
(4) Simple valve radio battery eliminator
84 Vintage Radio
1962 Astor M2 Cry-baby: radio, intercom and baby monitor in one – by Ian Batty
Everything Else!
2 Editorial Viewpoint
95 Market Centre
4 Mailbag – Your Feedback 96 Advertising Index
89
Ask SILICON CHIP
96 Celebrating
Notes and
siliconchip.com.au
30 Errata
Years
92 SILICON CHIP Online Shop
A true 3-axis
Seismograph that
can detect and record
earthquake waves in all
directions – Page 26
If you can’t get a
reliable GPS signal
(or don’t have a GPS
receiver) this internet
time signal generator
will do the trick!
– Page 58
April 2018 1
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SILICON
SILIC
CHIP
www.siliconchip.com.au
Publisher
Leo Simpson, B.Bus., FAICD
Editor
Nicholas Vinen
Technical Editor
John Clarke, B.E.(Elec.)
Technical Staff
Jim Rowe, B.A., B.Sc
Bao Smith, B.Sc
Tim Blythman, B.E., B.Sc
Technical Contributor
Duraid Madina, B.Sc, M.Sc, PhD
Art Director & Production Manager
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
Dave Thompson
David Maddison B.App.Sc. (Hons 1),
PhD, Grad.Dip.Entr.Innov.
Geoff Graham
Associate Professor Graham Parslow
Ian Batty
Cartoonist
Brendan Akhurst
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
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Subscription rates: $105.00 per year
in Australia. For overseas rates, see
our website or the subscriptions page
in this issue.
Editorial office:
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Printing and Distribution:
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Editorial Viewpoint
New blood at Silicon Chip
This month I am delighted to welcome two new
members to the Silicon Chip editorial team, Tim Blythman and Duraid Madina. Tim has hit the ground running as he is responsible for two projects in this issue.
Duraid is a part-time technical contributor who is
already busy beavering away on a couple of state-ofthe-art projects which should come to fruition later
this year. We are really looking forward to presenting
them for your enjoyment.
Both these new team members should greatly expand our expertise and
“project generating” capacity and we look forward to a whole range of interesting new possibilities.
Just one of these new possibilities involves more projects based on the
ESP8266 (and related) chips. That’s because these offer an ease-of-use that’s
similar to the Arduino Uno but with inbuilt WiFi, a lot more flash memory
and a much faster CPU.
In effect, you get an Arduino-compatible processor with WiFi but in a smaller, more powerful package – all for a similar or, in some cases, lower price.
The fact that the same chip is available in a range of form factors, from the
Uno-compatible D1 R2, to the smaller but equally capable D1 Mini, and even
the tiny ESP-01, means they are especially flexible.
But it’s the inbuilt WiFi, with easy-to-use libraries, that’s really the “killer”
feature. It makes it so easy and cheap to design projects that fetch data from
or upload data to internet servers and that opens up a huge range of possibilities. It can also allow us to control our designs from a smartphone.
The WiFi Water Tank Level Meter presented in the February issue has
turned out to be very popular. The prototype is in use on my rainwater tank at
home. In this current prolonged dry period in Sydney it has been an important
reference for me to determine how much to water the garden. I can easily check
the water level from the office using my phone.
Still on these WiFi modules, one of the great things about using the Arduino
IDE to program many of the ESP8266 boards is that all you need to re-program
it is a PC (Windows, Linux or macOS) and a USB cable.
And given that many of our designs can be expanded for uses other than
those they were intended for, I hope that readers take advantage of this
capability to extend our concepts. After all, we make the source code available
and there’s nothing stopping you from modifying the code to add new features.
If you do manage to enhance or adapt one of our designs to another application, please write in and let us know. It could even be the subject of a new
project article or an item in Silicon Chip. Consider that we do pay for article
contributions.
If you don’t have any programming experience, Arduino is a good place to
start. While it may seem more daunting than learning a language like BASIC,
the C family of languages it is based on are probably the most widely-used
programming language in existence; your time learning it will be well spent.
And there are a huge number of pre-written libraries available for a range of
tasks, so you don’t have to waste your time “re-inventing the wheel”.
Finally, I hope that our Australian and New Zealand readers will enjoy combing
through the latest Jaycar catalog included with this issue. We always enjoy
such catalogs included in the magazine, since even in these days of internet
searching, nothing can match the convenience of a printed catalog that you
can refer to at any time. You never know when you will come across a nifty
little gadget or component which will be of great use.
ISSN 1030-2662
Recommended & maximum price only.
2
Silicon Chip
Nicholas Vinen
Celebrating 30 Years
siliconchip.com.au
siliconchip.com.au
Celebrating 30 Years
April 2018 3
MAILBAG – your feedback
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”, “Circuit Notebook” and “Serviceman”.
More information on brushless
alternators
I believe that your comments on
brushless alternators on page 62 of
the February 2018 issue, in Serviceman’s log, are valid. Many aircraft use
this type to generate 3-phase 400Hz
115VAC power.
However, in the case of the GMC
units, I think you will find that these
use a different technique. They are
called “capacitor-excited brushless
alternators”.
The rotor has one or two windings,
terminated with a diode. There are
two stationary windings in quadrature.
One of these is the output winding, the
other, known as the auxiliary winding,
is terminated with a capacitor.
This capacitor is crucial for the
unit to self-excite. Increasing the capacitance should increase the output
voltage. The self-excitation relies on
residual magnetism and sometimes it
is necessary to “flash” the stationary
fields to restore this.
These generators are sometimes
known as “harmonically excited” and
as such, are sensitive to the shaft RPM.
I have heard stories about over-voltages occurring during startup with a
load connected. The output waveform
is rarely sinusoidal.
How do they work? I’m not sure but
I believe smoke and mirrors must be
involved somewhere! There is information available on the ‘net. Note that
these generators are not what is meant
by an “induction generator”, which is
an induction motor driven above synchronous speed.
US patent 4786853 details a modification of this type of circuit to adjust
the output voltage but also gives some
explanation of how such a generator
works. See https://patents.google.com/
patent/US4786853
On another topic, an article on aircraft power systems may be of interest
to your readers. The standard changed
from 28V DC in the 1930s to 115VAC
400Hz 3-phase in the 1960s.
These systems were mainly “copper and iron”. Nowadays there are
4
Silicon Chip
all sorts of electronic systems. One of
the challenges is that the prime mover
(typically a gas turbine) does not run
at a constant RPM but varies over a
roughly 2:1 range from ground idle to
maximum thrust.
The solutions include variable
speed alternators with AC/DC converters, followed by DC/AC inverters,
sometimes using the HV DC from the
converter directly.
Some loads are able to use the 350
to 800Hz output directly. There’s
some information on aircraft electrical systems here: siliconchip.com.
au/link/aaj9
Thank you for your most informative magazine.
Norm Smith,
Shoalhaven, NSW.
Brushless alternator used in generator
is quite simple
In the February 2018 issue of SiliChip, in the Serviceman’s Log, B.
P., of Dundathu, Qld, describes the
phoenix-like spells that he performed
on two GMC small generators which
he identified as having no brushes. At
the end of his description, the Editor
copied from Wikipedia a description
of a brushless alternator design.
con
Water Level Sensor supply voltage
not critical
I look forward to my copy of SilChip in my letterbox every
month, thank you. The Water Level
Meter in the February 2018 issue is
a great project.
However, I would like to point
out that the LM358 (IC1) is not required. Simply replace the shunt
with a 150W resistor and you will
get the 3V signal required.
Devices which operate using the
4-to-20mA protocol are very robust. They are designed to operate
with long lengths of cable between
the sensor and measuring device.
So they are very tolerant of voltage
variation.
icon
Celebrating 30 Years
But there is more than one type of
brushless design and the GMC generators, which are the subject of the story,
are not according to the Wikipedia
description.
The design described by Wikipedia
has many auxiliary supporting components and in a modern rendition
there are a large number of electronic
components in the associated voltage
regulator (AVR) and that type of brushless alternator, while eliminating the
brushes, is actually quite complicated.
The GMC generators, like most small
portable generators, could not have
fewer electronic components, namely,
just one capacitor and one diode.
To explain how they work, it is
helpful to digress and contemplate a
half-wave rectifier power supply using a single diode and a transformer.
The transformer has to be de-rated because the DC flowing in the secondary
winding magnetises the laminations,
causing them to saturate during part
of the cycle.
In a similar fashion, the rotating part
of the alternator has laminations and a
Therefore, the sensor does not
need to be powered with exactly
24V. Not only will it work fine at
23.8V, it will also work fine at say
16V.
I also note that under Power Supply Circuitry section, MOD5 is identified as MOD4.
Steve Dyer,
Carrara, Qld.
Comment: thanks for pointing this
out. The specifications supplied with
the Water Level Sensor simply gave a
nominal supply voltage of 24V with
no range, so we were not comfortable
allowing it to vary so much. We have
since seen websites claiming it will
work over a range of 12-36V which
supports your statement.
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Celebrating 30 Years
April 2018 5
single winding with a diode connected
directly across the two ends of the
winding. As the rotor rotates and the
magnetic flux in the rotor alternates,
this causes current to pass in one direction through the rotor coil which
in turn causes the laminations in the
rotor to become magnetised.
In many ways, the rotor now behaves like a permanent magnet rotor.
But when the generator first starts,
there is no current flowing in the stator
windings and so to get the ball rolling,
a winding in the stator has a capacitor permanently across it. So with the
small residual magnetism in the rotor,
current builds up in both that stator
winding and in the rotor until the rotor saturates.
Because the current flowing in the
rotor through the capacitor is out of
phase with the voltage in the capacitor, no power is wasted in that part of
the circuit. A resistive load would also
have worked but that would have been
wasteful. That was the capacitor that
the author had to replace.
Now, with a strong magnetic field
rotating with the rotor, another winding in the stator will also have voltage
induced and it is that other winding
that is connected to the generator’s
output terminals.
By cunning design, which involves
the capacitor winding in the stator being out of phase with the output winding and by tweaking other design features, better voltage regulation can be
achieved than with a simple permanent magnetic rotor.
However, the output waveform is always horrible and the distorted waveshape is load dependent. But for many
purposes this does not matter and as
the design is cheap to manufacture it
is also a popular design. In my experience, the design is associated with
small portable generators.
Dr Kenneth E. Moxham,
Urrbrae, SA.
Some servomotors require
significant bypassing
Thank you for another interesting
edition of Silicon Chip. I only have
one comment about the February 2018
edition and that concerns the use of
the Woodlawn open-cut mine as a tip.
What a waste!
There is an excellent site for a
pumped storage system for the electricity grid and instead, it is being used
as a depository for rubbish.
6
Silicon Chip
Anyway, I have just been through
a fault-finding exercise and it may be
of interest to some readers. I decided
to make another little tricycle-type
robot after reading about the Squee
robot on David Buckley’s website at:
siliconchip.com.au/link/aaja
Edmund Berkeley demonstrated
that complex behaviour could be produced using only some simple boolean
logic and I thought that it might be interesting to replicate it.
However, instead of making an exact
replica, I would implement the logic
using a microcontroller and change
the steering drive to a radio-control
type servomotor.
I purchased a standard servo from
one of the retailers and tested it. But
instead of a smooth precise action
like my other servos, it behaved very
erratically.
I checked the web to see if there were
problems with these servos and there
appeared to be none. I then wondered
what I had done wrong. So, I decided
to buy a second one which behaved in
exactly the same way.
I dismantled one of them and saw
that there was a microcontroller and
a simple Mosfet H-bridge to drive the
motor. The supply was only bypassed
with a 22µF tantalum capacitor. That
did not impress me and I suspected that
the problem may be caused by the high
current when the motor switches on.
To test the idea, I placed a 100µF
low-ESR electrolytic capacitor across
the supply and turned the servo on.
There was a substantial improvement.
I then tried a 470µF low-ESR electrolytic and the servo responded with
considerably less jitter but still some
erratic behaviour. I then looked at limiting the motor turn-on current.
Normally, I limit motor turn-on current with a constant-current circuit.
But that was impossible in this case.
Instead, I decided to insert a small resistor in series with the motor.
The reasoning is that, at turn-on, the
resistor would reduce the surge current substantially. Whereas, when the
motor was running, the resistor would
only cause a small voltage drop.
I inserted a 3.3W resistor and retested the servo. What a difference!
The servo responded smoothly and
precisely, just like my Futaba and
Hitec servos.
Later, I thought about the fact that
there were no complaints on the web.
It occurred to me that normally the
Celebrating 30 Years
servos would be powered by a battery
which could supply large currents.
Consequently, there is little drop in
the supply voltage and the microcontroller is not affected by the motor
turn-on current surge.
In my case, the power had been
supplied from a 7805 regulator with
limited current capability which was
unable to provide the surge current.
It would have been so easy to believe
that the servo was at fault, particularly
when the Futaba and Hitec servos
worked correctly in the same situation.
Anyone controlling a servo from
a Micromite, Arduino, Raspberry Pi,
PICAXE etc should be aware of the
surge demand and take appropriate
steps to address it.
George Ramsay,
Holland Park, Qld.
Comment: this probably could have
been avoided if the designers had included an RC filter and/or regulator
in the microcontroller power supply.
You will notice that some of our designs include such features.
Using an Induction Motor at low speed
with decent torque
The Lath-E-Boy project in the January 2018 issue was quite interesting
and I’d like to offer some ideas for potential improvement.
Mention was made in the article of
operating down to about 5Hz but at
that frequency, I have found the torque
capacity of any induction motor to be
very low.
This is quite the opposite of what
we require for machining, as for
the same surface speed on a larger
diameter cut, when the RPM needs to
be reduced, the torque requirements
are increased. Belt reduction (or any
gearing method, really) provides this
extra torque at low speeds.
Using the IMSC at low speeds, the
spindle speed will, therefore, be unstable with cutting loads and there is
a risk of the motor stalling.
Only “Flux-Vector” or “Field-Oriented” drives are able to produce
150% of rated torque at zero speed on
3-phase motors.
So, I decided to do some bench tests
using the one horsepower, 4-pole permanent split capacitor (PSC) motor
on my pedestal drill. Admittedly, the
characteristics of a PSC motor will
differ from those of a capacitor start
unit but I still think some lessons can
be learned.
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I separated the start winding from its
run capacitor and arranged things so
I could run the motor from my IMSC
with either a) the start winding disconnected, b) connected via the capacitor
(normal), or c) connected to the IMSC’s
extra phase (as per the article). I monitored the power use from the mains
and found the following:
• Switching on at a low speed setting (maybe 10%), with the run capacitor in-circuit, the motor moved but was
unable to start (with belt friction only).
• At the same speed but using the
extra phase drive, the motor would
start but only just keep going once the
phase was disconnected.
• With the capacitor in place, once
running, the drive ran a little better
but it was still fairly easy to stall by
hand. The separate phase drive provided noticeably better torque but still
not that much.
• At an intermediate speed, the
power consumption barely changed
with the “start” winding disconnected
or connected via the capacitor. It drew
the most power at low and high speeds
– the capacitor seemed to “fill out” the
torque curve a little.
• It was still possible to stall the
motor by hand when using the capacitor, but not with the phase connected.
• At full speed the start winding current (measured using a clamp
meter) was much the same with the
extra winding driven via the capacitor or directly from the extra phase. A
surprising result.
• However, the motor power consumption increased by about 50%
with the separate phase drive, so the
motor would be dissipating more heat.
• At an intermediate speed, the start
winding could be left connected without high dissipation (but, I only had
the belt load).
As a result, I feel the following
should provide a useful increase in
lathe torque:
• Leave the start winding connected
to the extra phase for low-speed operation – when the drive voltages are reduced anyway. Use feedback to maintain speed.
• At low-to-intermediate speed,
use relay contacts to change over the
start winding from the extra phase to
a normal run capacitor – a lower-value
unit than the start capacitor may prove
optimal.
• At intermediate-to-high speeds,
fully disconnect the start winding.
8
Silicon Chip
Celebrating 30 Years
Obviously, a larger motor will also
provide a torque improvement.
I had hoped (for the PSC motor) that
I could leave the capacitor in circuit
and only temporarily connect the extra
phase to the start-winding/capacitor
junction but this proved not possible.
The IMSC kept tripping out and indicating a fault.
PSC motors do not have a high
starting torque, so are best only used
for fan and centrifugal pump loads
(ie, low torque requirements at low
speed). It works OK on the drill press
but does tend to “bog down” with bigger drill bits.
I also have a question regarding the
purpose of the “Output Frequency
Sense” circuitry in the Lath-E-Boy.
Given that the IMSC has a 1:1 relationship between Vin and the drive
frequency, is any of this needed? Is
it there to correct for non-linearities
in the PWM outputs of OPTO2 or the
IMSC input?
Either way, this only controls the
output frequency, not the spindle
speed; increased slip in the induction motor slip will result in a lower
spindle speed and this depends on the
motor loading.
A more accurate method to “close
the loop” would be to measure the
actual spindle speed, using say, a
magnetic pickup and feed this back
through the “READ RPM” circuit.
Ian Thompson,
Duncraig, WA.
Comment: thanks for this information. As you suggested, we expect the
feedback as presented in the project
article would primarily act to cancel
out non-linearities in the optocoupler.
Valves with similar functions
can have different pinouts
The Vintage Radio article on the
Philips 148C in the March 2018
issue was, as usual, a great read.
When I came to the description of the
apparently miswired 3V4 output valve
socket on page 95. I remembered from
my early days in the 60s, messing
around with battery valve sets and
construction projects, that there were
two “3”-series battery pentode output
valves, the 3V4 being one of them.
But it was so long ago that I had to
consult my trusty Miniwatt valve data
manual to find the other.
It was the 3S4 and from what I can
determine from the description in
the Vintage Radio article, the wiring
siliconchip.com.au
would appear to suit the 3S4 and not
the 3V4. They are similar valves but
with different internal connections.
The pinouts are as follows:
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Pin
3V4
3S4
1
F-
F-
2
A
A
3
G2
G1
4
NC
G2
5
FT-G3
FT-G3
6
G1
A
7
F+
F+
Ian Sorensen,
Toodyay, WA.
Criticism of Lathe controller design
Ethernet Digital IO
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10
Silicon Chip
I am disappointed in the “Lathe-EBoy” machine tool motor speed controller. I think your designer has not
fully grasped all the essential requirements of a machine tool VSD (variable
speed drive) that a machinist desires
in order to exploit the full utility of
their machine. There are two glaring
omissions in the design.
Firstly, the controller needs to automatically ramp the spindle speed up
and down when doing long facing
cuts; typical of faceplate turning work.
This is to maintain the optimal
surface speed when the cross-slide
is auto-traversed toward the centre.
The spindle-speed must increase
geometrically in concordance with
the reduction in diameter and vice
versa.
This is achieved by the installation
of slide-scales in typical DRO (digital
read-out) installations. These retrofits
are now de rigueur and are cheap and
readily available (mostly from Asia, eg,
via eBay or Alibaba).
Just about every other article in
the engineering hobby magazines describes an amateur machinist retro-fit
to their lathe or mill.
Once installed, it would be a simple
matter to implement this feature via a
circuit/software interface.
Secondly, electric braking is required. I think your designer has not
grasped the importance of this feature.
It's not just for safety reasons (although
that is most important) but rather, it
has general utility as an aid to certain
machining operations. For example,
machining up to a shoulder, such as
when threading into a corner.
This is normally implemented by
Celebrating 30 Years
means of an adjustable stop-rod closing a microswitch connected to the
controller. With this method, optimal
spindle-speeds can be safely used
without fear of mis-timing the stoppoint (ouch!).
It’s probably also worth mentioning
that it is a great pity that the Induction
Motor Speed Controller could not be
up-rated to handle three horsepower
(2.2kW) motors.
These generally represent the typical upper-limit of what would be
found in a great many amateur workshops. Look at the used and new machine-tool listings and you’ll see what I
mean. For example, the Harrison M300
lathe commonly uses a 3hp motor.
Andre Rousseau,
Auckland South, NZ.
Peter Bennett, the designer, replies:
the design intent was to minimise belt
changes on a very simple lathe that
hobbyists may have in their workshop,
not try to convert the lathe into a more
modern design or one suited to commercial production work.
With enough time, effort and expense, we could turn it into a full CNC
machine, but that is beyond the original scope of the project.
Regarding the power rating of the
Speed Controller, we arrived at a
1.5kW rating as this is about as high
as you can easily go with the power
source being a 10A GPO.
While 10A mains can nominally
provide up to 2300W, the fact that the
mains is rectified to provide pulsating
DC which is then switched to the motor drive causes the input current to
be higher than you might expect for a
given output power.
A hare-brained scheme
I saw your November issue featuring the Dipole Loudspeaker System
(siliconchip.com.au/Article/10865)
and this sparked some interest from
me. My friend and I have been working on a project centred around exciter
speakers but which has nothing to do
with audio sound reproduction.
While working with exciters, as a
matter of curiosity I mounted various
types of exciters under my dining room
table, side boards, work benches coffee table etc and have played many a
song through this system.
My friend even mounted two on
the bottom of a acoustic guitar and he
clowns around playing guitar songs
and hamming it up as if he is the
siliconchip.com.au
actual guitar player. The strings even move in tune with
the sound.
To me (through my half deaf ears) the sound reproduction is surprisingly good. So the favour I am asking of you
is to write an investigative article exploring just how good
the sound really is with this arrangement. I think it would
make an interesting article and perhaps answer my question on just how good that sound really is.
My favourite exciter is the Dayton HDN-8 40W 8W unit.
Bob Young,
Mt Waverly, Vic.
Leo Simpson responds: Surely, you are joking Bob.
As useful as these devices are, there is no way that an
exciter bolted to a wall, ceiling or any other panel can
give full-range sound.
While the device has a stated frequency range of 40Hz
to 15kHz, no timber, gyprock or any other panel material is likely to produce frequencies above 3 or 4kHz, at
best. Another hurdle is that the device has a resonant
frequency of 695Hz. How would you get a flat response
below that point?
I cannot see much point in doing exhaustive tests when
it would be quite simple to do a straightforward comparison test of a full range hifi loudspeaker system with an
exciter bolted to a panel; any panel, box, wardrobe, coffee
table or coffin.
Coax quality matters when installing a TV antenna
First of all, congratulations on your 30-year milestone.
I have every issue going back almost that far and can see
how the quality of the magazine has improved by leaps
and bounds. I am always impressed and learn many things
each month from the magazine.
I just wanted to add a few comments regarding the VHF
antenna project in the February 2018 issue. I realise we
are only talking VHF here but for best noise immunity, I
would use nothing less than RG6 (quad shield) coax. The
best fittings to use for terminating the coax are the F-type
rather than the saddle type.
It is also worth adding a masthead amplifier to improve
the signal-to-noise ratio at the start of the run, if long runs
are likely or if the signal is to be split for extra outlets. The
crimping tool, F connectors and RG6 coax are all available
at Bunnings now, as well as Jaycar, Altronics etc.
Geoff Coppa,
Alstonville, NSW.
Differences between Australian and Chinese mains plugs
Thanks for printing my switchmode power supply
repair story, in the Serviceman’s Log section of the February issue. I think it was a pity you didn’t print the circuit
diagram I supplied, which showed how the rectifier bridge
could be configured as a voltage doubler for 110VAC mains
and full-wave rectifier for 230VAC mains. I thought that
was a smart way to use a link to achieve this.
Having said that, nowadays, most switchmode power
supplies will work over a range of something like 100250VAC at 50Hz or 60Hz, so you can just plug them in,
anywhere in the world and they will work without any
changes.
That means you can often import mains-powered equipment from overseas and it will work in Australia.
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Celebrating 30 Years
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But one thing that’s often missing from such imported
equipment, but is present on all modern Australian gear,
is the insulation at the base of the Active and Neutral pins.
It seems that in some places in China, they use a plug like
ours but they don’t have the pin insulation.
Roderick Wall,
Mount Eliza, Vic.
Comment: the standard Chinese 3-pin mains plug is
indeed very similar to ours but there are some key differences, besides the lack of insulation at the base of the
pins that you mentioned.
These are that the pins are not quite as thick as an
Australian plug and the plastic insulation is usually a lot
thinner (making for a more compact plug).
Note that in China, a different plug and socket is used
for two-pin appliances and it appears very similar to that
used in the USA (ie, two parallel rectangular pins).
The pin thickness can be an issue because it means that
the plug may not be very secure in an Australian socket.
And while you can plug Australian gear into a Chinese
GPO, it’s usually a very tight fit!
The smaller plastic housing is arguably less safe as it’s
easier to break, so it’s best to chop them off and wire in
a proper Australian plug. You should also be aware that
such equipment may not be built to the same safety standards as gear sold in Australia.
Portable battery mains power supply wanted
The other day I was outside using an electrical appliance connected by an extension cord. These days the trend
has been to battery-powered appliances with convenience
and portability being the main drivers.
The thought came to me: for those with mains-powered
appliances, why doesn’t someone design a portable inverter that fits into the likes of a small backpack or “bum
bag” which the 230VAC appliance can be plugged into? I
was thinking that lithium-ion battery packs that are used
to power battery tools could be the source of power, either
stripped down for the batteries or connected with suitable
adaptors.
I am not sure on the legalities/safety issues, although
we can dangle 230VAC extension cords around the garden with “no worries”. I assume they could be designed
with appropriate safety measures in mind.
I would be interested in your thoughts.
Peter Ward,
via email.
Response: while theoretically possible, we don’t think this
would be terribly practical. Safety issues aside (I certainly
don’t like the idea of having a mains inverter strapped
to my body!) even a large battery pack would struggle to
provide more than a few minutes of runtime for an appliance which may draw well over 1000W when operating.
It would also be quite cumbersome and heavy.
Theremin featured in Australian movie
The playing of the Theremin is a major part of last year’s
movie, “3 Summers”. It will be available for home viewing in March this year. To see a preview, which includes
a Theremin being played, see www.transmissionfilms.
com.au/films/three-summers
A. Hughes,
Hamersley, WA.
SC
siliconchip.com.au
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Celebrating 30 Years
April 2018 13
Just in time for winter . . .
Infrared Sensing
Heater Controller
With summer rapidly becoming a distant memory, you will no doubt be
dragging out the heaters to stay warm. Our new Heater Controller allows
you to select exactly how much warmth you want from the heater and it
can even be fitted with a thermopile sensor for precise temperature control.
M
ost electric radiators are
pretty crude devices: you
switch ’em on and they get
hot.
But in small rooms, they will quickly get too hot and then you will want
to switch them off or possibly down a
level or two, if they have such a switch.
Most heaters pump out too much
heat for a small room, even when they
are on the lowest setting. You really
need a heat controller. Our new Heater
Controller is exactly what you want.
Think of it as a “dimmer for radiators”.
But it is a lot more than that.
We should note that some heaters,
typically oil-filled units, do have a
thermostat where the heater switches
off when the air temperature reaches a
set value and then it switches back on
when the heater cools down.
The thermostat is usually mechani14
Silicon Chip
cal and often makes a clicking noise
whenever the switching occurs and it
may also cause a neon or LED to flash
on and off at the same time.
That intermittent noise and light
may be be disturbing if the heater is
used in a bedroom while you are trying to get to sleep.
It can also result in a noticeable
heating/cooling cycle if you are close
to the radiator.
Our new Heater Controller has no
mechanical switching to cause noises
and it incorporates a thermopile infrared sensor so it can maintain a set
temperature in a room.
Alternatively, it can be built without the optional infrared sensor so you
can use it to simply select the amount
of heating that you desire.
by John Clarke
Celebrating 30 Years
We should point out that the Heater
Controller is not suitable for fan heaters. At the lower settings the fan will
not run and that could cause the unit
to over-heat and fail.
How it works
Our Heater Controller works by applying an integral (ie, whole) number of full mains voltage cycles to the
heater.
At lower power settings, fewer cycles are applied and for higher power,
a greater number are applied. We have
included a number of scope grabs to
illustrate this switching operation.
For example, at low power, it may
only apply one cycle of 50Hz 230VAC
out of every 15. At full power, the
mains voltage is on constantly (as if
the controller was not present).
It uses a 15-cycle control period,
siliconchip.com.au
The Heater Controller can be
built in two versions:
with a thermopile
sensor for accurate
temperature control;
or without, which
allows you to vary
the power over 15
different levels. The
model shown here
has the thermopile
sensor so you can
“dial up” the
temperature
you want.
which corresponds to 300ms for 50Hz
mains (like in Australia, New Zealand
and the UK) or 250ms for 60Hz.
At half power, there are seven or
eight cycles of mains voltage applied
to the heater out of 15 incoming cycles.
The switching action will not be noticeable with heaters with wound resistance elements but it will be visible
with radiator elements in silica glass
tubes and very noticeable in those with
halogen lamps.
In fact, the flashing of halogen lamps
in those heaters will drive you bonkers! Don’t do it.
The mains voltage is only switched
as it passes through zero volts (ie, “zero-voltage switching”).
This minimises any generation of
electromagnetic interference by the
controller.
Two versions
As noted, this project can be built in
one of two versions,
with or without a
thermopile sensor
for temperature control. If you build it
without the optional
thermopile sensor,
the knob on the front
panel will allow you
to vary the power
siliconchip.com.au
over 15 different power levels.
The second version, with the thermopile sensor, provides a non-contact
temperature measurement method by
detecting the infrared radiation emitted by objects outside the box.
This form of room temperature sensing is ideal since the Heater Controller’s circuitry runs at 230VAC mains
potential and contact with an uninsulated external sensor would be dangerous.
By having the thermopile located
safely inside the unit, with a transparent window for insulation, it is
rendered safe and its operation is not
affected by self-heating due to internal dissipation, as would be the case
with an internal sensor.
The Heater Controller can be used
with a 220-250VAC mains supply at
50Hz or 60Hz. It is not suitable for
use with 110VAC supplies without
some changes being made to the power supply and mains voltage detection
circuitry.
As you can see from the photos, the
Heater Controller is mounted in a lowprofile diecast aluminium case with
mains plug and socket leads at one
end, along with a fuse holder. The adjustment potentiometer is on the lid.
Circuit description
The complete circuit for the Heater
Controller is shown in Fig.1. We’ll start
by describing the complete version
which provides temperature control.
The circuit is based around microcontroller IC1, Triac Q2 and thermopile sensor TS1.
IC1 provides overFeatures & specifications
all control, driving
3 Controls 230VAC heaters up to 10A/2300W.
the sensor and the
3 Suitable for use with bar heaters, ceramic heaters or oilTriac which confilled convection heaters. Not suitable for halogen or fan heaters.
nects mains power
3 220-250VAC mains operation, 50Hz or 60Hz.
to the heater.
TS1 has four pins
3 Heating power or Temperature control
and it actually com3 Power control: 15 steps from low to full heating power.
prises two separate
300ms (50Hz) or 250ms (60Hz) cycle.
devices in the one
3 Temperature control: 15-31°C in 1°C steps.
package. The thermopile IR sensor is
3 Zero voltage switching for low interference.
3 Triac gate drive: 68mA pulse for 300µs after each zero voltage crossing. connected between
pins 2 and 3 while an
q
q
q
q
q
q
q
q
Celebrating 30 Years
April 2018 15
WARNING!
The Heater Controller operates directly
from the 230VAC mains supply and contact
with live components is potentially lethal.
Fig.1: circuit diagram of the Heater Controller. IC1 monitors the mains zero crossing at pin 5, potentiometer setting at pin
6, the internal temperature at pin 3 and external temperature difference at pin 7. It uses this information to decide when
to deliver a gate pulse from pin 2, to switch on Triac Q2 which applies one cycle of mains power to the heater at a time.
NTC thermistor is connected between
pins 1 and 4.
This is important since the thermopile senses the difference in temperature between the room and the sensor itself.
The thermistor allows us to determine the sensor temperature. By adding the two temperatures, we can determine the absolute temperature of
the room.
The microcontroller monitors several signals or voltages, which are internally converted to numbers using
its inbuilt 10-bit analog-to-digital converter (ADC).
The voltage across the NTC thermistor in TS1 is monitored by input
AN3 (pin 3), while the voltage at the
output from instrumentation amplifier
IC2 is monitored at input AN0 (pin 7).
The setting of the control potentiometer, VR1, is monitored at input
AN1 (pin 6) while the mains voltage
is monitored at digital input GP2 (pin
5), via a 330kΩ 1W resistor.
IC1’s GP5 output (pin 2) drives the
base of NPN transistor Q1. Q1, in turn,
sinks current from the gate of Triac Q2,
switching it on.
Its gate current flows via the 47Ω resistor connected between the 5.1V supply and the A1 terminal, through the
gate and then to circuit ground via Q1.
This is a slightly unusual configuration. The gate resistor (in our case,
47Ω) is normally placed between the
Triac gate and transistor collector, with
the A1 terminal connected directly to
the supply (in our case 5.1V).
However, with that arrangement,
noise on the mains Active conductor
could be injected into the microcontroller supply and cause it to latch up.
In our circuit, the 47Ω resistor between the mains Active and 5.1V sup-
ply provides isolation to avoid this
problem while still limiting the gate
current in exactly the same manner.
Q2’s A1 terminal connects to the incoming mains Active supply via a 10A
fuse. Q2 is used as a switch for making power connection from mains Active to the heater, via the A2 terminal.
The DC supply for the microcontroller is derived directly from the
230VAC mains supply via a 470nF
275VAC X2 rated capacitor in series
with a 1kΩ 1W resistor.
The capacitor’s impedance limits
the average current drawn from the
mains while the 1kΩ resistor limits
the surge current when power is first
applied.
It works in the following way. When
the Neutral line is positive with respect to the Active line, current flows
via the 470nF capacitor and diode D1
to the 470µF capacitor to charge it
The first in this
series of scope grabs
shows the zerovoltage switching
action of the Triac.
The remainder show
how the number of
cycles is increased to
increase the power.
16
Silicon Chip
Celebrating 30 Years
siliconchip.com.au
What is a Thermopile?
up. On negative half-cycles, the current through the 470nF capacitor is
reversed via diode D2.
Zener diode ZD1 limits the voltage across the 470µF capacitor to 12V
and that supply then feeds a second
470µF capacitor via a 47Ω resistor and
its voltage is limited to 5.1V by zener
diode ZD2.
This is the supply for the microcontroller, IC1 and it is decoupled with
a 100nF capacitor close to the micro.
IC1 monitors the GP3 digital input at
pin 4 and this can be tied to the 5.1V
supply or to 0V using a jumper shunt
at JP1. When this pin is pulled high,
the reading from VR1 is used to control the percentage of full power delivered to the heater.
When this pin is pulled low, the heater is temperature controlled instead, using TS1 for feedback.
VR1 is connected across the 5.1V
siliconchip.com.au
A thermopile is a “pile” of
thermocouples that are exposed to the outside via an infrared window. A thermo-couple is a junction between two
dissimilar conductors, bonded
together as shown.
One set of junctions is exposed to infrared energy while
the other set is shielded from
the infrared and thermally connected to a reference thermal
mass. This is indicated as a heatsink in the diagram.
The thermopile we are using has 60 thermocouples connected in series, so their voltages are added together.
The output voltage from the thermopile varies with the difference between the temperature of the infrared-exposed junctions and the heatsink-connected junctions. If the infrared radiation heats the first set of junctions up to the same temperature as the heatsink,
then their output will be at 0V.
The output voltage can be positive or negative, depending on whether the heatsink connected junctions are colder (positive) or hotter (negative) than the infrared exposed junctions.
The fact that the temperature measurement is based on received infrared energy means
that this is a non-contact method of temperature measurement. All objects which are above
absolute zero give off some infrared energy and the hotter they are, the more they emit,
hence we can use this energy as a way to remotely sense temperature.
The sensor we are using also includes an NTC thermistor which is joined to the heatsink.
This allows the heatsink temperature to be measured. The temperature of the monitored
object (ie, the source of infrared energy) is the heatsink temperature plus the temperature
measured by the thermopile.
So if the thermopile package temperature is 25°C, as measured by the thermistor, and
the thermopile infrared temperature measurement is registering 4°C then the actual temperature measurement is 29°C (25°C + 4°C). If the thermopile registers -3°C then the result is 22°C (25°C - 3°C).
The thermopile includes an infrared-transparent window that allows the infrared energy
into the thermopile. We are also using an external lens, to protect against accidental contact with the circuitry on the inside of the box.
One more thing to note about thermopiles: while we said above that the infrared emissions from an object depend on its temperature and that is true, they also depend on the
colour of the object’s surface.
A “black body” is an ideal emitter with an emissivity of 1.0 and the thermopile is calibrated to accurately measure the temperature of such objects. All other objects have an
emissivity between zero and one and as a result, the thermopile will pick up less infrared
energy at any given temperature and so will measure less than their actual temperature.
Examples of objects with low emissivity includes most shiny objects, for example, with
polished metal surfaces. To accurately measure the temperature of an object based on infrared energy, you need to know the emissivity and divide the measurement by this value.
In the case of our Heater Controller, the emissivity of a typical room should be high
enough, and the difference between internal and external temperature low enough, that
such compensation should not be necessary.
We do, however, suggest that you avoid pointing the IR window at very shiny objects.
Celebrating 30 Years
April 2018 17
Fig.2: follow this overlay and
wiring diagram to build the full
version of the Heater Controller,
which is capable of operating in
power control or temperature
control modes, as determined by
the position of jumper JP1.
supply with the wiper connected to
the AN1 input, as described earlier.
The 100kΩ resistor from the wiper to
ground holds the AN1 input at 0V, setting the control to minimum, should
VR1’s wiper go open circuit.
Temperature measurement
The resistance of the thermistor in
TS1 decreases with increasing temperature and therefore it has a negative temperature coefficient (NTC).
Its value at 25°C is close to 100kΩ and
will be reduced at higher temperatures.
Its resistance is monitored indirectly
at the AN3 input of IC1, by connecting
the thermistor as part of a voltage divider, ie, with a 100kΩ resistor to the
5.1V supply.
The resulting voltage is converted to
a digital value in IC1 and that value is
used to compute the sensor temperature
in °C using a table that lists the expected
voltage against temperature.
With the thermistor at 25°C, given
that its resistance of 100kΩ matches
that of the fixed resistor, the voltage between NTC- and NTC+ should be half
of the 5.1V supply (ie, around 2.55V).
The thermistor resistance changes in
a non-linear manner with respect to
temperature.
This online calculator can be used
to determine how the thermistor resistance varies with temperature, by plugging in a Beta value of 3960 and a resistance at 25°C of 100kΩ: siliconchip.
com.au/link/aaj1
For example, we can determine that
if the sensor is at 15°C, the thermistor
resistance will be around 158556Ω, giv18
Silicon Chip
ing a voltage of 3.13V (5.1V x 158556Ω
÷ [158556Ω + 100kΩ]) across the thermistor (ie, at Vout1), assuming the supply voltage is exactly 5.1V.
So that determines the temperature
of the sensor itself. The thermopile output voltage allows us to determine the
difference between the sensor temperature and the room temperature, but it is
Celebrating 30 Years
a very small voltage and needs amplification before it can be measured by IC1.
To achieve this, we use an instrumentation amplifier (IC2). The amplifier
gain is set at about 211 by the value of
resistor Rg, 470Ω. This amount of gain
gives IC2’s output a slope of 10mV/°C.
The gain takes into account the losses
in infrared heat through the lens used
siliconchip.com.au
Fig.3: this diagram shows which components can be omitted, to build the unit
only for heater power control only. JP1 is replaced with a wire link and two
additional wire links are fitted where shown. The photo below is of the full
version and shows all wiring completed and secured, as in the diagram opposite.
to cover the sensor.
The output voltage of IC2 is referenced against a non-zero voltage so that
we can measure the room temperature
even if it is colder than sensor TS1.
So if the output from IC2 is at this
reference voltage, the thermopile measurement is zero degrees (ie, ambient
equals sensor temperature). The refersiliconchip.com.au
ence voltage is set by trimpot VR2 to
half-supply, ie, 2.55V.
If the output of IC2 is 20mV above the
reference voltage then the temperature
difference is +2°C.
The micro adds this differential temperature to the sensor temperature,
computed as explained above, to gauge
the room temperature.
Celebrating 30 Years
The negative end of the thermopile
(pin 3 of TS1), which connects to the
inverting of IC2 (pin 2) is connected
to ground.
Thus, the positive output of the thermopile, at pin 2 of TS1, can vary above
or below ground, depending on whether
the outside temperature is above or below the sensor temperature.
The thermopile is a voltage source
and it can generate a negative voltage,
despite the circuit not having a negative supply.
However, instrumentation amplifier
IC2 is capable of handling input voltages down to 150mV below its negative supply.
The thermopile output voltage is
typically within ±1mV so this is not
a problem.
The 100nF capacitors at the AN0,
AN1 and AN3 inputs of IC1 provide a
low impedance source for the analogto-digital converter’s sample-and-hold
circuitry.
Zero voltage crossing detection
Pin 5 of IC1 (GP2) is a Schmitt trigger
digital input. This monitors the mains
Neutral via a 330kΩ resistor and is filtered with a 4.7nF capacitor. An interrupt in IC1 occurs whenever the voltage changes from a high (around 4V) to
a low level (around 1V) and also from
a low to a high.
That interrupt occurs when the mains
voltage swings through zero volts in either direction. The interrupt tells IC1
that the voltage of the mains has just
passed through 0V.
This allows IC1 to synchronise gate
triggering with the mains waveform.
Note that the 4.7nF capacitor at pin 2 introduces a phase lag (delay), but this is
compensated for within IC1’s software.
The voltage at pin 5 is clamped by
IC1’s internal protection diodes. They
clamp at +5.4V and -0.3V. Since the
5.1V supply for IC1 is essentially connected to the mains Active via the 47Ω
resistor, the sensed Neutral voltage is
relative to the 5.1V supply.
Controlling power level only
If you only want to be able to control the heater power and don’t need
temperature regulation, jumper JP1 is
set to pull pin 4 of IC1 high. In this
case, there is no need to install TS1
or IC2, trimpot VR2 nor any of the associated resistors and capacitors (see
Fig.3). This would reduce the cost of
building the unit.
April 2018 19
Parts list – Heater Controller
1 double-sided PCB coded 10104181, 103 x 81mm
1 diecast aluminium box 119 x 94 x 34mm [Jaycar HB-5067]
1 Fresnel lens for IR sensor (Murata IML0688) [RS components Cat 124-5980] †
1 M205 10A safety panel mount fuse holder with 10A M205 fuse (F1) [Altronics S5992]
1 4-way PC mount terminal barrier (CON1) [Jaycar HM-3162]
1 3-way PC mount terminal block with 5.08mm pin spacings (CON2)
2 cable glands for 5-10mm cable
1 DIL-8 IC socket
1 3-pin header with 2.54mm spacing and shorting block †
1 2m long 10A mains extension lead
1 knob to suit VR1
4 4mm eyelet connectors
4 8mm long M3 tapped Nylon spacers
3 M4 x 10mm screws
2 4mm ID star washers
3 M4 hex nuts
8 M3 x 5mm machine screws
4 stick-on rubber feet
10 PC stakes †
1 100mm length of 3mm diameter heatshrink tubing
1 25mm length of 6mm diameter green heatshrink tubing, if required for eyelet lugs
3 100mm lengths of 250VAC 7.5A mains wire (for VR1)
4 100mm long cable ties
Semiconductors
1 PIC12F675-I/P microcontroller programmed with 1010418A.hex (IC1)
1 AD623AN instrumentation amplifier (IC2) †
1 ZTP135SR thermopile sensor (TS1)‡ [element14 Cat 2506255]
1 BTA41-600BRG insulated tab 40A 600V Triac (Q2)
[element14 Cat 1057288, RS Components Cat 687-1007]
1 BC337 NPN transistor (Q1)
1 12V 1W (1N4742) zener diode (ZD1)
1 5.1V 1W (1N4733) zener diode (ZD2)
2 1N4004 1A diodes (D1,D2)
Super glue, heatsink compound, solder
Capacitors
2 470µF 16V PC electrolytic
1 10µF 16V PC electrolytic †
1 470nF 275VAC X2 class
7 100nF 63V or 100V MKT polyester ‡
1 4.7nF 63V or 100V MKT polyester
Resistors (0.25W, 1%)
1 330kΩ 1W
2 100kΩ §
1 1kΩ †
1 1kΩ 1W
2 470Ω §
1 20kΩ multi-turn top adjust trimpot (code 203, 3296W style) (VR2)†
1 10kΩ linear 24mm potentiometer (VR1)
2 47Ω
(† not required for power control only version)
(§ 1 required for power control only version)
(‡ 2 required for power control only version)
* depends on version
o
o
o
o
o
20
Qty.
1
1/2*
1/2*
1/2*
1/2*
Value
330kΩ
100kΩ
1kΩ
470Ω
47Ω
Silicon Chip
Resistor Colour Codes
4-Band Code (1%)
orange orange yellow brown
brown black yellow brown
brown black red brown
yellow violet brown brown
yellow violet black brown
5-Band Code (1%)
orange orange black orange brown
brown black black orange brown
brown black black brown brown
yellow violet black black brown
yellow violet black gold brown
Celebrating 30 Years
Note that it would be possible to
build the unit so that it could be used in
either mode, by fitting a 250VAC-rated
single-pole double-throw toggle switch
to the box and wiring it in place of JP1.
In percentage control mode, the
temperature sensed by TS1 would be
ignored.
Construction
The Heater Controller is built on
a double-sided, plated-through PCB
(printed circuit board) coded 10102181
and measuring 103 x 81mm. This is
mounted inside a diecast box of 119 x
94 x 34mm.
Fig.2 shows where the components
are fitted for the full version, which can
regulate the temperature, while Fig.3
shows just the components fitted which
are required for controlling the heater
power level (percentage).
Follow the overlay diagram appropriate to your version. Start by installing the resistors. Table 1 shows the
resistor colour codes but you should
also check each resistor using a digital multimeter.
Three additional wire links are fitted
for the heater power control only version. These are shown in Fig.3; one to
set the mode, in place of JP1, and two
to hold the AN0 and AN3 inputs of IC1
at 0V. Use resistor lead off-cuts to make
these links now.
Following this, install the diodes
which must be orientated as shown.
Note that there are several different diode types: standard 1N4004 diodes for
D1 and D2, a 12V 1W zener (1N4742)
for ZD1 and a 5.1V 1W zener (1N4733)
for ZD2.
IC1 is mounted on an 8-pin DIL
socket so install its socket now, taking
care to orientate it correctly. Leave IC1
out for the time being, though. IC2 is
installed for the full version, soldered
directly on the PCB. Transistor Q1 can
also be installed now.
Fit the capacitors next. The X2 class
capacitors and the polyester types usually are usually printed with a code to
indicate their value; see the small capacitor codes table.
Small Capacitor Codes
Qty. Value
F
Code
o 1 470nF 0.47F
o 2/7* 100nF 0.1F
o 1 4.7nF .0047F
EIA
Code
IEC
Code
474
104
472
470n
100n
4n7
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Celebrating
30C
Years
April 2018 21
Fig.4: this diagram
and the photos at right
and below show how
the sensor is mounted,
with its lens emerging
through an 11mm hole
drilled through the
side of the case.
The electrolytic types are marked
with their F (microfarad) value and
must be oriented with the polarity shown. The longer lead is positive while the negative end is usually
marked on the can with a stripe.
The screw terminals and trimpot can
be installed now. The 3-way terminal
block for CON2 is fitted with the lead
entry toward the lower edge of the PCB.
VR2 has its adjustment screw near the
top edge of the board, as shown in
Figs.2 & 3. If fitting a pin header for
JP1, solder this in place now.
TS1 is fitted for the full version and
is mounted along the edge of the board.
This arrangement is shown in Fig.4.
The sensor is located centrally within
the cut-out on the side of the board,
with the leads to pins 1 & 2 along the
top of the PCB and the leads to pins 3
& 4 along the underside.
You can either use PC stakes to connect the lead of TS1 to the PCB terminals or bend the sensor leads to fit into
the PCB holes directly. Make sure the
leads for pins 1 and 2 do not short to
the pads on the PCB for pins 3 and 4; a
small piece of electrical tape or heathsrink tubing could be used to insulate
them from the board.
Any pigtails on the underside of the
PCB, including the ends of PC stakes,
must be cut short to prevent contact
with the base of the sensor. Leave Triac
Q2 to be installed later.
Preparing the case
Now you need to drill some holes
in the diecast enclosure. Drilling templates are provided in Fig.5. The lid
requires a 9.5mm diameter hole for
potentiometer VR1 and a 4mm Earth
screw hole so drill them now.
22
Silicon Chip
ORIENTATION
TAG
ZTP135SR
HEATSHRINK
TUBING
If building the full version, follow
the instructions below. Otherwise, go
to the heading titled “PCB location”.
The first hole that needs drilling in
the box base is that for the lens. This
is on the side of the box and is 9mm
in diameter.
Once drilled, fit the lens into the
hole with the two protruding locating
prongs on the rear rim of the lens housing both facing downward. Attach three
of the four 8mm spacers to the PCB with
the screws from the top of the PCB. The
omitted spacer can be the one nearest
VR2 or near fuse F1.
Now place the PCB into the box with
the thermopile sensor entering the lens.
While holding the PCB in place, press
the PCB toward the lens so that it is
held tightly in place.
Align the PCB so it is squarely positioned in the box and mark the mounting hole position for the missing spacer
on the base of the box, then drill this
hole to 3mm and check that the hole
is correctly positioned.
If adjustment is needed, file the hole
with a small needle file so it is correctly
positioned. Once correct, remove the
spacers and lens and place the PCB in
the box. Align it with the hole already
drilled. When the PCB is squarely positioned, mark out and drill the remaining three holes.
PCB location
Note that when the PCB is in the
box, the CON1 screw terminal end of
the PCB sits further away from the end
of the box compared to the other end.
This allows space for the cable gland
nuts. Holes for the fuse, cable glands
and Earth screw can also be drilled
now, making sure these are drilled at
Celebrating 30 Years
the CON1 end of the box.
Re-attach the 8mm long spacers to
the PCB. Then bend the Triac leads up
at 90°, 4mm from the body of the Triac. Insert the leads into the PCB from
the underside.
The PCB can now be secured to the
case with the screws from the underside into the tapped spacers. Mark out
the Triac mounting hole position on
the base of the case. Remove the PCB
again and drill to 4mm. Clean away
any metal swarf and slightly chamfer
the hole edge.
Re-attach the PCB and adjust the
Triac lead height so the metal tab sits
flush onto the flat surface, then secure
the Triac with the M4 screw and nut.
Note that the metal tab is internally
isolated from the leads and so does
not require any further insulation between its tab and case. Solder the Triac
leads at the top of the PCB, then trim
them short.
Now remove the screws to gain access to the underside of the PCB and
solder the Triac leads from the underside. The four rubber feet can be
attached to the base of the case now.
The case lid should be fitted with a
panel label. We have designed three labels. One is for the power-control only
version, one is for a temperature-control only version and the third option
is for when JP1 can be used to select
either control mode. These label files
can be downloaded from our website
(www.siliconchip.com.au).
Once the label has been attached,
cut out the potentiometer hole and
Earth screw hole with a hobby knife.
Wiring
Cut the 10A extension lead in two,
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to provide one lead with a plug on the
end and another with a socket. Where
the lead is cut depends on how long
you prefer each lead.
You may prefer a long plug cord
and short socket lead, so the heater is
located near to the controller. Alternatively, the lead can be cut into two
equal lengths. Before cutting though,
make sure you have sufficient length
to strip back the insulation as detailed
in the next two paragraphs.
Strip back the outer insulation
sheath by about 200mm on the socket
lead so you can get a suitable 100mm
length of Earth wire (green/yellow
stripe) for the connection between the
chassis and lid.
Then cut the blue Neutral wire and
brown Active wires to 50mm. Some of
the spare 150mm brown wire length
can be used later to connect from the
fuse to CON1.
The plug lead outer sheath insulation should be stripped back to expose
100mm of wire. This leaves sufficiently long Earth and Active leads. Cut the
Neutral wire to 50mm. Pass these wires
through the cable glands and connect
as shown in Fig.2, stripping back the
insulation before terminating to the
fuse and CON1.
Make sure the plug lead and socket lead are placed in the correct cable
gland and wired as shown. Note that
when wiring the fuse holder, heatshrink tubing should be placed over
the wire terminals. Heatshrink tubing
3mm in diameter is suitable. Pass the
wires through the tubing before soldering to the terminals.
Cut the shaft of VR1 to 12mm long
and file the edges smooth. Then attach the three 100mm lengths of 7.5A
mains rated wire to its three terminals
and cover with 3mm heatshrink tubing. The other ends connect to CON2.
These wires are held in place using a
cable tie that feeds through holes in
the PCB.
Attach VR1 to the lid and note that
the potentiometer must be oriented as
shown, so it fits beside the mains rated capacitor on the PCB. Fit the knob;
you may need to lift out the knob cap
with a hobby knife and re-orient the
cap so its pointer position matches the
rotation marks on the panel. Apply a
smear of heatsink compound to the
underside of the Triac before installing the PCB inside the case.
Connect the Earth wires to M4
crimp or solder eyelets and cover with
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green heatshrink tubing. The eyelets
attach to the side of the case and the
lid using an M4 screw, star washer
and nut.
IC1 can now be plugged in, taking
care it is oriented correctly. Insert the
10A fuse into its holder. Press the cover onto the terminal barrier (CON1) to
prevent accidental contact.
Check your construction carefully
and especially check that the Earth
wires (green/yellow striped) actually
are connected to the case and Earth
pins on the mains plug and socket.
Check this with a multimeter set to
read low ohms. The cable glands need
to be tightened to hold the mains cords
in place.
Because these are easily undone,
the thread of the glands should have a
drop of Super Glue (cyanoacrylate) applied to the threads before tightening.
This way, the glands cannot be easily
undone. Attach the lid using the four
screws supplied with the case.
If you fitted the pin header for JP1,
now plug the shorting block into the
percentage (%) position. Connect a
heater to the controller and with the lid
in place, apply power and check that
the power can be varied using VR1.
The following text only applies to
the temperature-control version, so if
you built this, unplug the unit, open
up the lid and shift the shorting block
into the alternative position.
Setting up the thermopile
The reference voltage needs to be
adjusted now and this procedure also
compensates for any offset voltages
present in TS1 and IC2.
Do not plug the unit into the mains
directly during this procedure! You
will need a supply that is between 5
and 9V DC, (eg, a 9V battery) connected between the 0V PC stake and the
V+ PC stake on the PCB.
Monitor the thermopile voltage using a multimeter connected to the 0V
(black) and Thp (red) terminals, then
adjust VR2 so that the voltage at Thp
is half the voltage measured at the terminal that’s labelled 5.1V. So for example, if the supply is 5.1V, Thp should
be set to 2.55V.
This adjustment must be done when
the thermopile is measuring the same
temperature as its own body. To ensure
this, place a matte black object larger
than the diameter of the lens directly
in front of it.
This object needs to be the same
temperature as the sensor, so place it
nearby and leave it for an hour or so,
to ensure that they are very close in
temperature.
This black body can be a block of
wood painted matte black, the side of a
black plugpack, a piece of matte acrylic, black-handled kitchen utensil, etc.
Final calibration
Final calibration is done with the
unit powered from the mains, so make
sure the lid is in place.
Firstly, measure the ambient temperature with a thermometer and set
VR1 to that setting, noting that calibration can only be done if the ambient
temperature is within the range of 1531°C. Switch on the power and after
about five seconds, check if the load
is on or off. An incandescent lamp
Close-up view of the mains input and output section of the Heater Controller.
Don’t forget to place the protective shroud over the mains terminal block.
Celebrating 30 Years
April 2018 23
makes a suitable load (and you can
see if it’s on!).
Calibration is made by adjusting
VR2 but this adjustment must be done
only after power is switched off. So
the adjustment will be a trial and error procedure.
VR2 needs to be adjusted clockwise
if the load does not switch off when
VR1 is set to just under ambient temperature. Adjust VR2 anticlockwise if
the load is still off with VR1 set to ambient temperature.
During this procedure, ensure that
the lens is not blocked and has a good
view of the room and is not pointed at
a large window, oven, fridge, air conditioner or another source of heat/cold.
Temperature control mode
When using the Heater Controller as
a thermostat, the thermopile will need
to be placed so that the room temperature can be monitored.
This room temperature is best detected by using a non-shiny black object placed near the thermopile lens.
The object should absorb the surrounding heat from the room air, allowing
the thermopile to take the temperature reading.
In practice, you may just need to
place the controller box and lens near
to any object of any colour to have satisfactory temperature control.
The acceptance angle to the thermopile via the lens is about 84°. This can
be visualised as a cone projecting out
24
Silicon Chip
Fig.5: drilling and cutting templates for the diecast aluminium box and lid. The
“D”-shaped fuseholder hole should be drilled to 11mm and then filed to the
shape shown here, to prevent the fuseholder from rotating.
from the lens with an 84° angle at the
base. This is close enough to 90° that
100mm from the lens, the area that is
observed by the thermopile is a circle
of 200mm diameter. In other words, it
is a 1:2 ratio of the distance from the
lens to the spot size.
Celebrating 30 Years
Take care not to have the thermopile
facing the heater itself. The high infrared level from the heater will cause
the controller to switch off the heater.
Bar radiator elements can reach 380°C,
while convection heaters will be significantly above ambient.
SC
siliconchip.com.au
siliconchip.com.au
Celebrating 30 Years
April 2018 25
Three-Axis
Arduino
Seismograph
By Tim Blythman and
Nicholas Vinen
This “helichart” from a
Seismograph operated by the
US Geologic Survey (USGS)
shows a magnitude 6 earthquake recorded at Guam on
February 13th, 2018.
One of the disadvantages
of this format is that large
tremors cause the pen to
overwrite other data.
T
he Seismograph projects we
have published in the past involved building a horizontal
pendulum and then sensing its
motion.
However, pendulum designs only
respond to waves in one of the horizontal axes and so their sensitivity will
vary, depending on where the epicentre of the quake is located, compared
to your location.
Waves which are orientated along
the pendulum would barely register at
all. It can also miss vertical waves, such as
the S-wave and
Rayleigh waves.
(For an explanation of
earthquake wave
types, see the
desctiption in last
month’s Earthquake
Warning Alarm – siliconchip.com.
au/Article/10994).
In contrast, the 3-axis accelerometer
used in this project will pick up vibration with any orientation: up/down,
forward/back or side-to-side.
26
Silicon Chip
Using a sensitive three-axis accelerometer
to log seismic activity over long periods,
this Seismograph allows you to detect and
analyse distant or close earthquakes.
It’s a great educational project, easy and
cheap to build and it logs seismic activity
in all three axes, along with the overall
magnitude, to a microSD card.
So you won’t miss any waves which
happen to pass by and you can even
determine the type of waves later while
examining the data, based on the relative amplitude picked up by each axis.
This one is also much easier to build
because it’s completely electronic. Another big advantage of this Seismograph, besides its low cost is that it’s
a stand-alone unit and so don’t need
your PC to log the data.
Totally unattended, it can log
seismic data for days, weeks or
even months, and you can simply unplug the SD card any time and load the
data onto your PC for analysis when
it’s convenient.
This is the second Earthquake monitoring project we have published that
uses a 3-axis accelerometer. It is a development from the previously mentioned Earthquake Early Warning
Alarm project published in our March
2018 issue.
This incorporates both alarm
and logging functions in a single unit.
How it works
The 3-axis
Arduino
seismograph
can be built from
the Earthquake Warning
Alarm (March 2018) with
just a few extra parts.
Celebrating 30 Years
The Earthquake Warning Alarm used an Arduino with an MPU6050 accelerometer/
gyroscope module
to detect either Pwaves (which have
a horizontal component) or S-waves
(which have a vertical component). When
that unit detects a P-wave,
it flashes a LED and sounds a
siliconchip.com.au
siren, giving warning about the possibly imminent arrival of the more destructive S-wave and surface waves.
There are many thousands of earthquakes every year – between 12,000
and 14,000 according to reliable data.
But unless you hear about them on
the news, you will probably not even
be aware of them.
However, they can be detected and
you can get some idea of the distance,
magnitude and depth of the quake,
based on the faint vibrations that you
can pick up at your location.
If you want to study the details of
a seismic event after it happens, you
will need to record even the faintest vibrations and also the time they arrive.
It turns out that this can be done with
the same Arduino and MPU-6050 combination we used for the Early Warning Alarm. We just need to add an SD
card module to store the data and a
real time clock (RTC) module to provide accurate time-stamps.
Recording the data
A helichart Seismogram being recorded at the Weston Observatory in
Massachusetts, USA. Note how the arc within which the pen moves causes
distortion of the larger amplitude tremors. Image credit: Wikipedia user Z22.
In researching this project, it was
surprisingly difficult to find a stand- view all the axes at the same time, to files can have multiple channels and
ard data format for recording and see how the vibrations at different ori- they log data sampled at evenly-spaced
viewing raw seismic data with multi- entations correspond.
time intervals too.
ple channels.
We eventually managed to find some
So why couldn’t we store and proThese days, with MEMS acceler- software which could handle this type
cess seismic data as if it’s simply lowometer chips being readily available, of file but it only seemed to be intend- frequency audio data?
more and more seismographs log data ed to process seismic data, not view
If you think about it, that’s pretty
in multiple axes – so it would be logi- it. The commonly available viewers much what it is and this is one reacal to standardise on a suitable storage mostly show just one seismic plot at son why earthquakes can involve a
format. Yet this does not seem to have a time and that just isn’t adequate for lot of noise!
happened.
the task, in our opinion.
We considered storing the data as
You may recall seeing images of the
a .csv (comma separated value) file,
old-fashioned drum type seismographs Oh, the Audacity!
which is easy to analyse but the sheer
which use a pen and weight to log seisHowever, we did find one piece of quantity of data involved in logging day
mic data onto a roll of paper.
software – Audacity – that despite after day would make this awkward.
Sometimes, three of these machines not loading specialised seismic data
would be placed in the same location file formats, would open audio (WAV) Viewing seismic data
but with different orientations, to cap- files.
The output of a seismograph is
ture all the components of seismic acAnd that gave us an idea. Audio known as a seismogram and traditiontivity, much like
ally, this was in the form
we are doing with
of a helichart.
the three-axis acThis is an abbreviacelerometer.
tion for helical chart
Sensor type: ................................ 3-axis, 16-bit accelerometer
But when storand derives from the fact
Full-scale measurement: ........... ±4g
ing the data digitalthat the chart would be
Resolution: ................................... 0.000122g
ly, it makes sense
wrapped around a roto store it in a sintating drum, while the
Practical minimum reading:...... around ±0.001g
gle file, stamped
recording pen moves
Frequency response:.................. 0.625 (-3dB) to 21Hz (Nyquist limit)
with the time and
slowly along the chart in
Sampling rate:.............................. 42Hz
date that the rea 24-hour period, taking
File format:.................................... WAV, four channels
cording started.
a helical path.
That way, all the
A traditional helichStorage medium:......................... microSD card, up to 32GB
data can be copied
art seismogram is shown
Data rate:....................................... 1.2MB/hour, 29MB/day, 10.6GB per year
or moved as one
above. This appears as a
Maximum recording time:.......... 512 days
unit and you can
series of lines across the
SPECIFICATIONS
siliconchip.com.au
Celebrating 30 Years
April 2018 27
Fig.1: the Arduino (MOD1) senses vibration by
reading data from accelerometer MOD2, then logs the
acceleration readings onto an SD card using MOD4.
The real-time clock, MOD3, allows you to determine
what time the data was recorded, so you can time
stamp any tremors that were picked up.
page when removed from the recording drum. Seismic activity appeared
as wiggles in those lines.
Nowadays, the helichart is generated by a computer, and the lines are
horizontal rather than sloping.
So, that brings us back to the .wav
file format and Audacity.
Although designed for sound, it is
well suited to any sort of data that can
be represented as a waveform. Typical
wave files will be one or two channels
(ie, mono or stereo), but the .wav format can theoretically support thousands of channels.
As mentioned above, we’re using
four channels to record our data: separate X, Y and Z channels and a combined magnitude of all channels.
Its display is much like that of a helichart. Some other applications may
not handle .wav files with more than
two stereo channels but we found Audacity handles them well.
You could play the file back as audio
but the sound is not very interesting.
Unless a seismic event is very close (ie,
close enough for you to feel), you will
need to amplify the data greatly to get
anything remotely audible, and given
the low frequencies involved, you will
probably have to speed it up as well.
But what Audacity does very well
is let you view the data, scroll around
and zoom in to view events. Audacity
28
Silicon Chip
also shows a time scale at the top of
its window, so determining the time
at which a given event was recorded
is straightforward (see Fig.4).
You can also easily cut out an interesting section of data and save it into a
separate file for further analysis later.
Circuit details
The circuit diagram of the Seismograph is shown above.
The MPU-6050 Accelerometer module (MOD2) communicates with the
Arduino (MOD1) via an I2C bus, using
the SDA (data) and SCL (clock) pins.
The micro sends set-up commands
and then periodically retrieves acceleration readings over this bus. MOD2
runs off the same 5V supply as the
Arduino.
In contrast, SD card module MOD3
is wired up to the SPI interface on the
Arduino, which is on pins D10-D13
while the real-time clock module,
MOD4, connects to the same I2C interface as the accelerometer (MOD2),
ie, the SDA and SCL pins.
Because the SDA and SCL functions
on the Uno are shared with analog
pins A4 and A5, you can’t use these as
analog inputs when you’re using I2C.
You may be wondering why there is
a 4.7kΩ pull-up resistor from the ADO
pin on MOD2 to +5V. If you look at
our Earthquake Early Warning alarm
Celebrating 30 Years
circuit in March 2018, it did not have
this resistor.
But when we built our first prototype, we were mystified to find that
as soon as we had wired up the RTC
module, the accelerometer/gyro module stopped giving valid data. This was
even before we’d added any new code
to query the RTC module.
We spent quite a while troubleshooting before deciding to check
the default I2C addresses of these two
modules.
Surely, out of the 127 possible addresses, they would not have chosen
the same one? The DS3231’s address
is fixed at 68 hexadecimal. So we
looked up the MPU-6050 default address. Hard to believe but it’s true – it
was 68 hex too.
Luckily, the MPU-6050 does give
you the option to change the address to
69 hex, by pulling the ADO line high.
So that’s why we added the 4.7kΩ
resistor in this way; to allow the two
units to share the sole I2C bus that the
Arduino provides.
Another small change we had to
make was to change the pin controlling the alarm LED and siren from D12
to D7, as using D12 interferes with the
SPI bus on the SD card.
If you’re building this project as a
seismograph and you don’t need the
alarm function, you can leave these
siliconchip.com.au
A data-logging shield incorporates the
RTC module and SD card
socket, giving a compact
layout.
the Arduino code is checking the serial port for user input. This is because
we’ve incorporated a function to set
the date and time manually over the
serial console.
This allows you to ensure the real-time clock is set properly, so your
logged data will be accurately timestamped.
If at any time an SD card fault is
detected, the routine stops and LED2
flashes.
You will need to correct the fault
(eg, insert a fresh and empty microSD
card) and press the Arduino reset button to resume logging.
Similarly, to remove the card, press
S2, remove the card, then insert a new
card and press the reset button to resume logging.
Construction
components off but they’re inexpensive so we figured it was worthwhile
to leave them in.
We’ve also added a second LED
(LED2) to give status information about
SD card errors which would stop data
being recorded. It’s pulsed on briefly
when writing to the SD card, to give a
visual indication that the unit is working. It’s driven by digital output D5.
Note that we also briefly pulse LED1
if LED2 is flashing to indicate an error
writing to the card, for example, if it’s
full. This results in a periodic chirp
from the siren, alerting you to the fact
that the unit needs attention.
There’s also tactile push-button S2,
sensed by digital input pin D4, which
you can use to stop logging to the SD
card. You can then safely remove it
without corrupting the data.
In operation, the Uno reads the acceleration data from MOD2, runs it
through the filtering algorithm (to remove the force of gravity and so on)
and after reading the current time from
RTC MOD3, saves the data and time
to the SD card using MOD4.
The data saved in the file is the separate X, Y and Z accelerations in units
of g and also an overall acceleration
magnitude which is computed using
an RMS algorithm.
The time and date are stored in the
file name of the WAV file itself. A new
file is created at midnight and its file
name will contain the date. When you
open the file in a program like Audacity and are viewing the data, because it
displays the time from the start of the
siliconchip.com.au
file, this will correspond to the time
that the data was recorded.
Having written the data to the SD
card, the Uno then checks the filtered
acceleration values to check if a Pwave or S-wave has been detected,
and activates the alarm as necessary.
The cycle is repeated 42 times per
second but writes do not necessarily
occur to the SD card this frequently.
Rather, they are buffered and flushed
once per second, so you can expect
about 2-3 block writes per second to
occur.
At the same time as it’s logging data,
There are two ways you can put it
together. We’ve tested both approaches
and they give the same result.
The first method is the same as used
in the Earthquake Warning Alarm and
that is to solder the three separate modules (MOD2, MOD3 and MOD4) to a
prototyping shield and then plug this
into the main Arduino Uno (or compatible) board – see below.
The other approach is to use a data
logging shield like the Jaycar XC4536
or Altronics Z6380. These shields already have the RTC module and SD
card module built in. They also have
a prototyping area where you can sol-
One other option for building
the unit is to add separate SD
card and RTC modules to the
Earthquake Early Warning
Alarm (from last month).
Celebrating 30 Years
April 2018 29
D13 and CS to D10.
Ideally, MOD4 should be placed as
near these pins as possible to keep the
wires short. The SPI interface needs
to run very fast, and you may get issues with the SD card if the wires are
too long.
The final assembly step is to reconnect the assembled board to MOD1.
Building it from scratch
Again shown larger than life size, this photo of the back of the data logging
shield PCB shows where the wire links and single 470Ω resistor are located.
der the remaining parts.
The latter solution is probably simpler, but the DS1337 RTC used in
these shields is not quite as good a
the DS3231 real-time clock module.
And depending on where you get
the parts, it may end up costing more
(although probably not by very much).
If you have already built the Earthquake Early Warning Alarm, to add
the extra functions, detach the protoboard from your Arduino and move
the 91Ω resistor from pin D12 to D7,
to free up the SPI pins. Then add the
4.7kΩ between the ADO and VCC pins
of MOD2.
Now you need to add red LED2, its
current-limiting resistor, push-button
S2 and modules MOD3 and MOD4.
Connect LED2’s anode to pin D5 and
then solder the 470Ω resistor between
its cathode and GND. We used the
large GND strip in the corner of the
protoboard.
Tactile switch S2 is connected be-
tween pin D4 and GND, again using
the large GND strip. Make sure you
use the right pair of pins since some
of the pins will be permanently connected internally. Use a DMM set on
continuity mode to check which pins
are shorted when the button is pressed.
The two new modules are added
last. MOD3, the RTC module, can be
conveniently placed near the I2C pins
on A4 and A5, which avoids piggybacking wires onto the existing connections for MOD2. This is possible
because on an Arduino Uno board, A4
is connected to SDA and A5 is connected to SCL, so these pins have the
same function.
The connections for MOD3 are similar to those for MOD2: 5V to VCC, GND
to GND, A4 to SDA and A5 to SCL.
MOD4 is connected to the power
rails and SPI pins, with D10 being
used as CS/SS (chip select/slave select). Connect VCC to 5V, GND to GND,
MOSI to D11, MISO to D12, SCK to
If you’re building the Seismograph
using separate modules on a protoboard, use the following instructions.
Otherwise, jump to the section below
titled “Using a data logger shield”.
Start by soldering the three modules onto the protoboard, near the pins
which they need to connect to. Refer
to our photos and the circuit diagram
to determine where they should go.
You will need to solder the supplied
8-pin header to the MPU-6050 accelerometer board.
You can solder an 8-pin female socket to the protoboard to make it easily
removable, or simply solder the other
end of the header to the shield.
Solder the 4.7kΩ resistor adjacent to
the header for MOD2, between the VCC
and ADO pins, then connect it to those
pins. Use zero ohm resistors or wire
links to connect the four main pins of
MOD2 to the Arduino pins: VCC to
+5V, GND to GND, SCL to either A5
or SCL and SDA to either A4 or SDA.
If you want to retain the Early Warning Alarm function, you will need sensitivity adjustment trimpot VR1.
This can be soldered directly next
to the A0/A1/A2 pins and then wired
up to those pins in the most direct
manner.
To retain the alarm function, you
will also need to wire the piezo siren
up to the board, either by soldering its
leads directly or via a plug and socket.
Wire the positive lead directly to the
VIN pin on the Arduino
Previous Seismograph and Earthquake related articles
Build your own Seismograph
by Dave Dobeson. September 2005 –
siliconchip.com.au/Article/3173
Revised Seismograph
by Dave Dobeson. February 2013 –
siliconchip.com.au/Article/2364
Earthquake Early Warning Alarm
by Allan Linton-Smith and Nicholas
Vinen. March 2018 – siliconchip.com.
au/Article/10994
30
Silicon Chip
We’ve come a long way since the seismograph featured in our
Septembter 2005 issue: yes, it worked well but involved quite a
deal of mechanical work. Now, with a 3-axis accelerometer
and Arduino UNO, you can build a seismograph that
works in all three directions and allows you to examine
the various earthquake waveforms in detail.
And the best part? It costs
very little to build –
particularly if you
already have the
Arduino UNO!
Celebrating 30 Years
siliconchip.com.au
and the negative lead to the collector of
Q1; the bottom of Fig.1 shows which
pins of Q1 are which. Wire the emitter of Q1 to a convenient GND point.
Next, solder the cathode of blue
LED1 to the central (base) pin of Q1
and then solder its anode to a 91Ω resistor, with the other end to Arduino
pin D7.
Now follow the steps listed above,
immediately under the Construction
heading, to fit the remaining components which are unique to this design.
Using a data logger shield
The data logging shield version
of the Arduino Based Seismograph
is probably an easier way to build
this unit from scratch, as MOD3 and
MOD4, along with red LED2, are already on-board.
Start by adding a wire link (eg, a resistor lead off-cut) between the pins
marked 5 and L1. This connects the
on-board LED and series current-limiting resistor to pin D5 on the Uno.
Solder one leg of the 91Ω resistor from
pin D7 to the anode of LED1, then
connect LED1’s cathode to Q1’s base
(middle pin).
This can be done by placing the
components near each other as shown
in the photos, and trimming the legs
slightly longer than necessary. The
legs can then be bent until touching
and soldered together.
The next few connections should
be made with some short lengths of
insulated wire, and we found it easier
to run the wire underneath the shield.
The emitter of Q1 is connected to GND,
and its collector to the siren’s negative
lead (or to a polarised plug for the siren, if fitted).
The siren’s positive lead is connected to the shield’s 5V supply.
If you are using a siren which can
run from more than 5V, this can be taken to VIN instead, which is fed from
the DC jack on the Uno.
The tactile switch is mounted next
and it will need to be right against the
edge of the prototyping area on the
shield to allow space for MOD2. Connect one side of the switch to GND and
the other to D4.
Fit MOD2 next. We used a short
length of female header strip to make
the module removable and this also
allows it to easily clear LED1 and Q1.
You could solder it directly to the
shield if you have space. Regardless,
place the accelerometer assembly on
siliconchip.com.au
Parts list – Arduino 3-Axis Seismograph
1 Arduino Uno or compatible board (MOD1)
1 Arduino data logging shield (LED2/MOD3/MOD4) [Jaycar XC4536 or Altronics
Z6380] or see below
1 MPU-6050 based accelerometer/gyroscope module (MOD2) [Altronics Z6324]
1 small plastic box (eg, UB5 Jiffy box; optional)
1 1-13V loud piezo siren [Altronics S6115]
1 100kΩ mini horizontal trimpot (VR1)
1 2-pin polarised header and matching plug (CON1; optional)
1 USB power source (eg, USB charger or computer with free USB port)
a few short lengths of light-duty hookup wire
Semiconductors
1 5mm blue LED (LED1)
1 BC337 NPN transistor (Q1)
Resistors (.25W, 1%)
1 91Ω
(code white brown black brown or white brown black gold brown)
1 4.7kΩ
(code yellow violet red brown or yellow violet black brown brown)
Additional parts if not using data logging shield
1 Arduino prototyping shield
1 5mm red LED (LED2)
1 DS3231 real-time clock and calendar module and button cell (MOD3)
[SILICON CHIP Online Shop Cat SC3519]
1 microSD card interface module (MOD4) [SILICON CHIP Online Shop Cat SC4019)
the board before soldering, to check
that everything will fit.
Use short lengths of wire to connect MOD2 to the shield, with VCC
to 5V, GND to GND, SDA to SDA and
SCL to SCL.
There’s a small pad with these
four connections in one corner of the
shield, which makes these connections tidy. The only thing to watch
is that SDA and SCL are reversed between the two, so these wires will
have to cross.
Now add the 4.7kΩ resistor between
ADO and VCC on MOD2. The final
component is trimpot VR1, which
neatly slots into the pads for A0 and
A2. Use a wire link to connect the middle leg to A1.
Now double check all the wiring and
Fig.2: the output from the serial monitor showing normal data display, along
with the time and date being set. Time setting mode is entered by pressing the
“~” key.
Celebrating 30 Years
April 2018 31
This straight-on view of the protoboard shows the location of the various
components and connections. This is a little different from the board shown
last month as it also has the microSD card adaptor module (centre top) and the
DS3231 RTC module (lower right), both mounted vertically to the protoboard.
plug the assembled shield into MOD1
(the Arduino Uno board).
Programming it
If you haven’t already done so,
download and install the Arduino
IDE from www.arduino.cc/en/main/
software There are a number of libraries that need to be installed to support
the RTC module and SD card module.
Two of these are easily added by the
Library Manager feature, which is only
available from IDE version 1.6.4 but
we will also supply them in the software download package (as ZIP files).
If you don’t have this version, unzip the three library folders into your
Arduino libraries folder. This is usually found in your Documents folder,
under Arduino/libraries. You may
need to restart the IDE after adding
the new libraries, but this usually is
not necessary.
To use the Library Manager, go to
Sketch Include Libraries Manage Libraries and search for “rtclib”,
click the version by “Adafruit” and
click install (see Fig.3). Do the same
for “SdFat” and install the version by
Bill Greiman.
With the libraries installed, open
the sketch file, connect the Uno to the
computer via a USB cable and click
Sketch Upload.
If the compile and upload do not
complete successfully, check that the
libraries are in the correct place and
properly installed. Also, check that
you have the correct COM port selected in the Tools menu.
Now open the Serial Monitor (Tools
Serial Monitor or Ctrl-Shift-M)
and check that the baud rate is set to
115200. This will give detailed error
messages if there are problems and also
allow you to set the time accurately.
Set-up
You might notice that the red LED
is flashing in groups of two. This is
because it has not been able to detect
the card (presumably, you have not inserted it yet). Disconnect the Uno from
the computer and install an SD card
or microSD card as appropriate. The
card should be formatted with FAT16
or FAT32. Re-connect the Uno and restart the Serial Monitor.
If the Serial Monitor is showing a
Fig.3: using the Library Manager makes installing libraries straightforward. Here we are installing the library for the RTC
module. The procedure is similar for the SdFat library
32
Silicon Chip
Celebrating 30 Years
siliconchip.com.au
stream of |XY| and |Z| values, like
that shown in Fig.2, then everything is
working as it should be. The blue LED
should light up if the unit is picked
up and shaken, and you should also
see the values in the Serial Monitor
change. Now is a good time to adjust
the alarm sensitivity.
Clockwise on VR1 is more sensitive, so turn VR1 fully clockwise then
turn it slowly back until the blue LED
just stays off (remembering the alarm
condition persists for a few seconds
when triggered).
If you find the red LED is still flashing, count the number of flashes in
each group. If you are getting one flash
at a time, the Uno could not detect the
RTC module. Check that the wiring to
the RTC module is correct. Any more
than that indicates a problem with
the SD card.
If you are getting two flashes and the
card is installed, check the wiring to
MOD4. If you are getting three or more
flashes, the card is being detected but
cannot be written to. This may be a
corrupted or full card.
We’ve found that the unit generates
about 30MB of data per day, so even
a 1GB card will last a month without
filling up.
FAT16 has a restriction of 512 directory entries, which should give over a
year of operation.
Using it
When you want to remove the SD
card to examine the logged data, press
tactile switch S2 and the red LED will
light continuously. This indicates
that the SD card has been shut down
safely and the Seismograph can be
powered down without corrupting or
losing data. If you are simply changing to another card, you can remove
the old card, insert a new card, then
press the Arduino reset button to resume logging.
The files are stamped with the date
and time that logging started and a new
file is created at midnight.
As mentioned above, you can set the
time and date via the Serial Monitor.
This is done by sending a ‘~’ character to the Uno, which will cause it to
pause logging and wait for an input.
The input is of the form YYMMDDHHMMSS, and should just be digits. For
example, for 3:30pm on March 15th,
2018, enter 180315153000. Remember
that you have to press ‘Enter’ for the Arduino Serial Monitor to send the data.
siliconchip.com.au
The simplest method is to uncheck
the “Autoscroll” option on the Serial
monitor, then type ~ and press enter.
Type the twelve digits for the time and
date and press enter as soon as the actual time matches exactly what you
have entered.
You should see a message that the
time has been changed and a new file
is created starting at the current time.
See Fig.2 for an example of this.
Locating the unit
The seismograph can be fitted in an
appropriately-sized Jiffy box if desired
or it can be operated as-is.
But it should be mounted somewhere solid, away from doors and not
on top of a desk or other piece of furniture which can either be bumped or
will easily transmit footsteps, vibrations from traffic or other non-seismic
sources of vibration.
Perhaps the best place for it would
be on top of a concrete slab in a basement. If you don’t have a basement, it
could be mounted on a solid groundfloor wall (away from doorways) or
kept on the floor in an out-of-the-way
place (eg, a closet).
This will maximise seismic pickup
while minimising other sources of vibration.
On the other hand, maybe you’re
interested in seeing artificial sources
of vibration, such as passing traffic, in
which case you may want to deliberately mount the unit near a road. It’s
up to you!
Try to avoid placing it on any soft
surfaces which might absorb seismic
energy, such as carpet or vinyl flooring.
Viewing the files using Audacity
Audacity is available as a free download from www.audacityteam.org/
download/ The WAV files created by
the Seismograph have four channels
and can be viewed (and even played)
in Audacity. Note that under normal
circumstances, the data will simply
look like a flat line unless you amplify it since if the unit is picking
up any tremors, they are likely to be
quite weak.
We actually couldn’t see any activity at all until we amplified the waveforms by 20dB, after which we could
see movement starting about the time
we came into the office in the morning (truck traffic on the nearby road
would have increased at around the
same time).
Celebrating 30 Years
April 2018 33
Fig.4: a Seismogram displayed in Audacity. Note the time code along the top of the window. The unit was shaken three
times and you can see how the movement was picked up by different combinations of the three axes. The first shake was
side-to-side, the second forward/back and the third up/down. All register in the bottom (combined) trace.
Note that Audacity will display the
traces with a vertical scale from -1.0
to +1.0 while the data actually represents g-forces of -4.0 to +4.0. So you
will need to multiply any readings
taken off the vertical scale by a factor
of four, to convert them to gs. By the
way, we suggest after opening the WAV
file, you use the View Fit Vertically
option (CTRL+SHIFT+F) to expand
the display.
The first channel, normally labelled
“Left”, is actually the X-axis reading from the accelerometer, while the
second “Right” channel is the Y-axis.
A small diagram printed on the top of
the Altronics Z6324 module indicates
the orientation of the X-axis, with the
arrow pointing towards in direction of
acceleration which will result in positive readings. Similarly, the Y-axis is
shown on the board.
The Z-axis is the third channel, by
34
Silicon Chip
default labelled “Mono” and indicates
up-down motion of the accelerometer, with forces pushing it down being positive (ie, in the same direction
as gravity).
Since the fourth “channel” of the
recording (also labelled “Mono”) constitutes the magnitude of the threedimensional force vector, that means
it is effectively rectified, ie, the value
shown will always be between 0 and
1, corresponding to a force of between
0 and 4g. The advantage of this data is
that it’s guaranteed to pick up vibrations regardless of their orientation
relative to the unit.
If you see anything interesting in
the plot and want to zoom in and examine it, all you need to do is move
your mouse cursor over that area, hold
down the CTRL key and rotate your
scroll wheel up.
It will zoom in and expand that
Celebrating 30 Years
section of the recording. Rotating the
scroll wheel in the opposite direction
will allow you to zoom back out.
We suggest initially, you use the
USGS Earthquake map at https://earthquake.usgs.gov/earthquakes/map/ to
locate recent earthquakes in your part
of the globe and then estimate when
they would have arrived at your location, based on a speed of around
3-8km/s.
You can then check your seismogram
files to see if you picked up the tremors.
If you can’t see anything, try amplifying the signal in a 30-minute window
surrounding that time by successively
large dB values (by dragging a selection
over that time period and using the Effect Amplify menu option) until you
can see the tremors.
Once you’ve found a few earthquakes in this manner, you will know
what to look for in future.
SC
siliconchip.com.au
Review by Nicholas Vinen
Rohde & Schwarz RTM3004
Mixed Signal Oscilloscope
Until recently, unless you had a lot of money to spend, you had to decide
whether you wanted a scope with good vertical resolution and low noise
(for examining low-level signals) or high-speed performance (for highfrequency or rapidly changing signals). Now you can have both, with the
Rohde & Schwarz RTM3004.
I
f you have seen the recent ads from
Rohde & Schwarz, you will have noticed that they have released a number
of new scopes and that most of them
share a single distinguishing feature:
their use of a 10-bit analog-to-digital
converter (ADC) for better vertical
resolution.
Typical digital scopes use an 8-bit
high-speed ADC. That means they
can sense 28 or 256 different voltage
levels in any given range. The 10-bit
ADC used in many of the latest Rohde
36
Silicon Chip
& Schwarz scopes has 1024 distinct
voltage steps – a significant increase.
This is especially useful when you
consider that your standard highbandwidth oscilloscope probe has a
10:1 division ratio. This is necessary
to allow the probe to be properly compensated so that it has a reasonably flat
frequency response up to the scope's
-3dB point (ie, its rated bandwidth).
So if you're probing a 100mV signal
with the standard set of probes, you
get just 10mV at the input connector.
Celebrating 30 Years
If the original signal amplitude is already low and the scope has an 8-bit
ADC, you may get a very small “jagged” trace, so it can be difficult to make
out the shape of the signal. With a 10bit ADC, you have four times as many
steps and the waveform shape is much
clearer and cleaner, as you will notice
in our screen grabs.
However, a scope’s own noise is also
an issue when examining low-level
signals. The RTM3004 has a slightly
better-than-average noise level, so you
siliconchip.com.au
Fig.1: each trace shows one of the pattern generator outputs,
set to produce a rolling binary counter incremented at 10MHz.
Here you can see the five different bandwidth options that were
selectable for each channel of our 500MHz bandwidth demo
scope.
can often take advantage of the extra
vertical resolution. But sometimes the
noise still gets in the way.
Five different bandwidth limiting
options were provided on the 500MHz
model we tested, from 20MHz up to
the full 500MHz. That lets you choose
a good tradeoff between bandwidth
and noise, depending on the signal
you are measuring (see Fig.1). This is
a welcome feature.
In terms of waveform capture rate,
the RTM3004 compares well with its
competitors, handling up to 64,000
waveforms per second at up to five
gigasamples per second. It also has a
very large 40Mpoints per channel of
memory depth.
You can expand that to 80Mpoints
on the 4-channel model, if you're only
using two channels. That’s truly massive and you can capture data on a
long time-scale and then zoom right
in to see the details.
First impressions
Besides the high vertical resolution,
one of the first things we noticed when
switching on the scope is that coming
out of standby and into full operation
only takes about ten seconds; quite
a bit faster than some of the other
scopes we've used. It's also very quiet
during operation, with barely audible
fan noise.
Another nice feature of this scope
is the high-resolution touchscreen.
It's very sharp and clear and you can
see a lot of detail in the traces and labels. But it lacks an anti-glare coating,
so you can see your reflection on the
siliconchip.com.au
Fig.2: this demonstrates that you can have up to eight userconfigurable measurements at the bottom of the screen, in this
case, peak-to-peak voltage and frequency for each channel.
Colour coding helps easily identify which measurement is for
which channel.
screen, along with whatever happens
to be behind you (a window etc). That
can make it harder to make out the actual display. But if you use it in a dimly
lit room, it's very good.
This unit makes good use of the
large amount of screen space available on the 1280 x 800 pixel, 10-inch
(25cm) display.
Most of the screen is filled with the
graticule, giving the maximum amount
of space for traces. Menus pop out as
necessary but you can easily make
them disappear to get the screen real
estate back. The wide aspect works
well, giving twelve time divisions and
10 voltage divisions.
Measurements
The RTM3004 lets you put eight
measurements of your choice at the
bottom of the screen. Far better than
the four or five of most other scopes.
This may seem like a minor point
but when you’re using all four inputs,
it can be a godsend (see Fig.2). Measurements are chosen from a menu of
clear icons (Fig.3). It's a small thing
but it's one of our favourite features
of this scope.
A bonus measurement feature is
that each measurement can be "gated"
within a specified time period so that
the result only depends on the values
within that time period. The time period can be defined as any subset of
the 12 graticules shown on the display, based on either percentage or
time delay and each measurement can
be based either on the gating period or
the full screen.
Celebrating 30 Years
When using gating, a blue highlighted box appears behind the traces for
that period, so you can see how the
measurements relate to the traces on
the display (see Fig.4).
Illuminated buttons
The colour-changing illuminated
buttons on this scope are a great idea.
The vertical controls (voltage range,
etc) change colour to match the colour
coding of the currently selected channel. Similarly, the trigger source button colour matches the channel which
is currently being used as the trigger
source. Pressing that button cycles the
trigger source through the available
channels too.
But the default brightness of the illuminated buttons is quite dazzling.
Happily, the menus provide the ability
for you to adjust the button brightness.
And at the minimum setting of 20%,
they're a lot less dazzling in anything
but the most brightly lit workspace.
It's a pity that you can't turn them
down lower because a setting of 10%
would probably be ideal in our office.
At 20%, the contrast between the lit
and unlit buttons makes it hard to read
the labels on the unlit buttons.
Now, on any DSO, when you have
the trigger mode set to "normal" (not
"auto"), it's quite common for the scope
to stop triggering if the input signals
change. And if you had a steady signal
up to that point, it won’t be immediately obvious that the scope is no longer triggering and updating its screen.
But Rohde & Schwarz have added
a timer near the upper-right corner of
April 2018 37
Fig.3: one of four menus showing the available measurements.
The menu at right shows that you can select a measurement
position (1-8), measurement type (from the menu), source
channel, whether to use the gating period and whether to
display statistics (max/min/average).
the screen. When triggering normally,
this area reads "Trig" but if triggering
stops, it changes to read "Trig? 1s" and
the time counts up. So it’s obvious that
triggering has stopped and you can see
at a glance how long the display has
been static. It's a small feature but one
we found ourselves using quite often.
User interface
Overall, we'd have to say that the
user interface on this scope is probably
the easiest that we have used and is
very intuitive. That's largely because
Rohde & Schwarz have abandoned
the idea that all functions need to be
available via dedicated buttons and
you now need to use the touchscreen
for many operations.
Fig.4: any set of (or all) measurements can be “gated” by a time
period which is a subset of the current period being displayed
by the scope. This is the area shown in blue and it can be
defined as either a proportion of the display or by the start and
end delay, as shown here.
That means they were able to simplify the button layout and it also
makes it a lot more obvious how to
carry out most tasks. The tradeoff is
that you will probably need to clean
your fingerprints off the screen regularly. But that's a small amount of extra effort in exchange for making the
scope easier to use.
One more nice aspect of the interface is the "toolbar" at upper left, with
icons giving you access to commonly
used functions.
There's a small settings button at
top-middle which lets you select
which icons appear in this toolbar (see
Fig.5). This allows you to populate the
interface with buttons to features you
frequently use.
One small criticism that we have
of the user interface is that it has unnecessary animations when you press
buttons.
For example, the menu at the righthand side of the screen "slides" in and
out. That takes time and we’re often
ready to press a button before it's actually visible. It would be nice to have
the option to be able to turn off animations, to make the interface a bit
more snappy.
While the interface is quite responsive, there are occasions when there is
a short delay between pressing a control and having it take effect. It isn't
a big problem but it does fall slightly
short of our expectations for the responsiveness of a high-end scope.
The USB and Ethernet control sockets are on the back, plus power and an auxilliary output. The 16 digital inputs are on
the right side of the scope, which is convenient since it means the ribbon cables don’t get in the way in mixed signal mode.
38
Silicon Chip
Celebrating 30 Years
siliconchip.com.au
Fig.5: these icons can be displayed on the “toolbar” at upper
left so that you can select the option at any time. The currently
visible icons are shown in blue and as indicated on-screen, you
can have up to eight shown. This menu is accessed using the
button just above the yellow trigger marker.
Options
The RTM3004 has a number of extra cost software and hardware options
which can add features to the scope.
Besides the bandwidth (upgradeable to 1GHz) and 16-channel logic
analyser (MSO) option, these include
serial triggering and decoding for a
range of protocols, history and segmented memory, spectrum analysis,
power analysis and an arbitrary waveform/pattern generator.
The configuration menu for the pattern generator is shown in Fig.6. Some
of these options (eg, the pattern generator and power analysis) provide
built-in “apps” which can be launched
when needed.
A number of these options, including all the serial decoding/
Fig.6: configuration for the pattern generator option. Like most
aspects of the scope, when you’re adjusting its settings, the
menu pops out from the right-hand side of the screen. When
finished, it can be hidden simply by pressing the “menu” button
in the lower right-hand corner.
triggering options, history/segmented
memory, spectrum analysis, power
analysis and generators can be purchased in a bundle (RTM-PK1) which
costs a lot less than paying for each
option individually.
The pattern generator is quite useful, especially in combination with the
serial decoding and triggering options
as it can be used to generate serial test
data, eg, to send to a DAC. You could
then use the scope to observe the corresponding DAC output.
Other features
We don’t have space in this review
to list all the other features of the
scope. It has pretty much everything
else that you would expect (or can
think of, really).
It supports mask and limit testing,
segmented memory, digital voltmeter,
probe sensing, active probes, external
triggering and so on.
Check the Rohde & Schwarz website
for more information on the scope and
all its features (www.rohde-schwarz.
com/au/product/rtm3000).
Conclusion
If you are in the market for a fullyfeatured scope with a bandwidth up to
1GHz, the Rohde & Schwarz RTM3004
is well worth considering – especially if you’re keen to get an instrument
that’s easy to drive.
For more details, see the Rohde &
Schwarz Australia website at www.
rohde-schwarz.com/au/
For pricing or to order a scope,
phone (02) 8874 5100 or email sales.
SC
australia<at>rohde-schwarz.com
Features
•
•
•
•
•
•
•
•
•
siliconchip.com.au
10.1-inch 1280 x 800 touchscreen
display
Four analog and 16 optional
digital channels
Bandwidth: 100Mhz (upgradeable
to a maximum of 1GHz)
Sample rate: up to 5Gsamples/s
Memory depth: 40Mpoints/
channel and up to 80Mpoints
interleaved
Wafeform capture rate: 64000/s
500µV/div maximum sensitivity at
full bandwidth
10-bit ADC
Connections: LAN, USB, Ethernet
April 2018 39
SERVICEMAN'S LOG
Why can't I program MY alarm?
Dave Thompson*
Many moons ago, I wrote about an
alarm system I was having trouble with
at my then residence. I’d experienced
intermittent problems with it in the
final few months of its almost tenyear lifetime and it had finally
given up the ghost, which was a
real shame as it had been such
a good system.
Items Covered This Month
•
•
•
Bosch burglar alarm
Marantz SR870 receiver repair
Mitsubishi air conditioner
*Dave Thompson runs PC Anytime
in Christchurch, NZ.
Website: www.pcanytime.co.nz
Email: dave<at>pcanytime.co.nz
It had protected, without fault, a
couple of our dwellings with attached
workshops and had been disassembled and re-installed several times as
we’d moved from place to place in the
early days.
The problem with all electronic
hardware is that it is usually quickly
superseded and this alarm system was
no exception.
Of course, the alarm company who’d
originally installed it was more than
happy to pull it all out and replace it
with a shiny new version, with more
bells and whistles but apparently that
also meant changing all the sensors I’d
spent a considerable amount of time
and money on.
The sales guy was adamant they
were no longer compatible with newer
systems, a statement I viewed with
great suspicion. I was subsequently
vindicated when I learned that all my
sensors would have worked with any
new panel sourced from this company
(and probably dozens of others as well).
40
Silicon Chip
However, that deception aside, I
was not yet in a position to shell out
the amount of money they wanted
for a new system, especially as they’d
“given” us the old system as part of a
deal when we signed up to a monitoring contract with an affiliated security
company.
Back then, we got the basic system (which came with three standard
PIR sensors and a smoke alarm) if we
agreed to a two-year monitoring deal,
which was actually a win for both parties. We got a good quality, monitored
alarm system and they got a dollar
a day from us for a couple of years,
guaranteed.
From what the installers said as
they put the thing in, they had "sold"
a huge number of these package deals
and were run off their feet with installation work.
Unfortunately, now many years down
the track, that deal – or any others like it
– no longer exist, which is why I baulked
at the quoted cost of a new system.
Celebrating 30 Years
Before making any decisions, I
looked at all the alternatives. I wouldn’t
be much of a serviceman if I neglected
to do my due diligence!
The system we’d been using, the
Solution 6 + 6, was made by Bosch, a
company not known for making junk.
So although it was basic and essentially given away as a deal sweetener,
it was by no means a bottom-of-theline system.
We’d also added a whole bunch of
extra sensors to the "free" package, as
we also wanted to include our garage
and workshop, an altogether much
larger area than the standard package
was designed to cover.
Thus, we ended up with an array
of door and window switches, extra
smoke alarms and more PIR sensors,
with pet-safe versions of these detectors replacing the standard versions
that came with the package deal – all
at our expense, of course.
Overall, this system was rocksolid. I can only recall one instance of
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it going off with no apparent cause, the
dreaded false alarm.
Fortunately, it was in the middle of
the day and I was nearby, so no real
harm was done. Even though I knew
which zone and sensor was responsible, I never did figure out why it went
off and as it never happened again, I
didn’t lose too much sleep over it.
Newer isn't always better
In contrast to this, I have lost count
of the number of times the much newer
and far more sophisticated digital alarm
system (purchased from AliExpress) at
our new place has gone off over the last
18 months with no apparent trigger.
Like any electronic device, the more
complex it is, the more likely that it
will give problems. No doubt there is
a law named after some famous academic used to describe this phenomenon, but as I’m not aware of it yet I’ll
take a punt and call it "the Serviceman’s Law".
This new alarm system does have
several advantages over that old one
though. We now have features such
as wired/wireless sensor connections,
manual/keypad operation, RFID or
key-fob arm/disarm and both GSM
and copper-line connectivity for monitoring.
If required, I could use up to 99
sensors with the new system, while I
siliconchip.com.au
could wire in a maximum of only 12
with the old one (and even then, I’d
have to use some jiggery-pokery to
achieve that).
Still, that old system was highspec in its day, and as I said, it
hardly missed a beat until a few
months before it died.
As I wanted to keep using it at the
time, I’d needed to come up with an
alternative to total replacement, and
that meant finding a new main board,
or perhaps a whole new alarm panel,
which was a tough ask considering
the age of it.
As it turned out, I got very lucky.
On a local auction site, I found a
guy selling a brand-new panel and a
new, spare keypad for my exact system. He’d somehow ended up with
two panels and an extra keypad for a
job he was doing (I didn’t ask) and
now, a while after the fact, he was
cleaning out his garage and wanted
to be rid of it.
I was happy to part with a hundred bucks for the panel and keypad, which was a bargain considering what the alarm company wanted
for that new system.
The new panel included the steel
mounting box and power supply
board. All I had to do was disconnect
and remove the old box and then connect and mount the new one using the
same screw holes.
It was an easy task; I didn’t require
any diagrams or circuits as I just
swapped out sensor wires and resistors from where they were connected
on the old board to the corresponding
terminals on the new panel.
The most difficult and time-consuming part of the whole process was
programming the new board with all
our settings. This process also raised
an interesting philosophical issue. The
new main board had been pre-programmed by the alarm company who’d
imported it using their own unique installer code, which meant that I could
not fully program the alarm board as I
didn’t know the code; the seller didn’t
know it either.
There are two codes used in this
system, both of which have their own
levels of access to the system and its
various functions. The installer code
is used to program all the non-consumer related information into the
panel, such as telephone numbers for
remote monitoring, different options
for the various types of sensors, zone
Celebrating 30 Years
settings and other miscellaneous technical parameters.
Importantly, the alarm cannot be
armed or disarmed using the installer code, a necessary safeguard to help
prevent rogue installers going around
disabling alarm systems.
That said, installers can add "master" codes, which are used to disarm
systems, and they usually do so as a
service to the customer, mainly because most new alarm owners do not
have the desire to go poking into the
workings of the alarm system, nor do
they want to have to wade through the
manual in order to learn how to program in their own codes.
Those who are prepared to read the
instructions, or who are concerned
about others (namely the installers)
knowing their alarm codes are able
to create their own master codes, although this is about the only thing they
can do without requiring the installer
codes as well.
The main problem is that, for obvious reasons, the installer codes are
almost never released by the alarm
companies.
This raises the philosophical issue
I speak of; while it is fair enough for
installers to retain those codes if they
(or their affiliated monitoring company) have installed a "free" alarm
system along with a monitoring deal,
I bought and paid for this particular
panel outright, so surely I should be
privy to any and all codes and keys
used in the system.
Not knowing that installer code, severely limits what I can do with it, and
this is just not cricket. This would be
akin to me putting a BIOS or set-up
password on every computer I sold
and then charging a fee to anyone who
wanted to get into the BIOS to, for example, add another hard disk or alter
existing settings.
April 2018 41
To any right-thinking person, this
is not acceptable, and yet as far as I
can tell this is industry practice in the
alarm business.
There is a potential “back door”
though; the main logic board has a "set
default" button on it, which does exactly what you’d think it does, and that
is re-set any programmed settings back
to their factory defaults, including the
installer code and master codes. This
action can also be accomplished using
certain codes sent to the logic board
via any of the alarm keypads.
However, as always, there’s a gotcha
involved. There is an installer option
to protect that setting and this prevents the set default button or keypad
codes from being used to default the
system settings.
While the service/installer manual
specifically advises against using this
setting, as it requires the unit to be
sent back to an authorised agent for reprogramming (or in this case, requires
me to pay some guy to come out and
do it), this particular company chose
to ignore the instruction manual and
set that option to on, preventing me
from using it to default the settings.
Nice one.
I understand there are business and
security implications to this, however,
any bad guy would have to be pretty
clued up in order to go around accessing alarm systems and besides, it
would be a pretty obvious clue if the
alarm was disabled by someone other than the owner. Either way, in my
opinion, setting an installer code and
making it non-removable is not warranted, period.
In the end, I had to pay a couple of
likely lads to come out and remove
that installer code. They didn’t want
to do it, and certainly wouldn’t tell me
what the code was – not that it mattered; I neither needed nor wanted to
know it, I just wanted it defaulted –
but it turned out that they didn’t actually know it anyway.
However, I put my case in strong
terms that this was now my alarm
and as such, they or their colleagues
had no right to set any passwords or
codes into it that prevented me from
accessing any settings within it. After
a lot of back and forth and a few phone
calls to superiors and other installers,
they agreed to default the panel, trying all the codes they knew, including those used both past and present,
to default it.
They eventually chanced upon it
setting everything to default. Commenting that this code had not been
used for many years, they eventually
loosened up and showed me around
the programming side of things and
even demonstrated how to use a programmer board to make things easier,
and double-checked the option that
prevented the defaults from being set
was disabled.
In the end, we recognised we were
all servicemen and as such were kindred spirits. They knew I wouldn’t be
going around busting open alarm systems and were happy to share those
few tricks of their trade. I’ve engaged
them several times since to do alarmrelated work and it is nice to have a
connection to people with those specialist skills.
Well, that's one way to stop
it beeping
I bring the subject of this alarm
system up because last week the guy
who’d been renting our old place (the
one with the repaired system installed
in it) moved out.
When I went in to check the property out, I found he’d somehow disabled the alarm system; it was completely dead. When this bloke had
first moved in, he’d mentioned that
the alarm would be a welcome asset
as he had some expensive laser-cutting
equipment he wanted to set up in my
old workshop.
Obviously, something had changed
in the meantime, so I got in touch to
determine why the alarm was no longer working. He claimed that shortly after he moved in, it started displaying a
"mains" error on the keypads and because of this, the system beeped once
Servicing Stories Wanted
Do you have any good servicing stories that you would like to share in The Serviceman
column? If so, why not send those stories in to us?
We pay for all contributions published but please note that your material must
be original. Send your contribution by email to: editor<at>siliconchip.com.au
Please be sure to include your full name and address details.
42
Silicon Chip
Celebrating 30 Years
a minute, which it is designed to do.
Not knowing better, he’d climbed
up to where the main alarm panel is
located, opened the box and disconnected the mains connections and battery terminals, thus shutting the whole
thing down and killing the beep.
If he had called me, I could have
told him how to stop that beeping in
five seconds with the push of a keypad
button. However, he fancied himself a
bit of a DIYer and preferred to resolve
it himself in his own refreshingly nontechnical way.
I empathised though; that beep is
annoying. Every keypad has a piezo
buzzer, so any warnings are audibly
announced, along with flashing zone
LEDs, and in this case, the warning
would go on either until mains power
was restored or the battery went flat
(or someone physically unplugged it!).
During the quakes, we lost power
a lot, so I am intimately familiar with
that particular warning. Still, his response was a little heavy-handed, and
as it turns out, there were a few other
"command" decisions he’d made that
he wasn’t entitled to make as a tenant;
the alarm is just one example.
The first thing I had to do was dig
out the alarm’s service manual again.
With no power for over a year, I might
need to re-program it. I made my way
into the roof space and found the panel
door wide open and full of new residents.
A quick vacuum cleaned it all out
and I could then see he had simply
cut the wiring. Again, if he’d called I
could have told him where the master
switch was at ground level.
None-the-less I reconnected it all,
but when I flicked the mains switch
on, there was nothing, though when I
re-connected the battery leads, I heard
a beep and the keypads lit up with
fault indicators. At least the battery
was holding its charge; fortunately, I’d
replaced it not long before we moved
out so it was still fairly new.
However, the problem was still no
mains power. I broke out my line testing tools and worked backwards from
the panel through the system until
I discovered that the mains feed to
the panel was dead because this guy
had wired in an extractor fan for his
laser and had inadvertently killed
the alarm circuit, which caused the
mains fault.
He’d removed and taken the fan
away, so I used a junction box to re-consiliconchip.com.au
The Marantz receiver is tightly packed with components, making testing difficult.
nect the loose cables and with power
restored, the beeping stopped and the
fault cleared. All my settings had been
saved, but I changed all the codes anyway, just to be safe. Who knows, there
may be servicemen around who are not
as trustworthy as I am!
Marantz SR870 receiver repair
R. A., of Melbourne, Vic, recently
fixed his venerable Marantz SR870
Home Theatre Receiver. It has given
nearly 20 years of sterling service and
will now likely soldier on for another 20. The fault he discovered was all
too common and luckily, easily fixed.
Here’s his story...
While studying to be an engineer, I
worked as a serviceman and have dabbled in servicing ever since. Like all
servicemen, my own gear is the last
to be fixed. My 19-year-old Marantz
SR870 5.1 channel home theatre receiver had been playing up for well
over a year.
Every now and then, it would spontaneously power down then usually
quickly reset, sometimes repeating
the cycle then usually settling down.
Recently it played up more frequently
and now would sometimes not recover
at all for quite some time.
Eventually, I decided to do something about it. My initial thoughts were
to suspect a capacitor in the power
supply or maybe even a faulty fuse.
After removing the receiver from its
place in the system (no trivial task and
the reason for the procrastination), I
pulled the cover off and inspected the
power supply board.
Everything looked fine. No bulging
capacitors, the fuses looked rock solid
and were a quality type. The fault was
siliconchip.com.au
so intermittent that waiting for it to
fail on the test bench was an exercise
in frustration. It was clear to me that
all mains power was being lost when
it did fail, so I did the easy thing and
replaced the mains cord, which had
some very sharp bends in it where it
was clamped in several places.
Back in use, it worked well for about
24 hours – then failed again.
The receiver was packed full of
components (as shown by the photo
above), had been well built and was
in excellent condition, so I was loath
to start pulling out components on
a search-and-destroy mission. Even
measuring voltages was impossible on
some of those nested PCBs.
Instead, I looked on the internet for
clues but there was little information
available. However, I came upon a
YouTube clip where an American technician worked on a similar receiver.
The interesting thing was that there
were lots of comments below the video, none of which related to the video
but were asking all sorts of questions
regarding receivers and faults.
The small power input PCB from the
receiver.
Celebrating 30 Years
The technician replied to all comments with patience and much insight.
So, I took a chance and asked about my
SR870. Overnight he replied, saying
that there was a common problem due
to poor soldering on the power input
PCB. In particular, he said to check the
soldered joints on the small standby
transformer and regulator IC.
I retrieved the unit and opened it up
again, then removed the PCB in question (shown in the previous photo).
It was relatively easy to get the PCB
out; I just needed to remove the big
main transformer to give some wriggle room and also work out how to unclip each small connector. Only two
of the five used the same locking tab
arrangement.
Using reading glasses with three
times magnification, I discovered that
at least one soldered pin on the primary of the transformer looked dodgy. So
I took macro photos and then re-soldered every transformer pin and every
pin on the aforementioned IC and put
everything back together.
Cutting to the chase, this completely
fixed the fault. Later, looking at the
photos on a large monitor, it was obvious that all three of the primary pins
of the transformer, along one side, had
faulty soldered joints (see the photograph below). All the other joints
looked OK.
My theory is that a flawed mechanical design caused this issue. The
manufacturing process required the
transformer to be first soldered to the
PCB, then two long self-tapping screws
went through lugs on the transformer,
through the PCB, through a standoff,
to the chassis.
Tightening these screws forced the
transformer into the PCB and thus
placed strain on the solder joints.
I was happy to have given the receiver another lease on life. Reflecting on it later, you might think that a
receiver that old should be replaced
by a newer “better” unit.
In fact, it was already superseded
when I bought it new (at a good price)
in 1998 as it only had Pro Logic decoding, not Dolby Digital or DTS.
April 2018 43
However, it has an analog 6-channel
direct input to cater for then-future decoders, so I have used it continuously
with a variety of DVD players with
6-channel outputs, plus PVRs and
other boxes over the years.
Hence, the amp is future proof,
which fits my philosophy of also buying the dumbest TV and using it with
an external set-top box (with built-in
media server/PVR/Fetch box/etc).
It’s much cheaper to replace a box
when technology advances than replace the amplifier or large screen.
The introduction of H.264 compression is one example where this philosophy pays off.
Also, I reflected on the good electronic design that utilised 1000+ electronic components that still work
perfectly 20 years after manufacture, 25+ years after it was designed.
Would today’s replacement actually
be “better”?
Researching possible new replacement units, a popular brand has a
7-channel, 115W/channel (single
channel driven rating), and weighs
just over 8kg, retailing at about $1000.
The old Marantz weighs 14.4kg,
most of it being the power transformer. Rated at 110W/channel (two channels driven), its multi-channel performance would easily eclipse the new
unit due to the much beefier power
supply.
So I am glad to have given the old
Marantz a new lease on life. I also still
have the original RC2000 remote control – the “Remote of the Gods” – but
that is a story for another time.
Mitsubishi air conditioner repair
J. N., of Mt Maunganui, New Zealand, recently faced a common problem with his home air conditioner;
spare parts were becoming so expensive and difficult to get that it looked
like it might be cheaper to replace the
whole thing than repair one small
fault. Luckily, he managed to get it
going again anyway...
As a semi-retired electrical/electronics technician, I like to do any
servicing or repairs on our home appliances myself. The one time that I
decided not to, it ended up with me
finishing the task anyway!
About a year ago, we had an extra
Mitsubishi heat pump installed in our
house, adding to our existing old but
faithful Mitsubishi MCFH-A18WV. I
usually service the old unit myself but
we decided to have both units serviced
by the installer of the new unit before
winter set in.
They arrived and proceeded to service both units and found that the old
MCFH-A18WV would turn off OK but
the internal fan kept running.
According to the service engineer,
the problem was in the main Electronic
Control (EC) PCB and it would have to
be replaced. I requested that they give
me quote for the supply and installation of this unit.
His estimate was around $300-500
for the part plus labour, which made
me flinch! I asked him to please check
this out with a firm quotation.
A couple of days later, the company
came back with very pleasant news indeed. It appeared that because our old
unit was so outdated that there was
only one PCB in stock in the whole of
New Zealand and the agents were prepared to let us have it for only $32.90
including GST! Well, of course, we
agreed.
Several days later, our service engineer turned up and duly replaced the
Electronic Control PCB, only to find
that now the internal fan motor did
not work at all!
After a lot of testing, he now announced that the fan motor had burnt
out one of its windings and also that
the main EC PCB was probably corrupted and would have to be replaced
again!
By this time, I was beginning to
think that we should bite the bullet and
replace the whole unit. It was agreed
to get a further quote from Australia
for parts alone, ie, the fan motor and
a new EC PCB.
In the meantime, I decided that it
would not do any harm for me to investigate myself. I was able to download
the circuit diagrams and went about
conducting my own tests.
All seemed well until I came to
check the fan motor stator windings
which involved one main winding
and four separate coils, providing different fan speeds.
Sure enough, the main stator winding showed an open circuit on my
ohmmeter. This did not make sense
until I re-checked a separate circuit
diagram which showed in very small
detail that this winding was protected
by a fuse.
Where was the fuse, as none was in
sight? The penny dropped; it was embedded in the windings and was obviously a thermal fuse.
I simply bypassed this fuse by temporarily altering the wiring and the retested the winding to find that it read
the required 79-97W. At switch-on, the
unit operated as it should, so the new
EC PCB was not faulty.
True to their word, I received a
phone call from the servicing company to inform me that a new fan motor
and EC PCB would cost over $1000
plus labour and GST.
I am not sure what they thought
when I informed them that the unit
was working fine and we would not
need the new parts.
Since then, I have removed the fan
motor and installed a new thermal fuse
as best as I can, to protect the motor,
and I am still going to attempt a repair
one day on the old EC PCB which had
been previously removed. In the meantime, our good old heat pump is still
SC
chugging along.
Are Your S ILICON C HIP Issues
Getting Dog-Eared?
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Keep your magazine copies safe, secure & always available
with these handy binders
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44
Silicon Chip
Celebrating 30 Years
siliconchip.com.au
Connected
Home.
CONNECTING YOUR TECH ANYTIME, ANYWHERE
Learn
About...
GOOGLE ASSISTANT
4
$ 95
179
$
BJ-5000
SMART
MINI SPEAKER
2018
WITH GOOGLE ASSISTANT
Engineering &
Scientific Catalogue
Out Now!
FREE CATALOGUE* FOR NERD PERKS MEMBERS
WITH PURCHASES OF $30 OR MORE.
*Applies to new and existing members for purchases
made in-store or online. Valid 24 March - 23 April 2018.
279
720P WIRELESS RECEIVER AND
CAMERA KIT QC-8663
Wireless connection to any existing 720p,
1080p or 3MP AHD DVR. IP66 rated.
• 720p AHD camera resolution
• Up to 100m wireless range
• IR night vision
Control your lights from anywhere
using the free app. Simply connect
the bulb directly to your Wi-Fi
at home.
• Pair with Google Assistant
for voice control*
• Colour changing hue
$
TRUE DETECT
THERMAL SENSING
10M NIGHT VISION
RECHARGEABLE BATTERY
RECORD TO CLOUD STORAGE
AUDIO MONITORING
• Built-in rechargeable battery
• Wi-Fi & Bluetooth®
• IPX6 splashproof
SMART WI-FI LED BULB YN-8448
FROM
$
269
1080P BATTERY
POWERED WI-FI CAMERA
SINGLE
TWIN
TRIPLE
QUAD
QV-9060
QV-9062
QV-9066
QV-9068
$269
$499
$699
$899
129
$
8 ZONE WIRELESS ALARM KIT LA-5284
Pre-programmed for easy installation.
Remote control has Panic feature.
• 120dB siren
• 8 pre-set zones
SMART WI-FI PLUG YN-8446
Easily manage your household
electronic devices anytime,
anywhere! Turn on/off.
Just connect to your Wi-Fi
network and control using
the free App.
$
* Compatible with Android, iOS,
Amazon Alexa and Google Assistant
Place this wire-free
camera around the house
or office to watch live or
recorded video remotely.
Indoor/outdoor use.
IP65 weatherproof.
$
Hands free help from anywhere in your
home with this portable, great sounding
smart speaker.
BLACK XC-6000 $179
WHITE XC-6001 $179
Google Assistant is curren
tly
the most effective voice con
trol
system available in Austra
lia
and can be used with a
smartphone or smart spe
aker
such as the Tichome min
i or
Google Home. Voice con
trol
allows the user to be han
ds
free and call up free informa
tion
such as the weather, get
answers from Google etc
. and
operate/control the range
of the
new smart home technolog
y
whilst doing other tasks.
99 95
$
59 95
399
AC1300
MESH WHOLE-HOME
WI-FI SYSTEM YN-8444
Creates a unified Wi-Fi network for
seamless connection around your home.
It delivers fast, uninterrupted Wi-Fi to every room
by harnessing the power of three separate units.
139
199
$
$
AV1000 GIGABIT
POWERLINE KIT YN-8442
AC1750 WIRELESS DUAL BAND
GIGABIT ROUTER YN-8438
Extend powerline network to any room.
High-speed data transfer rate of up to
1000Mbps.
• Dual band 2.4GHz (300Mbps)
+ 5GHz (433Mbps)
Three times faster than wireless N speeds
delivering a combined wireless data transfer
rate of up to 1.75Gbps. Superior choice for
seamless HD streaming, online gaming and
other bandwidth-intensive tasks.
Buy Online, Click & Collect In Store.
Catalogue Sale 24 March - 23 April, 2018
To order: phone 1800 022 888 or visit www.jaycar.com.au
Connect Arduino® To Your Home
ESP32 Main Board
WITH WI-FI &
BLUETOOTH® XC-3800
Powerful dual core 32 bit
microcontroller equipped
with Wi-Fi and Bluetooth
connectivity. 512kB of
RAM, 4MB of memory.
Digital I/O, I2C, UART,
SPI & much more. Easy
to program, compatible
with Arduino IDE.
• 3.3V operating and
IO voltage
$
3995
BASIC BUNDLE
INCLUDES XC-4392 + XC-4394
LORA SHIELD XC-4392 $69.95
XC-4392
XC-4420
LORA IP GATEWAY XC-4394 $149
24 95
• LoRa and Wi-Fi connectivity
• Cloud-based remote management
• Detachable high-gain antenna
PROTOTYPING SHIELD
FOR WI-FI MINI XC-3850
Suit Wi-Fi Mini main board
(XC-3802) above. Build custom
circuits & interface.
SAVE $30.95
LoRa™ is a powerful new technology enabling
secure wireless data communications over long
distances without the need of a mobile GSM
network. Suitable for use in many outdoor or
indoor applications such as building automation,
weather monitoring, irrigation systems control,
smart metering, smart cities, and much more.
LEARN MUCH MORE AT www.lora-alliance.org
• Compatible with 3.3V
or 5V I/O Arduino Board.
• LoRa™ frequency Band: 915MHz
• Low power consumption
• Includes external Antenna
(via I-Pex connector)
WI-FI MINI ESP8266
MAIN BOARD XC-3802
Perfect compact solution to
your IoT sensor project. 80MHz
microcontroller with Wi-Fi on board.
$
4MB of memory, 11 digital IO pins.
• 3.3V operating and IO voltage
$188
Long Range Data
Communications:
4
$ 95
LONG DISTANCE REMOTE RELAY PROJECT:
SAVE $30.90
ULTIMATE BUNDLE
INCLUDES XC-4392 + XC-4394 + XC-4420
www.jaycar.com.au/lora-remote
7495
$238
XC-4394
Note: Radio transmitting devices must be used in accordance
with Australian Communications & Media Authority guidelines
www.acma.gov.au
$
$
Raspberry Pi 3B
SINGLE BOARD COMPUTER XC-9000
Quad-Core 1.2GHz CPU. 1GB RAM. Wi-Fi and Bluetooth®.
It can run Raspbian or Ubuntu (varieties of Linux) or even
Windows 10 IoT core. Use it as a media player or even
use the GPIO ports to connect your Arduino projects.
• Wi-Fi and Bluetooth®
• HDMI
• 4 USB ports
5
$
59 95
XC-4444
Handy addition to any Arduino® project. Wide
operating range and delay times changeable.
A must for any security application.
• 5-20VDC operating voltage
46
Raspberry
Pi not included.
5MP CAMERA XC-9020
Compact, portable display plugs straight into
the top of Raspberry Pi.
• 320 x 240 pixel
• Resistive touch
Connects directly to the camera connector on the
Raspberry Pi. Supports video recording for 1080p <at> 30fps,
720p <at> 60fps and 640x480p <at> 60/90fps.
• Based on the 5MP Omnivision 5647 camera module
• Up to 2592x1944 pixel images
24 95
14 95
Comes preloaded with the NOOBS software
for easy install of the Raspbian operating
system. Includes adaptor.
2.4GHZ WIRELESS TRANSCEIVER
MODULE XC-4508
15 95
$
16GB SD CARD WITH NOOBS
FOR RASPBERRY PI 3 XC-9030
$ 95
PIR MOTION DETECTOR MODULE
24 95
2.8" TOUCHSCREEN LCD XC-9022
9
$ 95
$
$
OFFICIAL RASPBERRY PI 3B CASE
PROTOTYPING HAT
XC-9006
Designed by the Raspberry Pi Foundation.
Snap-together case with numerous
removable panels. Stylish red and white
design. Four rubber feet included.
XC-9040
Includes screw terminals
and solder points for the
GPIO pins.
• 85(W) x 56(L)mm
19 95
19 95
$
$
RFID READ AND WRITE KIT XC-4506
Allows you to both read and write MiFareType RFID cards. Include one credit-card
Based on the NRF24L01 transceiver IC, this
module allows communication on the license style tag and one key-fob style tag.
free ISM band. Supports on-air data rates of • 3.3VDC operating voltage
up to 2Mbps.
• Communications Protocol: SPI
• 3.3V operating voltage
• Includes 2 tags (1 card, 1 fob)
• 1mW output power
Follow us at facebook.com/jaycarelectronics
RF TRANSCEIVER MODULE XC-4522
Adds a versatile 433MHz radio to your
Arduino project allowing two-way wireless
communication between Arduinos. Includes
antenna.
• 1.9-3.6VDC operating voltage
• Controlled via SPI
Catalogue Sale 24 March - 23 April, 2018
Arduino® Project Of The Month
STEP-BY-STEP INSTRUCTIONS AT:
jaycar.com.au/intruder-alert
Intruder Alert
WARNING DO NOT ENTER! You warned everyone not to - while
you are out, but how do you know if the instructions will be
followed? What if you could receive an email when someone
enters your room with the exact time they entered! This Intruder
Alert, does just that. The ESP8266 connects to your Wi-Fi network,
it keeps precise track of date and time (synchronised over the
Internet), the PIR motion sensor will detect if someone enters your
monitored zone, and it will send you email notifications. Easy to
build. No special wiring required.
VALUED AT
Works with any 5V micro USB power (not included).
$45.58
WHAT YOU NEED:
WI-FI MINI BOARD
PIR MODULE SENSOR
PROTO SHIELD
1W RESISTOR PK2
0.5W RESISTOR PK8
RED 5MCD LED
GREEN 15MCD LED
SPST MICRO SWITCH
HOOKUP WIRE
40 PIN FEMALE HEADER STRIP
XC-3802
XC-4444
XC-3850
RR-2766
RR-0596
ZD-0230
ZD-0232
SP-0601
WH-3025
HM-3230
$24.95
$5.95
$4.95
48¢
55¢
50¢
50¢
95¢
$4.95
$1.80
NERD PERKS CLUB OFFER
BUY ALL FOR
$
2995
SAVE 30%
SEE OTHER PROJECTS AT
www.jaycar.com.au/arduino
Maker Essentials:
6
$ 95
ADHESIVE COPPER TAPE
NM-2870
Perfect for circuit board repair.
• Solderable
• 5mm x 10m
1150
$
ELECTRONIC CIRCUIT
BOARD CLEANER NA-1008
Dissolves flux residues &
grime leaving the track work
and board clean. Non CFC
ozone safe propellant.
• 175g
1795
$
ANTI STATIC
WRIST STRAP TH-1781
• Adjustable hook and loop
wrist strap
• Extra long coiled lead of
3m/10ft extended
• Elastic
FROM
6
$ 95
JUMPER LEAD KITS WC-6010
Ideal for connecting devices for testing.
10 leads supplied.
STANDARD WC-6010 $6.95
HEAVY DUTY WC-6020 $11.95
Connect It:
FROM
1/m
$ 60
CCTV COMBO CABLE WB-2017
Combines RG59 coax and 16G
power cable. Sold by the meter or
by the roll.
3
$ 25
BNC CONNECTORS
RG-59 CRIMP MALE PLUG
PP-0688 $3.25
RG-59 TWIST-ON MALE PLUG
PP-0678 $3.95
BNC FEMALE WITH SPRING TERMINAL PA-3716 $4.95
14 95
$
BREADBOARD WITH 830 TIE POINTS
PB-8815
Ideal for electronic prototyping and Arduino®
projects. Labelled rows and columns.
Adhesive back for mounting.
• 200 Distribution holes
• 165(L) x 54(W) x 9(H)mm
$
29 95
LED PACK 100-PIECES ZD-1694
Contains 3mm and 5mm LEDs of
mixed colours. Even includes 10
x 5mm mounting hardware FREE!
See website for more details.
• Red, green, yellow, orange LEDs
To order: phone 1800 022 888 or visit www.jaycar.com.au
4 ea
$ 95
2.1MM
DC CONNECTORS
3.0A rated. Comes with screw terminals.
PLUG
PA-3711 $4.95
SOCKET PA-3713 $4.95
14 95
$
12 95
$
COAX SEAL TAPE NM-2828
Handy sealing system that fuses together
to form a removable, waterproof seal
once applied.
• 1.5m long
15 95
$
POCKET WIRE STRIPPER TH-1817
FILE SAW TH-2127
Strips anything from 2G to RG6 coax.
Easy to use. Small enough to take
anywhere on the job.
• 120mm long
Trim holes to any radius. Also
great for cutting odd shapes
in PVC pipes, leather etc.
• 175mm long blade
See terms & conditions on page 8.
47
Complete Your Security System
720P WI-FI PIR CAMERA QC-3860
149
$
Housed within is a pinhole • Up to 50m Wi-Fi range
camera which records
• Alarm notification via
video in 720p HD to a
Smartphone App
microSD card (available
• 103(L) x 60(W) x 29(D)mm
separately). Plug & Play
(P2P) Technology, easy
network setup.
TECH TALK:
PIR (Passive Infrared) Sensors
Detect motion of objects by sensing the change in energy emitted by
objects in its range, up to 10m. PIR sensors are small, inexpensive,
low-power, easy to use and have many applications in security,
energy saving, and robotics.
$
79
95
$
1080P TVI PIR
BULLET CAMERA QV-9007
99
$
SENSOR SPOTLIGHT SL-3238
Automatically turns on when the built-in
PIR detects movement at night. Solar
rechargeable. Adjustable spotlight head.
• 250 lumen
• Up to 5m detection distance
• 210(L) x 210(W) x 140(D)mm
$
$
44 95
95
ALARM & NBN
SYSTEM BACKUP BATTERY SB-2486
Long life and maintenance free. Ideal for
standby and emergency applications to
keep your alarm systems on the go.
• 12V 7.2 amp hour
79 95
19 95
$
7W SECURITY LIGHT SL-2799
Outputs a massive 1000 lumen of white light
when the built-in PIR detects movement.
High/low light selection. Solar rechargeable.
Perfect addition to your 3MP DVR if you need
• 1000 lumen
extra cameras. IP66 rated.
• Up to 10m detection distance
• True Detect™ PIR motion sensor
• IP65 rated
• Up to 30m IR range
• 154(W) x 183(H) x 86(D)mm
• 151(L) x 70(H) x 70(W)mm
3MP TVI
BULLET CAMERA WITH IR QV-9032
Perfect addition to your 1080p DVR if you
need extra cameras. IP66 rated.
• True Detect™ PIR motion sensor
• Up to 30m IR range
• 146(L) x 79(H) x 65(W)mm
34 95
CCD CAMERA
POWER SUPPLY MP-3011
500mA regulated switchmode plugpack.
Terminates to a 2.1mm DC plug, centre
positive, 12VDC.
19 95
$
WAS $209
WAS $119
SAVE $30
SAVE $20
179
$
$
CCTV VIDEO
& POWER CABLE WQ-7279
99
7" LCD VIDEO DOORPHONE WITH IR CAMERA
SOLAR POWERED IR WIRELESS ALERT KIT
QC-3696
Comes with 7" slimline
monitor and IP55 rated
infrared camera with rain
shield to protect from harsh
environment. 12VDC.
LA-5176
Reliable solution for monitoring
traffic in and out of driveways to
shops, large commercial and rural
properties.
• Brightness and colour
adjustments
• Ring tone selection
• Doorbell volume control
• Infrared for night time use
19
$
14
$
95
POE PASSIVE KIT YN-8410
Allows you to power wireless access points
via a Cat5 cable without the need to have a
separate power source.
• Includes input and output leads
• 2.1mm DC plug/socket
95
Combined power and video.
• BNC terminated
• Male DC plug to female DC socket
• 18m long
• Transmit up 100m range
• Up to 6m IR
detection range
$
$
FROM
29 95
12VDC POE
SPLITTER ADAPTOR YN-8414
8-PORT
ETHERNET SWITCHES
This device splits the PoE into a regular
ethernet and 12VDC plug. Allows you to
power IP cameras, and other devices which
may not support PoE natively.
• 10/100Mbps
• Up to 100m range
• 88(L) x 30(W) x 26(H)mm
Easily create or expand your wired network.
Plug and Play.
• Fanless quiet operation
• 140(W) x 76(D) x 27(H)mm
10/100MBPS
YN-8380 $29.95
10/100/1000MBPS YN-8382 $64.95
119
59
119
95
$
GIGABIT POE INJECTOR YN-8040
Adds power inline to a single network cable
up to 100m without the need of mains power.
Supports up to gigabit network for ultra-fast
connectivity.
• 10/100/1000Mbps
• 118(L) x 59(W) x 37(H)mm
48
$
POWERLINE ETHERNET EXTENDER
YN-8355
Connect up to 4 Power Over Ethernet (PoE) IP Extend your ethernet over mains power
cameras, routers, and networking equipment. connections. Allow HD streaming, fast file
transfers, and more. Plugs directly into mains
• 10/100Mbps
power outlet.
• Up to 100m range
• Fast 500Mbps speed
• 118(W) x 85(D) x 27(H)mm
• 58(W) x 73(H) x 90(D)mm
5 PORT POE SWITCH YN-8074
Follow us at facebook.com/jaycarelectronics
AC/DC - DC CONVERTER MP-3350
Solve your power cabling problem
quickly and easily by sending 24VAC
down the long run, then converting
it to 12VDC. Connection is by screw
terminals.
• 1A max
14 95
$
$
39 95
BNC TO CAT5E/6 UTP AHD VIDEO
BALUN KIT QC-3667
Extend the transmission distance of your
CCTV setup without the need for a video
amplifier.
• Up to 400m transmission range
• Support: AHD, TVI, CVI, Analogue
• 38(L) x 19(H) x 12(W)mm
Catalogue Sale 24 March - 23 April, 2018
TECH TALK:
Digital Video Recorder (DVR)
Vs. Network Video Recorder (NVR)
Video surveillance systems have many applications in the home, office,
commercial and public venues. Depending on the choice of camera technology
you will require either a Digital Video Recorder (DVR) for connecting to analogue
cameras, or a Network Video Recorder (NVR) for connecting digital IP cameras.
A DVR and NVR essentially provide a central connection, control, storage and
streaming of your surveillance video camera network. Most DVR’s and all NVR
systems provide secured remote access, allowing you to conveniently view your
camera footage over the Internet.
$
289
500GB
HDD
CLOUD
STORAGE
720P
AHD
$
499
1TB
HDD
Analogue and digital IP cameras offer comparable video quality, IP Cameras
offer slightly higher image resolution, and greater flexibility as they can be
connected to the NVR unit via wireless, Wi-Fi or only require standard network
Ethernet cable connection. Analogue cameras, on the other hand, require
special coaxial and power cable connection from each camera to the DVR unit.
Planning your surveillance network is very important whether you use a DVR or
NVR, you need to ensure there is enough storage capacity to record your video
footage over the required surveillance duration say 24 hours, 48 hours, etc.,
In the case of an NVR you also need to ensure there is enough data network
bandwidth to carry the video footage data stream from each camera to the NVR
unit, without affecting the rest of your data network.
CLOUD
STORAGE
1080P
AHD
4 CHANNEL 720P AHD QV-3161
8 CHANNEL 1080P AHD QV-3157
• Up to 6TB 3.5” SATA capacity
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 18 days recording time
• 300(L) x 227(W) x 53(D)mm
• Up to 6TB 3.5” SATA capacity
• Touch button
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 17 days recording time
• 300(L) x 227(W) x 53(D)mm
$
399
500GB
HDD
CLOUD
STORAGE
720P
4 CHANNEL 720P DVR KIT
WITH 4 X 720P CAMERAS QV-3135
$
FROM
599
1TB
HDD
CLOUD
STORAGE
1080P
1080P DVR KITS WITH 4 X 1080P CAMERAS
• Up to 6TB 3.5” SATA capacity
• IP66 rated camera
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 18days recording time
• 300(L) x 227(W) x 53(D)mm
READ THE FULL ARTICLE:
jaycar.com.au/dvr-nvr
• Up to 6TB 3.5” SATA capacity
• IP66 rated camera
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 40 days recording time
• 300(L) x 227(W) x 53(D)mm
4 CHANNEL QV-3164 $599
8 CHANNEL QV-3166 $699
$
749
2TB
HDD
CLOUD
STORAGE
3MP
AHD
16 CHANNEL 3MP AHD QV-3159
• Up to 6TB 3.5” SATA capacity
• Touch button
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 8 days recording time
• 300(L) x 227(W) x 53(D)mm
$
899
2TB
HDD
24/7
SWANN
SUPPORT
3MP
8 CHANNEL 3MP DVR KIT
WITH 6 X 3MP PIR CAMERAS QV-9030
• Up to 6TB 3.5” SATA capacity
• True Detect™ PIR Motion Sensing Technology
• IP66 rated camera
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 365 days recording time
• Lifetime 24/7 Swann Support • 275(W) x 220(D) x 53(H)mm
SAVE
$200
$
NOW
399
SAVE $200
1TB
HDD
CLOUD
STORAGE
720P
$
799
1TB
HDD
CLOUD
STORAGE
1080P
1199
$
2TB
HDD
24/7
SWANN
SUPPORT
4MP
4 CHANNEL NVR KIT
WITH 720P POE IP CAMERAS QV-3132 WAS $599
4 CHANNEL 1080P WI-FI NVR KIT
WITH 4 X 1080P CAMERAS QV-3162
8 CHANNEL NVR KIT
WITH 4 X 4MP CAMERAS QV-9012
• Up to 4TB 3.5” SATA capacity
• IP66 rated camera
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 90 days recording time
• 300(L) x 227(W) x 53(D)mm
• Up to 6TB 3.5” SATA capacity
• Up to 50m wireless range
• IP66 rated camera
• P2P Technology
• Motion detection, email & push notification alerts
• Up to 10 days recording time
• 300(L) x 227(W) x 53(D)mm
• 2TB SATA, supports up to 3TB internal
& 1 x 3TB eSATA capacity
• Up to 30m range
• IP66 rated camera
• P2P Technology
• Motion detection, email & push notification alerts
• 160+days recording time
• Lifetime 24/7 Swann Support • 255(W) x 230(D) x 51(H)mm
To order: phone 1800 022 888 or visit www.jaycar.com.au
See terms & conditions on page 8.
49
Workbench Essentials:
There has been an obvious resurgence in people getting back to the workbench and
reviving skills involving manual dexterity. As you will see across the following pages,
Jaycar has all the DIY tools you'll need to equip your workbench so you can create
projects from the power of your brain and your hands.
1
2
NOW
$
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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.
Temperature and humidity display using a PIC16F88
Back in the February 2017 issue of
Silicon Chip, Jim Rowe wrote an excellent article on the AM2302/DHT22
temperature and relative humidity
sensor module (www.siliconchip.com.
au/Article/10529).
Not having a Maximite or Arduino
but having lots of PIC16F88 microcontrollers, I thought I would design
a circuit using one of those to display
the temperature and relative humidity on an LCD.
The main difficulty in doing this is
the fact that the AM2302/DHT22 does
not use a standard communications
protocol but rather a custom one so
I had to write software for the PIC to
receive data from the sensor.
The pin 2 output of the AM2302 is
connected to RB0 on IC1. Initially, this
port is made an output and the micro
then takes this pin low for 1ms.
The port is then made an input and
the AM2302 sends out an acknowledgement (positive) pulse of 80µs. IC1
checks the width of this pulse and if
siliconchip.com.au
it is less than 60µs, it starts the whole
process again.
If it is more than 60µs, the pulse
width is stored (as a reference) and it
then waits for and stores the duration
of the next 40 pulses in memory. These
encode the humidity, temperature and
checksum data.
It then goes through these stored
pulse widths to determine if each one
represents a logic 1 or a 0. A logic 1 is
assigned to any pulse of 60-90µs and
a logic 0 for any of 20-40µs.
The relative humidity is calculated
from the values of the first 16 bits, the
temperature from the next 16 bits and
the checksum from the last 8 bits. If the
checksum value received matches the
checksum of the rest of the data then
the relative humidity and temperature
are displayed on the LCD.
In the unlikely event that interference causes the parity to be incorrect,
an asterisk (“*”) is displayed before
the humidity and temperature to tell
you that the reading may be incorrect.
Celebrating 30 Years
The rest of the circuit is simple.
The PIC drives the alphanumeric LCD
using the 4-bit parallel bus. It also has
a 20MHz crystal connected between
pins 15 & 16, with 15pF load capacitors, so that the chip can accurately
measure the width of the pulses from
the DHT22.
The whole circuit runs from a 9V
unregulated supply which could come
from a battery or plugpack. The 9V
supply is regulated to 5V to suit all the
other components by a TO-92 package
LP2950-5 linear regulator. 10kW potentiometer VR1 enables you to adjust the
contrast of the LCD screen.
The software was written using
PICBASIC PRO. The commented
source code "Temp hum 3.bas" and
HEX file "Temp hum 3.hex" can be
downloaded from the Silicon Chip
website, free for subscribers. The HEX
file can then be flashed to the PIC using a PICkit 3 or similar.
Les Kerr,
Ashby, NSW. ($60)
April 2018 53
Electric Guitar/Violin preamp runs off USB supply
This high-input-impedance preamp
has been designed to run at 5V to provide the convenience of operating from
a USB supply. That means you can
power it from the USB port of a computer, a USB charger or power bank.
It only draws a few milliamps.
You need to have a high input impedance, usually at least 1MW, for a
piezo-electric instrument pickup or
else the low end frequency response
can suffer.
One of the challenges of designing
such a preamp to run off 5V is that the
instrument can produce a fairly high
output voltage which would exceed
the 5V rails. So this preamp includes
a selectable input divider to reduce the
instrument voltage to a suitable range
for the preamp. The signal level can
then be boosted again before being fed
to the output.
54
Silicon Chip
The circuit is designed around an
MCP6024 quad rail-to-rail op amp.
This op amp runs from a 2.7-5V supply, it has a gain bandwidth product
of 10MHz, a noise figure of 8.7nV/√Hz,
total harmonic distortion below
0.001% and it is unity gain stable. It’s
also quite reasonably priced.
It has CMOS inputs, so can be used
in circuits with a high input impedance without a high DC bias voltage.
There are various other similar op
amps which are suitable but they are
generally not as good. These include
the MCP604, MCP6284, MCP6074,
LMV324, LMV774 and LMV824 but all
of these have lower gain bandwidths
and higher noise figures.
Turning now to the circuit, the signal from the instrument is fed in via
CON1 and this is AC-coupled to a
1kW series current-limiting resistor,
Celebrating 30 Years
followed by a resistive divider comprising four resistors. These resistors
total just under 2MW, defining the input impedance.
Rotary switch S1 allows you to feed
the unattenuated signal to input pin
3 of IC1a, or one of the taps on the resistive divider network which give attenuation factors of 2, 4 or 8. Diodes
D1 and D2 ensure the signal fed to
IC1a does not go very far below 0V or
above 5V. IC1a is configured as a unity-gain buffer.
Note that the bottom end of the divider network does not go to ground,
but instead to a half supply rail (nominally 2.5V). This is so that the signal
applied to IC1a is kept between its
supply rails, even for negative signal
excursions. Basically, the whole signal
is shifted up by 2.5V.
The bias is generated by the two
siliconchip.com.au
2.2kW resistors across the 5V rail,
shown at upper left, with a 220µF filter
capacitor to prevent supply ripple and
noise from getting into the signal path.
Diode D3 discharges this capacitor quickly when power is removed
so that it does not discharge into one
of the op amp inputs via the op amp’s
internal clamp diode.
The buffered signal from IC1a is fed
to CON3 via a 100W series resistor and
220µF capacitor. The resistor isolates
any capacitance at the output from op
amp IC1a, so that it won’t oscillate,
while the capacitor blocks the 2.5V
DC bias voltage.
The output end of this capacitor is
biased to 0V DC (ground) potential
via a 33kW resistor. A 100nF capacitor across the 220µF capacitor keeps
the output impedance low at higher
frequencies.
The buffered signal is also fed to the
non-inverting input (pin 5) of IC1b via
a 1kW resistor.
This resistor is inserted to keep the
input impedance seen by the op amp’s
two inputs similar, avoiding excessive
thermal drift and improving common
mode rejection. IC1b is configured as
a gain stage with selectable resistors
in the feedback network so that S2
can select one of five different gain
settings.
With S5 in the upper position, the
gain can be varied between two times
and 52 times using potentiometer VR1.
The other four positions give fixed
gains of two times, 4.3 times, 11 times
or 21 times.
This allows you to use the preamp
with different instruments and quickly
switch to the required gain setting for
each one. The output of IC1b is fed to
CON4 via the same coupling arrangement as CON3, described above.
S3 allows you to select the output
of either IC1a (buffered only) or IC1b
(with gain) to feed to the mono headphone driver, which is built around
IC1c and IC1d.
These are configured as unity-gain
buffers and connected in parallel, with
22W resistors from the outputs to prevent them fighting each other due to
slightly different DC offsets.
This arrangement increases the
output current capability and allows
the op amps to drive a lower load impedance.
The common output is coupled
to the headphone(s) via another
220µF/100nF capacitor pair and also
biased to ground by a 33kW resistor.
With 30W headphones (only one side
driven), you can expect a frequency response down to about 1 ÷ (2π × 30W ×
220µF) = 24Hz (the -3dB point).
The power supply is simple; around
1mA is fed through power indicator
LED1 and a 2.2µF capacitor stabilises the supply voltage (note: the USB
specification allows limited capacitance across the USB socket, to prevent high current flow when plugging
the device in).
An LC low-pass filter comprising
100µH inductor and 220µF capacitor
filters out the worst of the high-frequency noise which may be present on
the output of USB chargers. 100nF and
1nF parallel bypass capacitors are provided for quad op amp IC1; the lowervalue capacitor will typically be more
effective at higher frequencies.
Petre Petrov,
Sofia, Bulgaria. ($65)
Recycling old hard disk spindle motors
Useful motors can be salvaged from
defunct hard drives and they can be
used for many projects that require
a low-power motor, especially one
which can spin at a high rate.
Typical hard disk motors are designed to spin at 5400, 5900 or 7200
RPM although some run as fast as
15,000 RPM.
The only difficulty in re-using them
is the electronics required to drive
them. These are three-phase motors
with four wires but they can be driven
as a standard Brushless Direct Current
(BLDC) motor by ignoring the centre
connection.
A simple way to drive these motors
is with the MTD6501G single chip
BLDC motor driver from Microchip.
The chip is only available in a surface mount (SOIC-8) package but this
can easily be soldered to an SOIC-8 to
DIL-8 adaptor board (eg, Silicon Chip
Online Shop Cat SC3195 or SC3196)
so it can be used on a breadboard or
prototyping board.
The SC3196 adaptor has a thermal
pad which can be soldered to the unsiliconchip.com.au
derside of the IC for better heat dissipation.
You can use hot air reflow with solder paste to make the solder joint under the IC but if you don’t have the
equipment, you can simply smear
some flux paste on both sides of the
PCB before soldering the IC pins, then
flow solder through the central via
from the underside of the board.
The circuit diagram shows the required connections. Speed control can
Celebrating 30 Years
be provided by a pulse width modulated (PWM) signal from virtually any
microcontroller including Arduino,
Micromite, Raspberry Pi etc.
Set the duty cycle to 50% and vary
the frequency to control the motor
speed. Connecting the PWM input
directly to Vcc will provide maximum speed.
For most motors, a VCC of 3.3V or
5V is suitable, although this probably
won’t allow the motor to run at full
April 2018 55
Simple Valve Radio Battery Eliminator
This circuit is similar in concept
to the Mains Power Supply for Battery Valve Radio Sets (August 2017;
siliconchip.com.au/Article/10751).
This circuit is considerably simpler, easier to build, cheaper and safer
(since its mains transformer is a plugpack), however, it doesn’t provide
quite as many supply options.
I decided to design this because I recently acquired a battery valve radio
from the 1950s. It’s a Philips model
with four valves in a standard superhet
configuration. It runs from batteries,
without a mains supply option. Like
many battery valve radios, it needs
1.5V DC for the filaments and 90V for
the HT supply.
Since the old-style A/B batteries are
no longer available, I could have used
a D cell for the filaments and ten 9V
batteries in series to achieve 90V. But
that would not be very satisfactory
from my point of view. And anyway,
I already had all the parts to build this
supply in my collection.
As shown in the circuit diagram, I
used an AC plugpack with a 9V, 1A
output. This is fed to a 7VA PCB-mount
transformer with a 230V primary and
two 12V secondaries. By feeding the
9VAC into the two 12V windings in
series, this gives 92VAC on the 230V
winding with no load.
This is higher than the turns ratio
would suggest and is due to the fact
that with no load, the 9VAC output
of the plugpack is actually about
11.8VAC.
Bridge rectifier BR2 followed by a
33µF, 150V electrolytic capacitor converts this 92VAC to 123V DC, again,
with no load. 33µF is quite adequate
for filtering.
I used a 350V capacitor since I had
it in my parts bin. A 150kW resistor
Removing the spindle motor from a hard drive typically requires the
entire drive to be dismantled. Depending on how the motor is attached
to the frame/platter you might also need to use a nail punch to dislodge it.
56
Silicon Chip
Celebrating 30 Years
across the 33µF capacitor discharges
it quickly at switch-off and dissipates
under 100mW.
To obtain the 1.5V DC for the filament supply, I wired bridge rectifier
BR1 across just one 12V winding, with
a 2200µF capacitor for filtering.
Hence, I am using the input side of
T2 as an auto-transformer to lower the
AC voltage. This gives about 6.2V DC
to feed to the LM317 adjustable regulator, REG1.
The two resistors between the output and adjust pins of REG1 and
ground actually give me 1.56V DC.
I designed it this way because I discovered that the ON/OFF switch on
my radio has a rather high resistance
and no matter how much I cleaned it,
there was about a 0.1V drop across it.
But any set that’s designed for 1.5V
should run happily at 1.56V.
The transformer isolates the low
speed; the hard disk controller would
normally use a 12V supply and probably a different control method.
There are numerous styles of hard
disk motor but most are similar to the
one shown in the photograph directly
to the left.
In order to identify the common
connection, measure the coil resistance between each connection with
an ohmmeter (eg, DMM set to ohms).
One pin will show a lower resistance reading to the other three. This
is the common connection since the
reading is across only a single coil. A
typical resistance reading is on the order of 3-4 ohms.
Dennis Smith,
Strahan, Tas. ($60)
siliconchip.com.au
voltage and high voltage outputs (ie,
they can float relative to each other)
so there should be no problems with
whatever biasing scheme is used in
the radio.
As mentioned earlier, the no-load
HT output is higher than the required
90V but once connected to my set, it
drops to about 86V with a ripple of
1.5V peak-to-peak.
Given that the plugpack output
winding has a resistance of 450W and
T2’s windings are around 570W each,
voltage regulation is not great. But in
this case, that works in my favour.
There are many variations possible
with this kind of configuration. You
can change the HT voltage somewhat
by substituting a different transformer
for T2. For example, using a 15-0-15
transformer would give you a lower
HT while a 9-0-9 would give a higher HT.
A photograph of my prototype is
shown above. Despite the fact there
is no mains wiring inside the box,
siliconchip.com.au
The circuit can be built on a breadboard due to how few components there are.
The only reason the transformer is mounted sideways is to fit into the case.
don't be complacent, 100V+ can still
be dangerous. Use heatshrink to insulate all the wiring associated with
the HT output.
You will notice that I’ve mounted
the transformer sideways. This is simply because, if mounted in the nor-
Celebrating 30 Years
mal orientation, it’s too tall to fit into
the case that I happened to have (and
which is otherwise a good fit). A couple of wire straps and the lid hold it
in position.
Charles Kosina,
Mooroolbark, Vic. ($60)
April 2018 57
How to use Internet Time with GPS clocks
The “Clayton’s”
GPS Time Source*
We’ve produced a number of GPS-based clocks over the last few years
but they can be problematic if you can’t get a GPS signal – deep inside
a building, for example. But how about this for a clever alternative:
program a cheap WiFi Module to act as a time reference, kept accuracy
via the internet! It pretends to be a GPS unit, so any GPS clock can use it!
By Tim Blythman
C
The beauty of this system is that it presents this time
lock projects that depend on a GPS source as the
reading as if it’s coming from a GPS module, so you don’t
time reference can be relied on as being highly achave to make any changes to the clock hardware or softcurate – after all, the time code in the GPS signal is
ware. You could build any of our GPS clocks and with just
derived from an atomic clock.
a small amount of extra effort, get them to run off Network
The most recent GPS-synchronised clocks we’ve pubTime Protocol (NTP) time via your existing WiFi network.
lished are the Analog Clock Driver (February 2017;
It should even work with commercial, pre-built GPS clocks.
siliconchip.com.au/Article/10527 and the High Visibility
In fact, this concept can be used with any device that
6-Digit LED GPS Clock (December 2015 & January 2016;
uses a GPS module to get a time signal.
siliconchip.com.au/Series/294).
It doesn’t need to be a clock. But keep in
And in the case of the High Visibility
mind that it may not be accurate enough
6-Digit LED GPS Clock, it requires no
to use as part of a time reference system.
manual adjustments for daylight saving
or time zones as it can determine these
How it works
adjustments based on location data from
As already noted, we’re using an
that same GPS module.
ESP8266 module which is available preUnfortunately, all GPS-based clocks
assembled, already having an onboard
are subject to one caveat: they won’t
WiFi transceiver. We program it using the
work well without having a clear
Arduino IDE. IDE stands for Integrated
“view” of the sky, so that they can pick
Development Environment, which means
up the signals from multiple GPS satthat it lets you write code for an Arduino,
ellites. While GPS signals can usually
then compile it and upload it to the board.
be picked up indoors, whether you will
And note this point; while we are usget them at a given location depends on
ing the Arduino IDE, we are not using an
the construction of the building – and
Arduino Uno or related Arduino board!
even the weather.
The software we have developed
But many readers will already have
fetches the current time and date from
a WiFi network at home and that gives The NTP WiFi
module we chose, the
an NTP server via the internet, then it
an alternative source of time that’s al- ESP8266 WeMos D1 Mini Module
uses this timestamp in combination with
most as accurate (far more accurate than (available from Jaycar, Cat XC-3802).
its internal clock to generate a stream of
you’re ever likely to need!). So why not
GPS-compatible (NMEA encoded) data,
take advantage of it?
including time signals.
This project takes a cheap and readily available ESP8266
It is possible to estimate your location based on your
WiFi/ARM processor module and uses it to fetch accuinternet IP address, so our software does just that, transrate time readings from the internet and pass it through
lating the IP into a latitude/longitude pair using an online
to the clock.
*The time source you have when you don’t have a GPS time source!
58
Silicon Chip
Celebrating 30 Years
siliconchip.com.au
service. So if you are using this module with the High
Visibility 6-Digit LED GPS Clock, it can use these coordinates to calculate the correct time zone and daylight saving
rules, and it will display the correct local time.
While we’ve found that the estimated position can sometimes be a few dozen kilometres out, in 99.99% of cases,
this will still be in the same time zone, so the time displayed will still be correct.
But if you are using a proxy or VPN, this information
may be inaccurate, as the IP service may return coordinates
based on your proxy location. But for most home WiFi setups, this should not be a problem.
NMEA GPS data
NMEA stands for National Marine Electronics Association; NMEA 0183 is a specification for communication between marine electronics systems, including GPS receivers. Pretty much all GPS receivers produce serial data in
this format, which is why we’ve designed our unit to use
this same standard.
We’ve described the NMEA 0183 standard in detail in the
past and we will give some examples below. But for now,
you just need to understand that the data is sent over an
RS-232 (or similar) serial link, in ASCII text format, with
each distinct line being considered a “sentence”.
Each sentence is prefixed with a code which indicates
what data is contained within. So units receiving this data
can skip any sentences with codes that they don’t understand. Each sentence contains a series of values separated
by commas and terminated with a checksum, so that data
which is corrupted during transmission can be ignored.
Since the information from a GPS receiver is simply serial ASCII data, it’s easy for a microcontroller to mimic. A
GPS receiver will usually transmit around 3-10 sentences,
sent once per second. But for our clock projects, only two
are important.
These are the RMC (minimum recommended GPS) and
GSA (fix validity and active satellites) sentences. RMC contains the GMT/UTC time, date, latitude, longitude, speed,
course and magnetic variation data. GSA indicates whether
the unit has obtained a GPS fix and a partial list of the satellite Ids used to obtain that fix. See Fig.1 for an example.
This was taken from a real GPS receiver.
Without an actual GPS receiver, the latitude, longitude
and satellite status will have to be fabricated or estimated;
the only information which absolutely needs to be correct
is the time and date.
We’ve also written the software to produce a “dummy”
status sentence to show some information about the status of the WiFi connection. Since this is a sentence type
that the clocks are not programmed to interpret, they will
ignore it. But you could monitor the output of the serial
port using a PC as a debugging aid.
What is a Clayton’s GPS Time Source?
Some readers (particularly younger ones) may not understand
the reference to “Clayton’s” – arguably, one of the most famous
tag lines to come out of Australian advertising (OK, that and “NOT
HAPPY, JAN!”).
Back in the 1970s and 80s, there was a non-alcoholic drink
called “Clayton’s” which was advertised as “the drink you have
when you’re not having a drink”. They, of course, meant alcohol.
Very quickly, the phrase entered the Aussie vernacular; it meant
the (fill in blank) you had when you’re not having (or possessing,
or owning, or using etc etc etc!) a (fill in blank).
Our “Clayton’s” GPS time source is therefore the time source
you have when you don’t have access to GPS – whether that’s
because you don’t have one (!) or because it doesn’t have the
clear view of the (northern in Australia) sky and so cannot receive
the valid GPS signal.
Network Time Protocol
NTP is one of the oldest internet protocols still in use.
It’s used by pretty much every computer and smartphone,
to keep their clocks accurate.
NTP, designed to be simple and fast so that the overhead of checking and adjusting the time is minimised, is
well suited to implementation on a small device like an
ESP8266 module. It’s also designed to compensate for networks delays.
Ultimately, NTP time comes from a source which typically has a caesium atomic clock. From there, the time is
distributed to other nearby servers. Our unit will most likely be getting its data via a path that is three or more levels
(or “strata”) removed from the atomic clock.
In other words, we’re synchronising our time to servers which synchronise their time to other servers which
synchronise their time to other servers which have atomic
clocks attached. Whew!
But you can still expect the resulting time to be accurate
within about 10ms. Given that we are transmitting this data
$GPRMC,013115.000,A,3345.6276,S,15116.8171,E,0.00,157.
35,140218,,,A*76
$GPGSA,A,3,05,31,25,29,02,,,,,,,,2.22,2.02,0.92*02
Fig.1: an example of typical RMC and GSA sentences from
a real GPS receiver. The RMC sentence provides basic fix
data such as latitude, longitude, speed, heading, and most
importantly, date and time. In this case, the UTC time is
1:31:15am and the date is 14/02/2018.
siliconchip.com.au
Celebrating 30 Years
Here’s an
alternative
ESP8266 module,
the ESP-01
(available from
the Silicon Chip
Online Store,
Cat SC3982). It’s
smaller but it’s
not quite as easy
to program in
situ. We have an
article describing
this module in
detail on page 76
of this issue.
April 2018 59
Fe at ur es & sp ec ifi ca tio ns :
to a clock which will be only
results and use that as the corbe displaying to the nearest
rect time.
second, that should be accu- * Uses low-cost ESP8266 WiFi module
Keeping track of time
rate enough.
Comparable in size to a GPS module
To determine the time us- *
The NTP-based GPS Time
ly required
ing NTP, the unit sends out * Little or no assemb
Source uses its internal oscilincluding
a number of packets over * Generates standard GPS NMEA data
lator and timer to keep track
dity
vali
al
sign
the internet to NTP servers
of time in the short-term, so
time, date, position and
and uses its internal clock * Also produces 1PPS pulses (D1 version only)
it does not need to constantly
to keep track of when each
re-query the servers to detert
rne
inte
from
e
tim
NTP
tically fetches
packet is sent and when a re- * Automa
mine the time.
servers
ply is received. The response
This oscillator’s frequency
tion, for clocks with
also includes the time (ac- * Provides approximate loca
may not be exactly right and
location-based time zone support
cording to the server) when
it could vary with temperaour query was received and * Adjustable baud rate
ture and other factors but
when the response was sent.
since we synchronise it fret
* Configured via serial por
The packets are sent using the
quently using NTP, it should
ing
ugg
deb
for
my status sentences,
low-overhead User Datagram * Produces dum
never drift very far.
Protocol (UDP).
In fact, by looking at how
* Power supply: ~70mA at 3.0-5.5V
Using this information, we
it’s drifting each time we get
can determine the round-trip
a time update via NTP, we
time, ie, the time it takes for our query to get to the server
can account for and cancel out some of this drift.
plus the time it takes to get the response. Normally, the
That’s important since we use this oscillator to deterroute taken by both packets will be similar and so the demine the one-second intervals on which to send the NMEA
lay will be similar.
data and this gives the clock its seconds “tick”. If that was
By subtracting the time that the server spent processing
inconsistent or worse, glitched (eg, giving two pulses in
our request from the round trip time and dividing by two,
short order), you would probably notice.
we can get a pretty good idea of how long the response
By default, we perform an NTP update at hourly intertook to get to us. We can then add that delay time to the
vals. The oscillator in the ESP8266 micro is typically acaccurate time we receive from the server and that should
curate to within about ±0.001%. That means that, uncorbe close to the exact time when the response was received.
rected, it will drift by up to 42ms each hour. That’s hardly
Since we query a number of servers, if a majority of the
noticeable and the corrected drift is likely to be well within
times determined from the responses are within a few mil10ms. You aren’t going to notice a 10ms “jump” when the
liseconds of each other, we can be fairly sure that we have
time is updated from NTP.
a good determination of the time and we can average those
One thing we haven’t mentioned yet is that there are ac-
Fig.2: circuit diagram of the original WeMos D1 mini, which has now been cloned and is widely available. It’s based on
an ESP8266 WiFi module with onboard processor but contains extra circuitry to make it easier to program and use.
60
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Celebrating 30 Years
siliconchip.com.au
Fig.3: there are several different versions of the D1 Mini
board but they are all suitable for this project and have the
same pin-out, as shown here. The one we used (a common
clone) looks like this but there may be slight variation in
the components on the board.
Fig.4: the only part mounted on the the top side of the D1
Mini module is the ESP8266 sub-module, which contains
the IC itself plus a few passive components inside a metal
shield can. This is the side normally visible when the
module is plugged into another board.
tually two different hardware units which you can use for
this project. One is smaller and cheaper (ESP-01) but only
has eight pins. The slightly larger module (D1 Mini) has
more pins and this allows us to also provide a 1PPS (one
pulse per second) output, for clocks which require it. See
Figs.2, 3 & 4 for details of the D1 Mini.
If available, the 1PPS output is generated from the same
oscillator and is driven high briefly at the same time that
we start to transmit the NMEA data. We’ll get back to discussing the two different hardware modules later.
NTP always gives UTC or Universal Coordinated Time.
This is the modern, more accurate version of Greenwich
Mean Time, which differs from GPS time by (currently) 18
seconds due to the fact that the GPS satellites are not adjusted for leap seconds when they occur.
However, the GPS data stream does include information
about how many leap seconds have occurred, so this can
be corrected for.
Most GPS receivers are able to use this information and
so give the correct UTC time, but some receivers don’t apply the leap second change at the right time. This means
that using NTP may actually be more accurate than some
GPS receivers.
some status information. While the small PCB antenna on
this module doesn’t have a long range, it’s expected that it
will be used indoors (where GPS isn’t available) and probably not too far from a router.
ESP8266 module
The small size of the ESP8266 module means that it can
function as a direct drop-in replacement for many GPS
modules.
There are quite a few different ESP8266-based modules
available. Our preference is for the WeMos D1 Mini, which
includes an onboard USB/serial converter to simplify programming, as well as a 5V regulator, allowing it to be used
with both 5V and 3.3V power supplies.
Other modules like the slightly smaller ESP-01 can also
be used, but you will need a USB-serial converter to program it and pull-up resistors are also required to get it to
operate in the correct mode. We’ll show you how to use
either module for this project.
The features of the module that we are using are the WiFi
connectivity, serial port and also the onboard LED to report
siliconchip.com.au
Circuit diagram
The circuit diagram for the ESP8266 WeMos D1 Mini
module (available from Jaycar, Cat XC-3802) is shown in
Fig.2 and its pinout is shown in Figs.3 & 4. Since this is a
pre-built module which does pretty much everything we
need it to do, there’s no additional circuitry required. We
simply feed power into the GND and 3V3 pins and the emulated GPS serial data appears at the TX pin.
If your clock supplies 5V to the GPS module then you
can feed this into the 5V pin instead. The onboard regulator then derives the 3.3V supply which powers the module.
Regardless, the serial data output will have a 3.3V swing
but this is true of most GPS modules (even if they run off
5V) so the clock should not have any problem with this
(5V micros can normally accept 3.3V logic levels at their
digital inputs).
You can also use the smaller ESP-01 Module (available
from Altronics, Cat Z6360) but it cannot easily be programmed as-is. You will need a breadboard, some jumper
wires and a few resistors so that you can program it. You
will also need to add some components to the board before
mounting it in the clock, so that it will operate normally.
The ESP-01 also does not include a 3.3V regulator, so
the host circuit will have to supply it with 3.3V or thereabouts (3.0-3.6V is acceptable).
Programming it
Regardless of which module you’re using, you need to
install the Arduino IDE and the ESP8266 processor addon so that you can upload the code to it. If you haven’t already done this for a previous project, use the following
steps – and if you do already have this software installed,
check to make sure you have the latest version.
First, install the most recent version of the Arduino IDE
onto your PC, if you don’t already have it. This can be
Celebrating 30 Years
April 2018 61
Fig.5: this is how the ESP-01 module is connected for programming. Note the two loose wire “ends”, which
are used to put the module into programming mode.
downloaded for free from www.arduino.cc/en/Main/Software
Next, install the ESP8266 board files. This is also a free
download but it’s quite large and will take a while. To do
this, open up preferences in the Arduino IDE and under
“Arduino Board Manager URLs”, enter: http://arduino.
esp8266.com/stable/package esp8266com index.json (as
shown in Fig.6).
Hit OK, then go to Tools Boards Board Manager,
type in “esp8266” in the search box, click on the entry
which appears below and then click on the “Install” button (see Fig.7). This will result in around 160MB of compilers and associated files being downloaded and installed
on your computer.
There are two main build options, so we’ll run through
the easier option first. This is using the D1 Mini module.
Go to Tools Board menu and select the “WeMos D1 R2
& mini” entry. There are no additional libraries to install,
as the basic WiFi feature libraries are installed with the
ESP8266 processor add-on.
Using a micro-USB cable, plug the D1 Mini module into
your PC. Check the ports under Tools Ports to see that
the driver is installed and select the port. If it is not installed, the driver can be downloaded from https://wiki.
wemos.cc/downloads
Open the .ino sketch file (downloaded in a ZIP from the
SILICON CHIP website) and select Sketch Upload. If everything completes successfully, you can jump ahead to the
Setup section.
Using the ESP-01 module
The ESP-01 module is less than half the size of the D1
Mini, which means it can’t fit a lot of the nice features of
the larger board (such as the onboard USB/serial converter).
Still, it isn’t too difficult to build a rig for programming this
tiny module. You will need a separate USB/serial converter with a 3.3V supply output, as the ESP-01 will not like
5V! We have a suitable device in our SILICON CHIP Online
Shop (Cat SC3437). See Fig.5 for the connection diagram.
Connect one male/female jumper lead to each of the ESP01’s pins except for GPIO2 and run the other end to one edge
of the breadboard. We used red for VCC, black for GND, orange for TX, yellow for RX, green for RST, blue for GPIO0
and mauve for CH_PD (“Power down”). The mauve lead
for CH_PD can connect to the same row as VCC, as CH_PD
needs to be pulled up to Vxx for the module to do anything.
Connect another four male/female jumper leads to the
http://arduino.esp8266.com/stable/package_esp8266com_index.json
Fig.6: before you can install the ESP8266 Board file, you
need to tell the Arduino IDE where to find it. You do that in
the Preferences dialog, as shown here.
62
Silicon Chip
Fig.7: this shows how you install the ESP8266 “core” files
in the Arduino Board Manager. That lets you compile and
upload code to ESP8266-based boards, including the ESP-01
and WeMos D1 Mini.
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USB-serial converter and then connect these to
Our ESP-01
the ESP-01 via the breadboard as follows: red
programming rig,
lead to 3.3V, black to GND, orange (from TX
corresponding to
on the ESP-01) to RXD on the USB/serial conFig.5. It looks a bit
verter, and similarly, yellow (from RX on the
complicated but
ESP-01) to TXD on the USB/serial converter.
really there isn’t
much to it apart
The ESP-01 module needs some pull-up refrom a number of
sistors for correct operation, so connect a 10kΩ
jumper leads.
resistor from the VCC row to the RST row (between the green and red jumper leads), and
another 10kΩ resistor from the VCC row to
the GPIO0 row (between red and blue jumper
leads). See Fig.5 for details.
Finally, using male-to-male jumpers, add
flying leads to the RST and GPIO0 rows (green
and blue). These are now our reset and programming jumpers and we plug them into the
GND row to activate them. If you prefer, you
could even fit some tactile pushbuttons to the
breadboard if you are going to be using this
setup more than once.
To reset the ESP-01, touch the green lead to
GND. To enter UART upload (programming)
mode, hold the blue wire against GND, then
briefly touch the green wire to GND, then release the blue again. Usually, the blue LED on the module will blink on
wire. You can even touch the green wire to the blue wire and off in “run” mode, but will only briefly flicker once
(while it is against GND) to ensure everything happens in in programming mode, so if the LED is blinking, you may
not be in programming mode.
the right sequence.
We’ve found that uploading to the ESP8266-based deAnother trick you could use if you want to make the setup more permanent is to (carefully!) glue the sockets that vices is sometimes less reliable than other devices, so it
are plugged into the ESP-01 together to form a single large may simply be a case of trying a few times.
socket which can be removed as one piece from the ESP01. If you are using a cyanoacrylate type adhesive (Super Set-up
With the sketch completely uploaded to the device,
Glue), gently separate the sockets to allow the glue to penetrate, apply a small amount away from the ESP-01, then open the Serial Monitor at 9600 baud (you can do this
via the Tools menu or, in Windows, the key combination
firmly squeeze them together until the glue takes.
Now, having built our programming rig, we can upload CTRL+SHIFT+M). The program will transmit its current
baud rate at 9600 baud before running, so if you see a differthe code to the ESP-01.
Click Sketch Upload in the IDE and while the sketch is ent number or garbage output in the Serial Monitor, check
the displayed baud rate and use that instead.
compiling, touch GND to the blue wire, then green and then
Within a few seconds, there should be a stream of data
release green and release blue. The ESP-01 will stay in programming mode until it is reset or a sketch is successfully on the screen, similar to Fig.8. The lines beginning with
“$GPRMC” and “$GPGSA” are our emulated GPS (NMEA)
uploaded, in which case it will run the uploaded sketch.
Any errors will appear in the bottom pane of the Ardui- data, while the “$ESP82” lines are debugging informano IDE window. If you get errors like “error: espcomm_up- tion so that we can follow what our NTP-based GPS Time
load_mem failed”, this is because the computer cannot send Source is doing.
These two groups of three lines show the data from a
data to the ESP-01. In this case, try the blue/green sequence
Fig.8: sample output from the completed NTP/GPS Adaptor
unit. The GPRMC, GPGGA and GPGSA sentences mimic
those produced by a GPS receiver (hence the GP prefixes)
while the ESP82 sentence contains our debugging data.
You can see that the unit acquired a WiFI IP address
(192.168.43.252) between the first and second instances.
siliconchip.com.au
Fig.9: the NTP GPS Source set-up menu.
Celebrating 30 Years
April 2018 63
Parts list – NTP Time Source
1 D1 Mini ESP8266 module [eg, Jaycar XC3802] or
1 ESP-01 module [eg, Cat SC3982 & Altronics Z6360]
To program the ESP-01, add:
1 USB/serial converter
[eg, SILICON CHIP Online Shop Cat SC3543]
1 small breadboard
2 10kΩ 0.25W resistors (1% or 5%)
2 male-to-male jumper wires (to suit breadboard)
11 male-to-female jumper wires (to suit breadboard)
configured module that has already connected to a WiFi
network. You can see that it updates its time, latitude and
longitude between the first and second group of sentences
(it really is that quick!).
You will probably see something that looks like the first
group repeated, as your unit will not be connecting to a
WiFi network just yet.
To enter the configuration menu, type “~” and press
enter on the Serial Monitor. You will need to have the
serial monitor set up to produce carriage return (CR) or
carriage return/line feed (CR/LF) at the end of each line,
as the menu looks for CR on some commands; this happens by default.
The menu will appear, as shown in Fig.9. You will need
to configure options three and four to suit your local WiFi network by pressing “3” and Enter, followed by your
WiFi network’s SSID name and then press Enter. Then
type “4” and Enter, followed by the password and Enter.
As you might imagine, the password is saved in a nonsecure fashion and can easily be viewed by anyone who
has access to the module, so be careful who you give it to.
The NTP server and dummy coordinates should not
need to be changed but this can be done in a similar fashion if necessary.
The dummy coordinates correspond to Sydney, so
should be a good default if you are using the High Visibility 6-Digit LED GPS Clock in Victoria, NSW or ACT. If
you are using the GPS-synchronised Analog Clock Driver, these don’t matter, as the time zone is set in the PIC
on the driver PCB.
In any case, the unit should get a reasonably accurate
latitude and longitude from the IP web service. It’s only
in the case that this fails that the defaults are used.
Finally, press “9” and then Enter to save, then press the
reset button on the side of the D1 Mini to load the new
defaults. You should see a valid IP address appear after
the second comma of the “$ESP82” sentence if the WiFi
connects successfully. See Fig.8 for more detail on this.
Checking the “$GPRMC”, “$GPGGA” and “$GPGSA”
sentences should reveal valid data, including the current
(UTC) time and date after “$GPRMC”. If everything seems
to be working here, we can connect it up to our clock.
The D1 Mini also has an onboard LED to help set-up and
troubleshooting. While it is looking for a WiFi network
at start-up, the LED is on solidly – so if the LED lights
up and never goes out, the unit is not connecting to your
WiFi network. After this, the LED will blink every time
data is transmitted, which should be once per second.
64
Silicon Chip
Configuring the ESP-01
As well as needing the right combination of pull-ups
and pull-downs to be programmed, the ESP-01 will also
need to be configured to run correctly before connecting it
to a clock. Fortunately, this is easily done by adding solder
bridges to some of the pins to connect them to the correct
voltage levels.
Soldering the pins simply prevents the ESP-01 from entering programming mode, so it can still be configured via
the setup menu on the serial port if necessary.
Carefully run a bridge of solder between the 3.3V pin
(the top left pin when looking at the top of the board, pins
at the top), CH_PD, RST, GPIO2 and GPIO0 (the four centre pins). This effectively forces the ESP-01 into run mode
every time it is powered up. We found it easiest to bridge
out the four centre pins, then tilt the module to allow the
bead of solder to reach the 3.3V pin.
See the photo below for how the ESP-01 should look
after it has been bridged. Alternatively, you could solder
a couple of short lengths of hookup wire to join the pins.
To connect it to the clock, plug jumper leads into 3.3V
(top left), GND (bottom right) and TX (above GND). From
now on, the ESP-01 can be treated like the D1 Mini and
these are the only three connections you need. Note that
with the ESP-01 module, the blue LED is connected to the
TX pin, so it will flicker to indicate data is being transmitted
but will not solidly stay on while the module is attempting
to connect to WiFi as with the WeMos board.
Connecting to the GPS-synchronised
Analog Clock Driver
There are only three connections needed to work with
the GPS-synchronised Analog Clock Driver from February
2017: power (3.3V), ground and the serial data. Remove
the battery from the Clock Driver, ensure that JP1 is set to
the 3V position, then wire the unit up to the GPS module
header. See the top photo opposite for details.
This means connecting the 3.3V pin on the D1 Mini to
the VCC pin on the clock, Ground (“G”) to GND and TX to
TX. We used jumper socket lead off-cuts to wire up our D1
Celebrating 30 Years
Bridging the pins of the
ESP-01 with solder forces
it into “run” mode and
prevents it stalling in
UART upload mode. With
a bit of care and a solder
sucker, the solder can be
removed and the ESP-01
can be reprogrammed
if necessary. The pins
that are bridged are
VCC, CH_PD, GPIO0,
GPIO2 and RESET.
The copper tracks
at the bottom of the
PCB are the onboard antenna.
siliconchip.com.au
Mini, so it’s easier to remove in future if necessary (for example, if we need to configure it to a different WiFi network).
You’ll see in the photo that we’ve actually connected
3.3V to the “EN” pad on the PCB, because it’s directly connected to VCC on the reverse of the clock PCB and it means
that the wires don’t need to cross.
Set the hands of the clock to 12, and re-insert the cells.
You should see the STARTUP LED on the Clock Driver
flash once, then twice as it powers up the D1 Mini. If the
D1 Mini’s LED does not light, check the wiring connections.
The LED should go out again in a few seconds as it connects to WiFi, and provided the Internet connection is good
and the NTP servers are online, the STARTUP LED on the
Clock Driver will flash four times and it will start doublestepping towards the correct time.
Connecting to the
High Visibility 6-Digit LED GPS Clock
The set-up for the High Visibility 6-Digit LED GPS Clock,
from the December 2015 and January 2016 issues, is similar to that for the GPS-synchronised Analog Clock Driver.
Because our prototype unit did not have a 1PPS output
(and it is not required by the clock), we did not connect
it. If you need it, it’s on pin D2 of the Mini.
Ensure that LK1 is set to the 3.3V position and connect
+V to 3.3V on the D1 Mini, GND to G and TX to TX, as
shown in the photo below.
Power on the clock, and after a few seconds, you should
see the GPS display indicating that the clock is awaiting
a valid GPS signal. Once valid data has been received by
the clock, it will go to the normal clock display. Since
this clock uses latitude and longitude to set the time
zone, incorrect data here may lead to an incorrect time
being displayed.
If you find the time is incorrect (especially if it is out
by a whole number of hours), the NTP-based GPS Time
Source may not be providing correct latitude and longitude data, in which case the dummy values may need to
be changed.
The NTP-based GPS Time Source updates its time from
the NTP servers every hour. We’ve tried to program it so
that it won’t “jump” when that happens; in fact, you probably won’t notice it. But for the first few
hours, as the drift compensation will
not be operational yet, you may notice
an occasional slight glitch in the time.
Only three wires are needed to connect the D1 Mini to
the GPS-synchronised Analog Clock Driver (Feb 17) and
although slightly larger than the GPS Module, the D1 Mini
is a great fit for the PCB.
the US government, and it was a server we tried while testing the NTP-based GPS Time Source. In practice, because
the servers are so far away, the round-trip time for our data
was too long to maintain accuracy, so a closer server was
chosen at pool.ntp.org
This server is actually a large number of servers around
the world and the internet’s DNS system tries to point you
to a nearby server.
The server can be changed via the configuration menu
by pressing “5” and enter, then entering the URL or IP
address of the new server.
SC
Using it with other clocks and
NTP servers
Any device that uses GPS data as its
clock source should be able to use this
project. With NTP being used so widely,
the time provided is quite accurate and
the three connections for power, ground
and data are usually easy to find.
The default NTP server used in our
sketch is actually provided by volunteers
who donate their server time to make
NTP widely available. See http://www.
pool.ntp.org/en/ for more information.
As always, servers on the internet may
come and go, and there are alternatives.
For example, nist.time.gov is provided by
siliconchip.com.au
Using a row of header pins makes it much easier to connect our completed
unit to the clock. In this case, we only need three pins.
Celebrating 30 Years
April 2018 65
saVE $50
dEal oF thE Month!
Z 6450
Build It Yourself Electronics Centre®
Construct - Code - Program
april
139
$
M 8990A
This new multimeter is built tough
with water and dust resistance,
plus a impact resistant case for the
rough and tumble of every day use
in the field. Auto ranging design
offers a feature list as long as your
arm with a clear large digit backlit
display. Includes carry case & test
leads. See web for full spec list.
159
saVE
$40
$
saVE $20
89
$
An obstacle avoidance tank robot which can be
modified, tweaked and upgraded as you level up
your skills with Arduino. Features a solid pair of
tracks with aluminium & acrylic base. Bluetooth
smartphone control. Great for young builders
looking for a challenge! 12+
24.95
$
Rugged Digital
Multimeter.
Built like a tank!
Q 1069
Bluetooth® Arduino
Smart Tank Kit
K 9675
MegaStand Acrylic
16x2 LCD UNO Kit
89.95
$
nEw!
Replacement Laptop Supply
Lost your laptop power supply? Or need an extra one
for the office? This unit includes mains lead and 10 tips
to suit popular models of laptop. Voltage output is set
automatically. 5-24V <at> 90W max.
A cut down version of our popular MegaBox which provides a backlit
16x2 LCD for simple readouts, plus room to customise the front panel
with buttons or IR sensor. UNO (sold separately) fits neatly behind the
screen and provides room for add-on shields as required.
29.95
$
saVE $14.95
D 2815
A 4201
199
T 2120
nd
Midla
This workbench essential is just the shot for electronics
projects, crafts, hobbies and odd jobs around the house!
Powerful 130W motor with variable speed between 8000
and 33000 RPM. Included is a 172pc accessory kit of
grinding wheels, drills, cutters, sanding discs, polishing
pads and more! Stows away in a hard plastic carry case.
saVE 15%
DS
AL
ON
BUNNINGS
CD
M
LEACH HIGHWAY
GT. EASTERN HWY
75
$
5A 116 North Lake Rd.
16.95
$
Handy USB Soldering Iron
Powered by a USB port! Great for occasional jobs like fixing a dry joint.
Built in handle switch and auto sleep mode ensures safe operation.
Includes stand & USB lead.
A 0345
39.95
$
waterproof design
D 2039
Brilliant Wireless Bluetooth® Sound
MYAREE
T 2699A
COPE ST
E
LOTON AV
MIDLAND
GATE
LLOYD ST
NORTH LAKE ROAD
MCCOY ST
ee
nEw!
Cut, Polish, Grind, Sand & Carve!
NEW WA stores now open!
Myar
60
$
nEw!
$
This 2.4GHz wireless presenter
replicates PowerPoint slide controls
in your hand. Plug and play, no driv- D 4238
ers required for Mac or Windows.
includes laser pointer!
Includes battery.
$
Stream audio directly from
your device to your speakers
in the study or entertaining
area. 3.5mm and RCA inputs.
Class D design with Class
AB performance.
Includes internal
headphone amplifier.
34.95
Make your next
presentation easy!
Stream direct to your TV from your favourite services
such as Netflix, Stan, YouTube and more! Capable of
streaming stunning 4K videos <at> 60fps! Requires 2A
USB power supply. Pair it with our A 0981 wireless
keyboard/trackpad for $29.95.
Bluetooth® 2 x 50W
Mini Amplifier
Add light
instantly!
A stylish motion activated
light for paths, driveways,
garden sheds etc. Charges
by day, lights at night.
Requires no batteries or
cabling - just screw it to
the wall in a sunny spot.
Weatherproof design.
145W x 96L x 75Dmm.
X 2375
nEw!
All your home
entertainment in one box.
nEw!
MIDLAND
212 Gt Eastern Hwy.
Ask for a demo in-store. Great for the outdoors, fits into
your backpack with ease. 5 hr playback time with 4000mAH
internal battery bank. Includes USB lead for easy charging
(M 8862 USB wall charger, $16.95) 268x70x100mm, 840g.
To find your nearest store, visit: www.altronics.com.au/storelocations
Remote Control Power Saver Kit
Allows you to cut standby power use by switching appliances off at
the wall. 30m working range - even behind cabinets or desks. Max
2400W per outlet. Requires 2xAAA batteries (S 4955B $3.95).
Sale pricing ends April 30th 2018.
top ElEctronics workbEnch dEals!
also available in
kits with carry
case & extra tips.
89.95
T 2090
$
59
.95
$
nEw!
nEw!
S 8747
take snapshots
& record video
top buy for the
beginner or
student.
Bargain 40W Soldering Station
The pefect balance of value for money and features for beginners
or cash strapped students and enthusiasts. Slim, lightweight nonslip handle with tip cleaning sponge and iron safety holder. Full
range of spare tips also available.
Great for diagnosing problems in hard to reach places, this handy
camera has a 2m lead with 2 megapixel camera, viewable on your
phone or tablet screen. Connects up to 4 devices at once. LED
camera light provides a clear view. Includes hook, magnet & mirror
attachments. *Phone for illustration purposes.
saVE
17%
39.95
saVE 22% this Month
Handy Wi-Fi Endoscope Camera
$
any 2 for
24
$
T 1090 0.5mm
T 1100 0.8mm
$39.95
$55
30
42
$
T 2595 70W
$
T 2590 80W
$79
$119
60
$
$
T 2598 100W
saVE
20%
T 1110 1.0mm
T 1122 1.6mm
Protect devices from static damage!
Quality Resin Core Solder
92
This ESD safe matting is a workbench essential!
Generous 1m x 0.5m size with anti-static wrist strap.
Premium grade for leaded soldering.
200gm reels. 60% tin, 40% lead.
X 0432
T 2630 125W
Iroda® Portable Soldering Tools
No More Eye Strain!
An iron for every occasion! T 2595 & T 2590 are ideal for
general purpose soldering and occasional repairs. T 2598 and
T 2630 are great for field techs. Plenty of power and capacity
for bigger soldering tasks. All can be converted into a flameless
heat gun, hot knife or blow torch with additional tips.
This jumbo 5x loupe with LED
lighting provides a crisp clear
view of fine print, circuit boards,
small parts etc. USB rechargeable.
Includes carry case.
T 2247A
Digital Vernier Calipers - for a precise measurement every time!
Perfect for measuring small components, leg pitches etc. 150mm length, suitable for
measuring internal & external depth. 0.01mm, 0.0005” and 1/128th” display.
saVE $170
Compact
30V Lab Power
Supplies
549
$
saVE $100
wide voltage range and
high current output!
185
M 8310 20A
299
$
High Current Lab Power Supplies
Fixed 13.8V 20A Bench Power Supply
30V bench top power supply for use in servicing, repair and design.
The low noise switchmode design offers excellent regulation for high
current requirements. Offers the flexibility of both wide adjustable
voltage & current range. Size: 336W x 87H x 214Dmm.
A fixed voltage output power supply designed for powering automotive, marine and comms equipment. Low noise and ripple
design (<100mV) offers excellent efficiency and performance.
Detect lethal
AC voltages
instantly.
34.95
$
T 2162
‘Getting Started’ Electronics Kit
Great for enthusiasts and students. This handy kit is supplied
complete with carry case and includes all you need to get
soldering! • 30W soldering iron & stand • 2m solder • Solder
sucker • Pliers & side cutters.
39.95
nEw!
Q 3003
M 8303 3A
M 8305 5A
109 $139
$
nEw!
39.95
This non-contact
probe detects cabling
and power outlets
with live AC power
(100-1000V). An
essential preven tative
tool for trades people.
Waterproof case with
in-built torch.
$
saVE
$50
Great for servicing,
repair and design
of electronics. Low
noise switchmode
design. Fine & coarse
voltage and current
controls. Size:
85Wx160Hx205Dmm.
M 8312 30A
nEw!
$
40
$
saVE 27%
bEnch powEr salE!
M 8254
38
$
T 4021
$
T 2186A
101 Pc Ratchet Driver Kit
A tool for every occasion! Features 95 security,
philips, pozi and slotted bits made from tough S2 alloy.
Includes two way ratchet handle with comfy rubber
grip. See web for full contents list.
Shop online 24/7 <at> www.altronics.com.au
1500W
Heat Gun
Perfect for
heatshrink - shrinks
evenly without
burning. Also shifts
paint, solvents from
surfaces, makes
plastics malleable
and more! 450L/
min airflow.
saVE 20%
T 2110
39
$
1300 797 007
GadGEts to MakE YoUr liFE EasiEr!
Ideal for the games room, patio
or alfresco area! Wall mount
bracket makes installation
a breeze. Aluminium grills.
130x105x170mm.
1.8kg. Sold in pairs.
saVE $30
139
includes air compressor
& ultra compact lithium
jump starter!
$
30W 2-Way
Wall Speakers
M 8198
129
$
LED Strip Light Camping Kit
Inflate a flat tyre. Start a flat battery.
A complete auto rescue kit for the car boot. Features a 16800mAh
battery bank plus emergency compressor to top up tyres (max 8
mins run time). Provides 600A peak cranking output for cars with flat
batteries. 12/16/19V & USB output provided for powering devices.
Great for setting up temporary lighting in tents
and campsites. Yellow light reduces insect
attraction. Secure it with the included hook and
loop ties and plug it into 12V power (car adaptor
included). It’s a great work
light or dim it down
for a reading light.
saVE $10
Water
resistant.
55
$
X 3260
D 0505A 1A 4000mAh
nEw!
24.50
$
31
.95
$
nEw!
D 2326
This ultra-slim pad suits Qi wireless charging enabled devices
(such as the iPhone 8 & X). Includes USB cable, requires USB wall
charger, such as M 8862 $16.95. *Phone for illustration purposes.
D 0507A 2A 8000mAh
Super Slim Battery Banks
nEw!
99
$
PB7309
20m
135
$
PB7311 30m
Long Distance
HDMI Sender
As used by hundreds of
commercial AV installs!
Send 1080p from a HDMI
source up to 50m over
Cat5e/6 UTP. Includes TX,
RX & plugpacks.
saVE 10%
125
$
saVE $30
Upgrade your alarm clock to digital radio
More channels, more choice. The ideal bedside companion to
wake up to your favourite digital or FM station. Large colour TFT
display shows time and scrolling digital radio information. (displays
analog clock and date when radio is off). 20 channel presets. Two
alarm times. Size: 135L x 110W x 90Hmm
saVE $40
185
$
S 9437
Instantly add Bluetooth wireless audio streaming
to any 3.5mm input, whether it be your car, your
favourite headphones or home amp. Internal battery provides 5 hours of listening time and is USB
rechargeable. Just 40mm long!
79
$
saVE 20%
40
A 3087B
D 2359
nEw!
USB C to HDMI Adaptor
29.95
A 3216A
$
69.95
$
119
$
saVE 18%
Latest technology cables
fitted with booster
unit to allow for
longer cable
runs. Plugs and
booster fit down standard
25mm electrical conduit.
$
A 1101
Bluetooth 3.5mm Jack
This high spec recorder captures
every minute you’re driving in full
1080p HD, plus motion detect
and parking monitor modes allow
footage recording even when
you’re not driving! Features:
• 2.7” LCD screen • Selectable white balance, exposure,
dynamic range, resolution,
audio recording.
• Optional second
720p camera
(S 9438 $54.95).
• Optional GPS for
Google maps
integration (S 9439
$44.95).
Run HDMI over
longer lengths!
33.95
Instant recharge for your phone. Slimline
aluminium design, fits easily in your pocket.
Protect yourself
with a dashboard
camera.
saVE $40
$
Say goodbye to charging cables!
A 2795
C 0900 White
C 0901 Black
Provides USB A & HDMI output up to
4K <at> 60Hz for USB C devices.
3 Way HDMI Switcher
A handy HDMI switcher for
connecting up to 3 HDMI sources
to a 4k/2k or HD display.
top ValUE pa GEar...
saVE $120
179
$
A 2554
Top Value Redback 5 Channel Audio Mixer
®
A 0920
saVE $20
Control AV gear up to 200m away!
Use your remote control up to 200m away (line of
sight) from your equipment. Perfect for controlling
your AV system from the patio or entertaining area.
Includes plugpacks, IR emitter & receiver.
saVE $24
85
$
D 5584
Wi-Fi audio streaming for any amp!
This brilliant music streamer simply plugs into your
existing amplifier’s RCA/3.5mm input and pairs
with your smartphone or tablet for instant high
quality audio streaming. Can be networked into a
multi-zone system for control by multiple devices.
Compact & easy to use mixer. 5 channels accept up to 11 inputs. 3 band
EQ, channel volumes, crossfader & VU meters. Great for schools and
small venues.
239
Instant,
powerful PA
sound for big
crowds!
An all in one portable
PA sound system with
amplifier that sets up
in just seconds - no
expertise required. Just
plug into 240V power,
switch it on and connect
a mic. USB playback
makes it easy to play
your favourite tunes.
Great for clubs, sports
events, fetes, carnivals
and bingo nights!
Shop online 24/7 <at> www.altronics.com.au
$
C 0993
10” 180W
175
$
C 0991
8” 100W
saVE
$60
1300 797 007
nEw proJEct parts...
U-Blox Neo-6M GPS
Module & Antenna
Add GPS location to your
Arduino/Pi project, aircraft
or drone. 3.3/5V logic level.
Includes 6x20mm ceramic antenna.
Also available as an
Arduino shield with
active 28dB antenna
(Z 6332 $69.95).
26.50
89
$
$
Z 6315
ESP32 Wi-Fi/
Bluetooth/BLE
Module
saVE $20
Includes a huge array of sensors, parts, LEDs,
jumper wires, even an LCD screen!
HiFiBerry®
The Audiophile Add-On
for Raspberry Pi
Z 6402
129
Amp+ HiFiBerry
60W Amplifier Module
Z 6405
A high-quality, highly efficient Class-D power
amplifier offering up to 60W output. Ideal
building block for multi-room audio designs.
Just connect speakers & power up the Pi
to listen! Case to suit DAC & Amp H 6406
$38.50.
B 0091
The HiFiBerry DAC+ is a highresolution digital-to-analog converter. This
is a special sound card for the Raspberry
Pi optimized for the best possible audio
playback quality. Case to suit DAC & Pi
H 6410 $30.50.
4 for
$
79
26.95
$
K 9705
160
LC Meter Shield Kit
$
Plugs into an Arduino UNO to provide high
accuracy inductance and capacitance measurement. 5 digit resolution, 1% accuracy.
10nH to 100mH+. 0.1pF to 2.7µF+.
Silicon Chip Stereo Hifi Valve Preamplifier Kit
Very low distortion for a valve pre-amp with very high SNR of
105dB. Easy to build, with the preamp & power supply on one
board. Includes 12VDC 1A plug pack. *Acrylic box sold separately
(K 5193 $34.95). Uses Electro-Harmonix 12AX7.
12
$
nEw!
ProtoHAT for Raspberry Pi®
This decade box kit simulates resistance values between 1R and
10M - quick and easy way to find the optimum value for your circuit design. Pocket sized, accurate and reliable.
saVE 33%
A HAT board with soldermasked 0.1” holes
and stackable header so you dont lose access
to the GPIO pins. Slots included for display &
camera cables. Pi sold separately.
35
Easy to build!
$
saVE 22%
K 5350
K 5181
59
$
‘Classic-D’ Amp Module Kit
A rugged and reliable Class-D audio amplifier
producing up to 250W into 4Ω. Class-D
amps are commonplace amongst consumer
equipment offering high power and efficiency.
Low distortion <0.01%. K 5182 optional
speaker protector $19.95.
(SC April ‘17) This two spring tank type reverb unit provides
reverberation effects for your guitar/instrument. Adds
complexity and depth to your sound. Easy to build into
other projects with 9-15VAC or 12-15VDC power.
K 9805
saVE 20%
Z 6510
Temperature
Alarm Kit
Ideal for use with home
brew, aquariums, heating
& cooling etc. -33°C to
125°C range. Under/over
indicators with piezo alert.
12.95
$
Heart Rate
For Arduino Kit
A simple kit design for biometric
Arduino projects - or anything
where measuring a heartbeat is
required. Requires 9V battery
(S 4970B $3.95)
Add a spring reverb to
your favourite guitar amp.
Phone: 1300 797 007 Fax: 1300 789 777
Mail Orders: mailorder<at>altronics.com.au
This handy kit makes one
210x110mm digit and can be
paired with additional digits to
create a clock, number counter
etc. Red high brightness LEDs.
Driven by Arduino ShiftOut.
Z 6307
Choose the right resistor every time!
Sale Ends April 30th 2018
Build your own jumbo
clock or counter
nEw!
K 7515
$
Z 6400
$
K 9680
saVE 15%
65
14.95
nEw!
Pefect for Arduino based access control,
security and automation designs, this
handy wallplate has the atmega328p
chip on board and is suitable for use
with standard shields.
saVE 28%
42.95
$
DAC+ RCA
HiFiBerry Module
Arduino Keypad Plate
$
nEw ModEl!
nEw!
nEw!
K 5192*
The Digi+ is a high-quality S/PDIF output
board add on. It offers a dedicated S/PDIF
interface chip supporting up to 192kHz
24bit resolution. Optical & coaxial output.
Case to suit Digi+ & Pi H 6410 $30.50.
24.95
$
Z 6221
A popular high precision
ADC for microcontroller
designs with 860 samples/
sec over I2C. 2-5V input.
saVE $35
Digi+
HiFiBerry Module
Z 6333
bUild it YoUrsElF & saVE...
saVE 10%
65
K 9650
Analog-to-Digital
ADS1115 16 Bit
Converter
HiFiBerry adds high-quality sound to your
Raspberry Pi. HiFiBerry sound cards are
designed for optimal sound output quality.
It is the ideal solution for all Raspberry Pi
users that love music. HiFiBerry boards
are compatible with Raspberry Pi A+, B+,
2B and 3B.
$
59.95
$
Z 6347
Provides 2.4GHz Wi-Fi and
bluetooth on board for projects
requiring wireless control/
data transfer. Requires SMD
soldering for assembly.
165pc Arduino Parts Pack
nEw!
29
$
24
$
K 1137
saVE 40%
Find your nearest reseller at:
www.altronics.com.au/resellers
2.8” Touchscreen Shield
A 240x320px touchscreen shield for
Arduino utilising the ILI9325 chipset.
3.3V input.
Please Note: Resellers have to pay the cost
of freight and insurance and therefore the
range of stocked products & prices charged
by individual resellers may vary from our
catalogue.
© Altronics 2018. E&OE. Prices stated herein are only valid until date shown or until stocks run out. Prices include GST and exclude
freight and insurance. See latest catalogue for freight rates.
A Different Approach in
Digital Hearing Aids:
BlameySaunders’ “Facett”
by Ross Tester
Having worn three different types of their hearing aids since 2011 when
BlameySaunders first entered the market, I was intrigued to find they
were once again launching a completely new model, with a slogan “Hear
Like Never Before”. What could be so different – after all, it’s only been 12
months or so since they introduced their brilliant Opus96 digital models?
T
he first thing you notice when
you open the Facett Hearing
Aids packaging is that the contents look quite different from previous models.
For a start, they don’t come with the
bulky “Sound-N-Dry” storage container with tiny beads that go everywhere
when the bag splits!
Instead, they have what they call a
“Pod”, a portable storage case/drier
which houses the hearing aids themselves. But is much more than a storage case and drier.
70
Silicon Chip
For a start, it has a power socket on
the side – that’s used by the inbuilt
battery recharger.
Battery recharger?
Well, that’s certainly different – the
Facett uses rechargeable battery modules. That on its own is a very welcome change.
Each of the charged cell modules
will give up to 36 hours continuous
use.
Anyone who has used hearing aids
for a while will tell you that continuCelebrating 30 Years
ally buying replacement batteries is
more an inconvenience than a huge
cost – but a cost nevertheless.
For the common “312” size zinc-air
cells to suit the Opus96 (or the “13”
size to suit the Symphony), for a box
containing 60 cells I usually paid about
$25 for relatively unknown brands
and up to about $50 or so for brand
names, so somewhere between 40c
and $1.00 each.
But every now and then (eg, when
I forgot to take a battery pack with me
on holidays!) I had to buy a pack from
siliconchip.com.au
Woolies or Coles to get me through –
and these could be as much as $10-$12
for a 6-pack! $2 each? Ouch!
Incidentally, you can get really
caught out buying hearing aid batteries on-line if you don’t read the “fine
print”: I found a pack of 18 batteries
for $7.57 on ebay – plus $90.14 postage! (That’s only about $5.40 EACH!
Ouch2!).
Zinc-air batteries start discharging
as soon as you remove their sticker,
which allows air to enter and “activate” them. Then they only last a
few days.
Perhaps even worse, the tiny disposable batteries act like a magnet to toddlers – straight into the mouth!
While zinc-air batteries are not supposed to be as dangerous as lithium
cells (which have caused severe injuries and even deaths when swallowed)
I still wouldn’t like to take the chance
of zinc-airs being swallowed.
But back to the Facett: it uses tiny
silver-zinc rechargeable cell modules
which instantly attach, magnetically,
to the hearing aid “core”.
This also causes the tiny contacts
on the cell to mate with the contacts
on the core.
And being magnetic, they will only
attach one way (if you try to put them
on back-to-front they will instantly
“flip” to the right way – driven, of
course, by the strong magnetic field).
You only have to get the cell module close to the core – say 10mm – and
they instantly snap into place.
That same magnet-based connection is used when charging the cells
in the pod. When inserted, LEDs in
the pod flash green as the cells are
being charged, switch to solid green
to show they are charged, or turn red
if there is a problem (eg, cells won’t
take a charge).
There are four charging “ports” in
the pod as well as two “idle ports”
–they (magnetically, again) hold the
cell modules without charging them
– so you can have two charged modules ready for use while charging up
to four modules.
It takes around eight hours to charge
a cell module from flat so overnight is
the go, much like my mobile phone (or
even my electric car!).
The pod is powered, via a portal in
the end, from a 5V source – either a
USB outlet on a PC, tablet or laptop,
or the 5V mains adaptor (supplied).
To connect, a standard USB-to-micro
siliconchip.com.au
Three of the battery modules are shown in charging positions; the left-hand
one is in the “idle port” (for storage). The “core” modules are the hearing aids
themselves – the Red speaker is for the right ear, the bLue speaker for the left.
USB cable is also supplied.
As we mentioned earlier, the pod
also stores, and keeps dry, the two
hearing aid cores themselves, also held
in position magnetically.
To keep the hearing aids dry, a replaceable desiccant clips into the top
of the pod. As with all desiccants, it
warns you not to eat it . . .
Emergency batteries
Having extolled the virtues of the
rechargeable cell modules, what if
you are out the back of Woop Woop
for a few weeks and have no access
to power?
Admittedly, that would be pretty
rare these days, especially with most
cars having 5V USB sockets, or solar
chargers for mobile phones and the
like (which would obviously charge
the Facett hearing aid modules) but
it is possible.
BlameySaunders have foreseen this
situation and will soon have an optional cell module which does accept traditional (size 13) hearing aid batteries.
Celebrating 30 Years
But we have to say this is something
that we wouldn’t be concerned about.
Bluetooth link
Also on the drawing board and
due to go on sale later this year will
be a wireless (Bluetooth) link which,
among other things, transmits audio
from a mobile phone, media player,
etc, direct to the Facett hearing aids.
It will also help in carrying out a
conversation in background noise and
even let you change some of the Facett parameters (volume, for instance)
from a smartphone or similar device.
But as we said, this is in the future.
Physically . . .
The Facett hearing aid, with attached battery, is slightly larger and
heavier than the Opus96: 23 x 7mm
and 2.4g for the Opus96, 31 x 8mm
and 4.0g for the Facett.
While this might sound significant
(particularly the weight), in both cases,
I forget that I’m wearing them within a
few minutes. In fact, that can be a trap
April 2018 71
Straight outa the box . . . or in this case, only the Pod, complete with the Facett
charging dock with hearing aid “cores”, the battery modules (4), the dessicant
(it slots into the circular retainer in the lid) and instructions.
for young players – a few times I’ve
nearly dived into the pool or jumped
under the shower wearing my hearing
aids – fortunately, nearly!
I trialled the gold-coloured Facetts;
they are also available in silver, grey
and charcoal colours. Obviously, the
Facett gets its name from the multifacetted case design.
There is only one control as such on
the Facett but it serves a dual purpose.
It is an up/down volume control when
pressed briefly; hold the toggle button
in and it switches between the normal
(“Everyday”) program and programs
which you enter yourself, such as in
a crowd, or watching sport, or watching TV, for example.
(We’ll look at programming the Facett shortly).
The control reverts to volume when
the Facett is turned off (ie, the battery
is disconnected – there is no on/off
switch as such).
Inside the hearing aid
According to BlameySaunders, the
electronics in the hearing aid are not
overly different to the Opus 96 models released last year.
Those hearing aids were highly
innovative – digital processing (of
course!) with 96 channels, multi-channel adaptive directional microphone
and so on.
I remember saying at the time they
72
Silicon Chip
were a noticeable improvement over
the previous models, which I reviewed
in March 2013.
The main innovation in the new
Facett hearing aids is in the construction and battery connection, and that
IS highly innovative, as mentioned
earlier.
BlameySaunders engineers told
me that given the short window of
opportunity, they’ve used that time
to “up-spec” and tweak the circuitry
and components in the Facetts, making them the best that (current) technology allows.
So the improvements they’ve made
earn the Facetts the title of “flagship”
in the BlameySaunders fleet.
Virtually invisible
One of the advantages of “behind the
ear” hearing aids, with their “speaker in ear” (SIE), is that they are for all
intents and purposes invisible – especially for ladies with longer hair
which may cover the ears (and therefore hearing aid).
Wearing hearing aids is sometimes
equated with “getting old” and many
people are reluctant to admit that, despite what the calendar says!
(The alternative is also true . . . continually saying “eh?” or “waddya say?”
is also a sure sign of deteriorating hearing/ageing!)
From the hearing aid itself, there is
Celebrating 30 Years
a tiny (~1mm) clear tube which goes
from behind the ear to the front and
follows the contour of the ear, with the
miniature (~11mm long x 3mm diameter) speaker at the end.
Some users prefer to simply place
this inside the ear canal; others prefer
to use one of the (supplied) ear tips
which simply slide over the end of
the SIE and lodge the speaker a little
more firmly in the canal.
Personally, I find this has both disadvantages and advantages: I find
the ear tips take a little getting used
to, making me continually think that
there is something in my ear (which,
of course, there is!).
The advantage is that external
sound, which hasn’t been processed
or tailored by the hearing aid, is to
some extent blocked.
This can be a real boon in a noisy
environment/crowd/etc, especially
if you set up a program to tailor the
sound appropriately.
Apart from the half dozen or so
spare tips, in various sizes, supplied
to suit the Facett, different size tips
are available from BlameySaunders.
They recommend fresh ear tips every
4-6 weeks.
Some of the ear tips have holes in
them which allows some “natural”
sound to enter as well as that from
the hearing aids, while other tips are
solid, blocking any sound/noise not
processed by the hearing aid.
The “Everyday” program
Even if you have no intention of
buying hearing aids, you can check
your hearing without obligation using
BlameySaunders’ “Speech Perception
Test”. See the panel “On-line Speech
Perception Test”.
You might be surprised to find that
your “perfect” hearing ain’t necessarily so!
If you do go ahead and purchase
BlameySaunders hearing aids, they
use the results of the Speech Perception Test to program them with the
“Everyday” program your hearing
aids starts with when they are turned
on (you actually hear them say “Everyday”).
Therefore, every “Everyday” program is unique, tailored to your hearing loss. No two people will have exactly the same losses or requirements.
Hearing Loop
By the way, there is a second “prosiliconchip.com.au
gram” automatically loaded into the
Facetts, selected by holding down the
up/down button. That accesses the
“Hearing Loop” or “Telecoil” function.
We covered Hearing Loops in detail
in a DIY series published in September
and October 2010 (siliconchip.com.
au/Series/11) but in a nutshell, a Hearing Loop is a large coil of wire placed
around a meeting room/auditorium/
theatre/church/etc, fed by a relatively
high-powered amplifier.
These loops are designed to allow
the program, service, etc which others are listening to via a PA system to
be directly induced into hearing aids
fitted with the appropriate firmware.
Hearing Loops are now installed in
many, if not most public buildings and
this trend is expected to continue for
the vast majority of new public buildings in the future.
Most hearing loops are installed
in a building hidden in walls, under
floors, etc and where they are present
you will see a blue and white hearing
loop logo.
Often, signs inside the building will
tell you exactly where the hearing
loop is situated – you have to sit inside the loop for it to work with your
hearing aids.
The Telecoil part is slightly different but works much the same way –
this refers to special telephones designed to amplify incoming calls and
This shot gives you
the relative sizes
of the hearing aid
“core” (the right one
in this case with its
red speaker) and
its battery module.
This was about as
close as I could
get them without
them magnetically
“snapping” together.
induce the signal direct to hearing
aids. Again, they are intended for the
hearing impaired.
IHearYou/Incus-M
As we mentioned, the Everyday
program relies on the words you recognised in the on-line test – and while
it’s much better than a tone-based test,
it’s not entirely foolproof.
For example, you might be distracted while listening and miss a word or
two, or your speaker/headphone setup
might not be quite up to scratch.
You only get one bite at the cherry –
or in this case, one listen. And if you
miss it . . .
The analysis software used by
BlameySaunders may well treat this
as a hearing deficiency and adjust the
program parameters accordingly.
In this case, you’ll want to adjust
the Everyday program. Or you might
want to add your own programs to suit
your particular requirements, as we
mentioned earlier. You can add up to
three more programs.
You do this by means of BlameySaunders’ “IHearYou” software (a
free download) in conjunction with
the Incus-M programmer, supplied
with your hearing aids. IHearYou is
available for Windows, Android and
Mac platforms and suits PC, tablets or
smartphones.
The Incus-M is slightly different
from the earlier Incus programmer –
the earlier models have a flexible flat
cable (FFC) which must be inserted
the right way around into the hearing
aids. To be honest, I found this rather
fiddly and despite instructions, managed to insert them back-to-front on
more than one occasion.
The Incus-M has the same magnetic “instant connection” as the battery
modules making instant, positive connection.
Now you just bring the Incus-M cable ends close to the core modules
and they snap into place (red for right
hearing aid, blue for left, just like everything else).
When you’ve done that, you can set
the balance between ears (that’s where
my Everyday program was most deficient) overall volume levels and so on.
Incidentally, we looked at the Incus programmer in some detail in our
September 2014 issue (siliconchip.
com.au/Article/8005). There are a few
updates but overall operation is very
similar.
A few teething problems – or
is it the nut on the keyboard?
The Incus-M programmer with its core connection cables, the USB power cable
above and 230V USB adaptor at right. The Bluetooth module worked perfectly
with my Android phone but so far, steadfastly refuses to talk to my PC!
siliconchip.com.au
Celebrating 30 Years
Even having gone through this procedure last year with the Opus96
hearing aids, I had a lot of difficulty
getting my PC to recognise the Bluetooth “dongle” supplied by BlameySaunders.
Despite spending considerable time
April 2018 73
with Sophie from BlameySaunders
and, indeed, one of their techs actually taking control of my computer remotely from Melbourne (with TeamViewer software), the problem is as
yet unresolved.
I am fairly certain the problem is
at my end, something my computer
doesn’t want to do – even if I sit and
yell at it!
No problem, though, when we tried
the alternative: using my (Android)
mobile phone. It found the Bluetooth
hardware immediately, loaded their
“IHearYou” software and then allowed
me to program the hearing aids easily,
using the Incus-M.
The range of adjustments is quite extensive, ranging from setting the overall volume (using five tones) by sliding
control bars on the phone screen, setting the balance between those tones
in a similar way, adjusting the sensitivity for minimal feedback, changing
the parameters so that certain sounds
wouldn’t be too loud or too soft, and
so on.
This is all quite self-explanatory
once you’re in the software – we’ve
shown a few screen grabs to give you
some idea of what is happening.
Okay, what’s the verdict?
Every time I’ve road-tested a new
model hearing aid from BlameySaunders, I’ve been impressed with the improvement.
Sure, in some cases it’s only little
improvements between models but
those little steps add up to quite a
The home screen on my
Android phone which
gives access to all the other
programming functions.
74
Silicon Chip
significant upgrade – an upgrade well
worth making.
On the Facetts, the first thing I noticed was the feedback (or more to the
point, the lack thereof). I’m not sure
what the engineers have done to make
such an improvement in this area, but
it was really noticeable.
The second was the ease-of-use. I’ve
already covered the battery connection
and charging, and also the single up/
down control – these two things alone
make for a real improvement.
Third is that “pod” – yes, it is the
recharger but it’s also well thought out
for hearing aid storage and drying as
well as recharging.
And the fourth was simply the clarity: they just seemed to make sound
clearer. I’ve commented in the past that
television program voices, particularly female voices and more particularly on UK-originated shows, have
always sounded somewhat muffled
to me. The Facetts have largely overcome that problem.
As far as the improvement of the
Facetts over the Opus96, I’m sure there
was a marginal improvement in the
new model.
Maybe, in the normal course of
events, it might not be enough to convince me to upgrade. After all, even at
the prices BlameySaunders sell their
hearing aids for, hearing aids are certainly not cheap!
But even if it was ONLY that new
rechargeable and so easy-to-use battery system – and the amount of money I would save by not forever buying
Selecting Balance Loudness
reveals these five tone bars
– simply slide them along
until they all sound level.
throw-away batteries – I’d upgrade to
the Facett hearing aids in a heartbeat!
It really is that much of a breakthrough!
And they look pretty fancy, too . . .
What’s in the box?
When you receive your Facett kit,
you’ll not only find the two hearing
aid cores, four rechargeable battery
modules and the charger/storage Pod,
but the Incus-M programmer will also
be included (elsewhere, if such a device is offered at all, it can be several
hundred dollars extra).
Along with this, there is a selection of ear tips, wax-stop plugs and
cleaning equipment plus, of course,
instructions.
And speaking of instructions, if
there is anything that’s not overly clear,
I have to report that the phone assistance is outstanding!
They patiently took me through
some of the less obvious features (eg,
how to virtually eliminate feedback
or how to minimise sudden, sharp
sounds). They were also the ones that
told me about the Telecoil function
which I’d missed completely.
If you go on-line (www.blameysaunders.com.au) in working hours,
the chances are very high that someone will pop up in a chat window and
ask if you need any help (and they do
– help, that is!).
If you’re not sure which hearing
aids you need, they’ll help you with
that decision without applying the sort
of pressure you’d get in a shop-front
hearing aid store to “upsize”, as the
There are some quite
specialised controls under
“Fine Tuning” such as this
“Quieten Sharp Sounds”.
Celebrating 30 Years
Switching programs allows
you to set up (and tailor)
individual programs to suit
your particular needs.
siliconchip.com.au
fast food retailers like to say.
If you just want to browse, or view
information, just ignore the chat.
How much, where from:
If you’ve priced hearing aids lately, you’ll know that many shop-front
hearing “specialists” (and they seem
to be popping up everywhere!) can
quote you around $12,000 per pair for
good digital models – and often more.
The Facett hearing aid package from
BlameySaunders will cost you exactly
half that amount – $5990 per pair – a
not inconsiderable amount of money,
to be sure, but that is for one of the most
advanced hearing aids on the market.
BlameySaunders still have all three
of the hearing aid packages available
which we’ve reviewed over the years
in SILICON CHIP – the “Symphony” 32
Channel, entry level hearing aid at
$1415 each/$2830 per pair (reviewed
in July 2011 [siliconchip.com.au/
Article/1066]); the SIE-Plus 64 Channel mid-range at $2770 each/$5440
per pair (March 2013 [siliconchip.
com.au/Article/3299]); or the (until now!) top-of-the-line 96 Channel
Opus-96 at $2635 each or $5270 per
pair (May 2017 [siliconchip.com.au/
Article/10653]).
And yes, you can buy individual
hearing aids if (a) you don’t need two
– but BlameySaunders will tell you
that if you need one, the odds are you
do need two! Or (b) you’ve managed
to misplace one – or, as I mentioned
when I reviewed the Opus 96 hearing aids, our schnauzer decided one
looked like a little bone and . . .
Don’t forget, too, that private health
insurance funds usually offer rebates
on hearing aids – the better funds about
$1200; others can be quite miserly!
Checking Your Hearing Online
BlameySaunders maintain that there are five key indicators that your hearing is not all
it should be (or once was!).
(1): You find it hard to follow a conversation in a crowded room or restaurant.
(2): You feel that people are always mumbling.
(3): People complain about the volume you set the TV or radio to.
(4): You find it easier to understand men’s voices than those of women and children.
(5): You often experience ringing or whistling in your ears.
If you recognise any (all?!!!) of these, maybe it’s time your hearing was professionally checked.
You can go to a shop-front hearing aid retailer who will, most likely, put you through
a series of tones asking you to push a button when you can either hear, or not hear, the
tones. From this, they produce an “audiogram” which graphs the levels you can hear at
various frequencies.
The problem with this is it is very subjective: eg,“did I really hear that?” And then follows, of course, the pressure to purchase hearing aids that are often way overpriced!
Everyone in audiology and hearing science is aware of the inadequacies of the pure
tone audiogram. All that tells you is how softly you can hear beep sounds. From there,
the tester has to try and explain why you are having trouble hearing.
The pure tone audiogram’s role should be only the first part of trying to find out the
medical cause of your hearing difficulty – it takes a trained professional to determine
the actual cause.
Instead of pure tones, BlameySaunders developed a “Speech Perception Test”. You
listen to a randomised list of 50 phonemically-balanced English words and type what you
hear in the box provided on screen. They measure the words you hear or miss against
the speech features that make up each word (eg, phonation, resonance, intonation, pitch,
sibilants, vowels, hard and soft consonants etc). This is analysed to give the information
needed to set up your hearing aids but also tells you how much difficulty you have with
the different sounds of speech. This clinically-proven test enables them to generate an
accurate report on the real-world speech sounds you are able to hear.
You can do the BlameySaunders Speech Perception Test online, anytime, without obligation. All you need is a relatively quiet room with good speakers or headphones connected to your PC. The test generates a report which will be emailed to you within ten
minutes or so.
Whether you decide to go ahead and invest in hearing aids after receiving this report
is entirely up to you. If you do decide, they’ll guide you all the way.
Simply go to the BlameySaunders.com.au website and you’ll be greeted with a “Test
Your Hearing” splash screen. From there, follow the prompts.
Where to buy
You can buy on-line from the same
website with a 100% money-back guarantee. Or, if you’re in Melbourne, Sydney or Brisbane, you can book an appointment at any of the BlameySaunders clinics (addresses and even location maps are on the website; all three
are in or near the heart of the cities).
You can also do the Speech Perception Test at those centres and, of
course, have explained to you the different types of hearing aids and their
SC
features.
Acknowledgement: Our thanks to Dr Sophie
Brice from BlameySaunders for her assistance.
siliconchip.com.au
Celebrating 30 Years
April 2018 75
Using Cheap Asian Electronic Modules Part 15: by Jim Rowe
The ESP-01 WiFi
Data Transceiver
The ESP-01 is a very popular WiFi transceiver module based on the
ESP8266 IC; which is designed to allow almost any microcontroller
to connect to a WiFi network. To make this as easy as possible, the
chip is programmed to respond to Hayes AT modem text commands.
As well, the chip can be re-programmed to perform a variety of
different tasks.
W
iFi networking has been around
now for 20 years, after being
adopted as a standard protocol in 1999
– the same year the WiFi Alliance
was formed. Since then it has grown
steadily in popularity, especially in
mobile devices. It’s also quite handy
for wirelessly connecting computers
to routers/modems and peripherals
like printers.
Responding to this growth in WiFi
popularity, in mid-2013, Chinese semiconductor manufacturer Espressif
Systems (based in Shanghai) released
its ESP8266 chip. This is a complete
SOC (system on a chip), combining a
32-bit RISC (reduced instruction set
computer) microcontroller with a full
TCP/IP (internet protocol) stack and all
of the components needed for a WiFi
data transceiver.
But the ESP8266 didn’t really make
an impression in the Western world
until 2014, when another Chinese
firm, AI-Thinker, released its ESP-01
WiFi transceiver module. This was
based on the ESP8266, but what made
it particularly popular was its cost at
less than $4.00.
So the ESP-01 module and the
ESP8266 chip are not new; they’ve
been around for over three years. In
fact, Geoff Graham wrote an article
on using the ESP-01 module in the
December 2014 issue of Silicon Chip,
titled “The $5 WiFi Server”.
76
Silicon Chip
The ESP8266 has since been used in:
■ a WiFi Christmas light controller
(Circuit Notebook, December 2016,
siliconchip.com.au/Article/10486);
■ as a data logger that uploads to the
cloud (September 2017, siliconchip.
com.au/Article/10804);
■ in the Water Tank Level Meter in
the February 2018 issue (siliconchip.
com.au/Article/10963);
■ and most recently, the NTP Time
Adaptor for GPS Clocks that we just
published in this issue.
Those projects actually featured
different modules based around the
ESP8266 chip; there are dozens of
different boards, many of them designed to be compatible with the
Arduino system. Most of the information in this article regarding the
ESP-01 applies equally to those other
ESP8266-based modules.
We are taking a closer look at the
ESP-01 module and ESP8266 chip
here since they have numerous WiFi
Celebrating 30 Years
and “Internet of Things” (IoT) applications.
As an aside, Espressif has recently
released a follow-up to the ESP8266
chip: the ESP32 series, which incorporate WiFi & dual-mode Bluetooth
transceivers and dual-core micros.
Although modules using the ESP32
chips have started to appear, their prices are significantly higher than that of
the ESP-01 at around $9.00. But the
ESP-01 still has some other advantages, such as lower power usage in some
situations. This has renewed interest
in the ESP-01, especially since it’s the
easiest way to get started with WiFi at
the lowest cost.
About WiFi
WiFi is a technology for wireless
local area networking, with devices
complying with the IEEE 802.11 protocol standards. A large part of this is
based on a patent (US5487069) developed at the CSIRO in Australia, by a
siliconchip.com.au
ESP8266 Features
WiFi – 802.11b/g/n
32-bit RISC CPU
512KB-16MB flash memory
HTTP & FTP
IPv4
TCP/UDP
17 GPIO pins
SPI
I2S and Software I2C
10-bit ADC
Fig.1: block diagram of the ESP8266 IC. The left-hand side of the diagram contains
the RF sections while the right-hand side is the baseband and CPU section.
team led by radio astronomer Dr John
O’Sullivan.
The IEEE 802.11 protocol was first
released in 1997 and has since been
revised and updated numerous times.
802.11 is a set of MAC (media access control) and PHY (physical layer) specifications for implementing
WLAN (wireless local area network)
data communication in the 2.4GHz,
3.6GHz, 5GHz, 5.9GHz and 60GHz
frequency bands.
There are many different versions
of the 802.11 protocol. Those that are
most popular for WiFi are 802.11a,
802.11b/g/n and 802.11ac. These
mainly differ in terms of their PHY
specifications, as shown in Table 1.
The ESP8266 chip
The ESP8266 is a self-contained
WiFi networking transceiver and
microprocessor, packaged in a single 32-pin QFN SMD chip measuring
only 5 x 5mm. It operates in the internationally unlicensed 2.4-2.5GHz
ISM (Industrial, Scientific and Medical) band and is compatible with the
802.11b/g/n protocols.
The downside to the 2.4-2.5GHz
band is that it is also used by Bluetooth
devices, microwave data transceivers
using the Nordic nRF24L01+ chip and
also plagued with various sources of
noise like microwave ovens. So this is
a somewhat noisy band, and becoming noisier all the time.
The block diagram of Fig.1 shows
what’s inside the ESP8266. On the
left are the RF sections, including the
transmitting and receiving sections,
the T/R switch, an LNA (low noise
amplifier) and an RF balun for connecting to one or two antennas.
On the right is the baseband section
which includes an integrated 32-bit
siliconchip.com.au
RISC CPU, a memory controller with
both ROM and SRAM, all of the registers and sequencers for implementing
a full TCP/IP stack and interfaces for
SDIO (SD cards), SPI (serial peripheral
interface), GPIO and I2C communication with external MCUs and/or external flash memory.
Incidentally, the RF output power
in 802.11b mode is +19.5dBm, or just
under 100mW. When this output is
being provided in transmit mode the
chip’s current drain from the 3.3V
supply is 215mA, corresponding to
around 710mW.
In receive mode with 1024-byte
packets, the current drops to around
60mA (<200mW). The chip also has
two power saving modes: standby
mode, where only the RTC and watchdog remain active (current <1mA) and
deep sleep mode where only the RTC
remains active and the current falls to
below 12µA. The chip can be woken
up to transmit packets in less than 2ms.
The ESP-01 module
The ESP-01 module is quite small,
measuring only 25 x 14.5mm, including the PCB track antenna and the
8-pin interface connector.
Fig.2 shows the complete circuit
for the latest version (V2) of the ESP01 module and there’s very little in
it apart from the ESP8266EX chip itself, a tiny 26MHz crystal and a 25Q80
1MB flash memory chip. There are two
LEDs, one to indicate when the module is powered up (LED1) and the other
to indicate when serial data is being
transmitted (LED2).
All of the connections to and from
the external micro are made via CON1
at upper left.
The module is designed to operate
from 3.3V and should not be connected
Celebrating 30 Years
The ESP8266 is a low-power, selfcontained WiFi chip.
The main use of the ESP8266 is to
provide a WiFi interface for other
microcontroller devices.
However, the ESP8266 IC is powerful enough to be used as a low-power
computer, combined with being able
to flash the firmware with your own
program code using a bootloader.
It has an extensive API provided on
ROM which implements various timer,
hash (MD5 & SHA1), WiFi and TCP/
UDP functions etc.
A list of API functions can be found at:
siliconchip.com.au/link/aaj4
siliconchip.com.au/link/aaj5
Some potential uses include:
Remote file manager
Web server
Ad-hoc network
Data logger
Baby monitor
What is it?
April 2018 77
Fig.2: complete circuit diagram for version 2 of the ESP-01 module. The PCB track antenna has a range of approximately
300m under good conditions with line of sight and possibly 10m at best indoors.
to a 5V supply. The logic inputs of the
ESP8266EX are not tolerant of 5V, so if
your external micro operates from 5V
the interconnections need to be made
via logic level translation circuitry. We
have read that applying 5V to its input pins does no harm but this is an
undocumented feature and we don’t
suggest you rely on it.
Another point to note is that the
ESP8266EX chips used in the latest
versions of the ESP-01 module (V2) are
programmed to communicate with an
external PC or micro at a default rate of
115,200 bps (baud), while earlier versions were set up for 9600 bps. This
can cause complications when you try
to use the newer ESP-01 modules with
an Arduino Uno or equivalent.
in most versions of Windows, Linux
and macOS.
Note that although the popular USB/
UART bridge modules also provide a
3.3V output, this is generally only capable of supplying 100mA or so. That’s
why you need to use an additional LDO regulator, like the LM1117T
shown, to provide for the higher current levels needed by the ESP8266
when it’s transmitting data packets.
Your PC will be able to communicate with the ESP8266 and hook up to
a local WiFi router and network, using
a standard communications terminal
program like Tera Term. Note that this
won’t give your PC direct access to the
wireless network, since it won’t have a
network driver that understands how
to communicate with the ESP8266.
Programming it directly
While you can use the ESP-01 module purely as a wireless “bridge”, it’s
also possible to program the ESP8266
directly, ie, to run some code without
a separate micro. That’s because the
ESP8266 does have a built-in CPU
of its own, together with RAM and
EEPROM.
In fact, ESP8266/Arduino enthusiasts have come up with a nifty
Connecting to a PC
Interfacing the ESP-01 module with
a computer is quite easy. All that’s
needed is a USB-UART bridge module
to provide a communications link with
the computer (via a USB port) and also
to derive power from the computer via
a 5V-3.3V LDO (low-dropout) regulator
to reduce the supply voltage to 3.3V.
The basic circuit needed is shown in
Fig.3, although we’ve shown two versions of the USB-UART bridge module
– one with a micro USB socket and the
other with a type A socket. Both use
the popular CP2102 chip, for which
there’s a VCP (virtual COM port) driver
78
Silicon Chip
Fig.3: if you want to connect the ESP-01 module to a computer, all that’s needed
is a USB-UART bridge like the CP2102 and LDO regulator to reduce the USB
port’s 5V supply voltage to 3.3V.
Celebrating 30 Years
siliconchip.com.au
Arduino board package which allows
the ESP8266 to be programmed via
sketches written in the Arduino IDE,
using standard Arduino functions
and libraries. Information about this
Arduino “core” is available at https://
github.com/esp8266/Arduino
Using it with an Arduino
Connecting the ESP-01 module to an
Arduino is a little more complex than
you might expect, mainly because of
the need to power the module with its
own 5V-3.3V LDO regulator and also
because logic level translation circuitry is needed to interface between the
module and an Arduino’s I/O pins.
The easiest way to do this is to use
a WiFi module interface shield like
the Freetronics ESP1SH, as shown in
Fig.4. The shield mounts on the top
of an Arduino and provides an 8-pin
header socket for plugging in an ESP01 module and an LD1117 3.3V LDO
to power the module plus logic level
translation circuitry for the TX and
RX data lines.
There’s also a pushbutton switch
(S2) for reprogramming the ESP-01’s
flash memory, another pushbutton
switch (S1) to reset both the ESP-01
and the Arduino together and most
importantly, an 8-way-by-3 header
strip which allows you to link the level
shifted ESP-01 TX and RX lines to one
of eight possible pins on the Arduino.
An enlarged
view of the latest
ESP-01 module.
It features a few
SMD components
including a 26MHz
crystal and 1MB
of flash memory.
The GND pin is at
the top-right of the
PCB, while Vcc is
at the bottom-left.
Link header
That link header on the ESP1SH
shield is important because of the
point mentioned earlier, about the
latest ESP-01 modules being programmed to communicate at 115,200
bps. This a problem with the Arduino
Uno and its clones because the ATmega328 CPU used in these modules
has only one hardware UART, which
is normally used for communication
with the PC via the onboard serial/
USB bridge.
To communicate with another serial
device like the ESP-01, you need to use
a software-driven serial port with a different pair of pins for the TX and RX
lines. But these software-driven serial
ports can only operate at a maximum
speed of 38,400 bps.
But there is a workaround. First,
you download a do-nothing sketch
to the Arduino and set it running, so
that it ignores the hardware UART
temporarily.
Then connect your ESP-01 module
siliconchip.com.au
An enlarged photo of the silicon die and metal layers of an ESP8266 (a variant of
the ESP8089). The RF section is at upper left and takes up a larger portion of the
chip. The area below and right is memory while the I/O pads are along the edges.
https://zeptobars.com/en/read/Espressif-ESP8266-wifi-serial-rs232-ESP8089-IoT
Celebrating 30 Years
April 2018 79
Fig.4: connecting the ESP01 module to an Arduino
via the Freetronics ESP1SH
shield. The benefit of
using this shield is that it
provides a 8-pin header
to plug the module into,
handles the level shifting
from 5V to 3.3V, and logic
level translation circuitry
for the transmit and receive
pins.
However, this of course is
not the only way to connect
the ESP8266 to an Arduino.
to the same hardware UART RX and
TX pins (D0 and D1). You can then
reprogram the ESP-01 directly from
the PC so that it defaults to a data rate
of 38,400bps or less, making it compatible with the software serial port.
Then reconnect the ESP-01 TX and
RX lines to a different pair of pins on
the Arduino and set those up as a software serial port.
Alternatively, you could simply use
the hardware TX and RX pins to communicate with the ESP-01 with the
limitation that you must disconnect
it when re-programming the Arduino
board. This will limit your use of the
Serial Monitor for debugging, though.
Things are a lot easier if you use an
Arduino Mega, Mega 2560R, Freetronics EtherMega or the Duinotech
Mega, because these all use either the
ATmega1280 or 2560 processors, both
80
Silicon Chip
of which have a larger flash memory
plus an additional three UARTs. Each
of these can provide a serial port which
operates at 115,200 bps or more.
The ESP1SH shield’s header strip
allows you to link up the ESP-01’s TX
and RX lines to any serial port you
wish, without the need for reprogramming. In the case of the Mega2560R,
all you need to do is connect the ESP01 TX line to pin 19 (RX1) and the
RX line to pin 18 (TX1) using a pair
of short male-to-female jumper leads.
This is shown in both Fig.4 and the
photo at right.
We’ll look at what’s involved in programming an Arduino Mega to use the
ESP-01 module for WiFi communication shortly. In the meantime, let’s
look at how the ESP-01 can be linked
to a Micromite.
Connecting a Micromite?
How to connect an ESP-01 module
Celebrating 30 Years
to a Micromite is shown in Fig.5. Note
that we still need to use an LM1117T
LDO regulator to provide 3.3V to the
ESP-01, since its current drain is somewhat higher than that available from
the Micromite’s own 3.3V regulator.
But the TX and RX lines from the ESP01 can be directly connected to the RX
and TX pins of the Micromite, since
no level translation is needed.
There’s no problem with data rates
either, providing you use the connections shown, which use the Micromite’s hardware UART port (COM1).
This can operate at 115,200 bps without any problems, provided you are
running the Micromite at a clock
frequency of 40MHz (the default),
50MHz, 30MHz or even 20MHz.
WiFi via the ESP-01
Because the ESP8266 chip in the
ESP-01 module is designed to communicate via standard Hayes AT modem
siliconchip.com.au
Fig.5: when connecting the ESP-01 to
a Micromite you still need a 5V-3.3V
LDO regulator. However, no level
translation is needed so the data pins
can be connected directly.
text commands, using it to add WiFi
capabilities to your microcontroller
project is relatively easy. All your Arduino sketch or MMBasic program
needs to do is set up the ESP8266 chip
using the appropriate AT commands,
and then respond to the data it gets
back from the ESP8266.
If this sounds a bit daunting, you can
find a list of all the commands here:
siliconchip.com.au/link/aaj7
If you want to use the ESP-01 module with a Micromite, you’ll get a lot
of help and guidance by studying a
program that Micromite guru Geoff
Graham wrote to accompany his article published in the December 2014
issue of Silicon Chip. The program is
called “WEBServer.bas” and can be
downloaded for free from siliconchip.
com.au/Shop/6/2890
You’ll also find that Geoff Graham’s
article in the December 2014 issue
has a listing of the main AT commands needed to communicate with
the ESP-01/ESP8266 (page 33, www.
siliconchip.com.au/Article/8194).
The ESP1SH shield makes most
of the connections between the ESP01 and the Arduino Mega, when you
plug it in.
The only additional connections
you need to make are between the
level translated TX and RX lines of
the ESP-01 (the uppermost and lowermost rows of pins on the shield’s 8x3
programming header) and the IO19/
RX1 and IO18/TX1 pins of the Ar-
duino Mega. As shown in the photo
below and in Fig.4, these added connections are made by short male-tofemale jumper leads.
Just remember to remove the
jumper shunts which come with the
ESP1SH shield, because these can
only be used to connect the ESP-01’s
TX and RX lines to the Mega’s IO0/
RX0 and IO1/TX0 hardware UART (or
to pins IO2-IO7 for using a software
serial port).
The jumper lead from one of the uppermost TX pins of the shield’s 8x3
header needs to be connected to the
Mega’s IO19/RX1 socket (blue lead in
Fig.4), while the lowermost RX pins
on the header should be connected to
the Mega’s IO18/TX1 socket (red lead
in Fig.4). If you get these two connections swapped, your Mega won’t be
able to communicate with the ESP01 module.
Programming the Mega for WiFi
communication via the ESP-01 is fairly
easy. You’ll find quite a few Arduino
sketches on the web which illustrate
how you can use the ESP8266, and
there’s also a WiFi Library available on
the main Arduino website (see www.
arduino.cc/en/Reference/Libraries).
To get you started, I’ve adapted
a simple pass-through sketch that I
found on one of the websites so that
it’s capable of running straight away
on the Mega/ESP1SH/ESP-01 setup.
The sketch makes the Mega behave
as a relay station or mirror between
All that’s needed extra when
using the Freetronics ESP1SH is
two jumper leads to connect the
transmit and receive lines.
www.freetronics.com.au/products/
esp-01-wifi-module-shield
With an Arduino Mega
As mentioned earlier, the easiest
Arduino to connect with the ESP-01
module is the Mega. It’s especially
easy if you use a WiFi shield like the
Freetronics ESP1SH to interface between the two, as shown in the adjacent photo.
siliconchip.com.au
Celebrating 30 Years
April 2018 81
ing with the Mega and ESP8266 at
115,200 baud (bps).
Why not try programming the ESP01 WiFi module yourself?
// Sample program from Fig.6.
void setup() {
Serial.begin(115200);
Serial1.begin(115200);
}
void loop() {
if (Serial.available())
Serial1.write(Serial.read());
if (Serial1.available())
Serial.write(Serial1.read());
}
Loading your own code onto
the ESP8266
Fig.6: the sample serial passthrough program running on an Arduino Mega.
This program merely repeats data to and from the ESP-01 module.
your computer and the ESP-01 and
its ESP8266.
So any AT commands sent from your
computer via the Arduino IDE’s Serial Monitor utility are relayed to the
ESP8266, and any responses from the
ESP8266 are relayed back to the IDE’s
Serial Monitor. This makes it easy to
try sending various AT commands to
the ESP-01 and to see its responses.
The sketch is listed at the end of this
section and you can also download it
from the Silicon Chip website.
The screen grab shown in Fig.6
shows how this works. The lines underlined in red are those with the
AT commands sent to the ESP-01/
ESP8266, while those without any underlining show the responses coming
back from it. The first AT command
is basically just an enquiry to see if
the ESP8266 is awake, with it returning OK if it is.
Similarly, the command AT+GMR
resets the ESP8266 and also gets it to
respond with information concerning
its firmware.
Then the command AT+CWMODE=1
directs the ESP8266 to assume WiFi
client mode, as opposed to access
point mode (mode 2) or client/access
point mode (mode 3).
The additional command shown
in Fig.6 is AT+CWLAP which asks
the ESP8266 to list any WiFi access
points currently available within its
range. Of the three lines you can see
in Fig.6, the last line corresponds to
my office network router, while the
other two are routers or peripherals
in nearby homes.
The other point to note from Fig.6
is that the Arduino Mega I was using
at the time had been allocated to virtual COM port 20 (top left), while the
IDE Serial Monitor was communicat-
The WeMos D1 R2, which is based around the ESP8266,
was used in the Water Tank Level Meter project (Feb 18).
82
Silicon Chip
If you do this, you will lose the AT
command set capabilities, since these
are provided by the default code loaded into the ESP8266 processor. But it
does allow the ESP-01 to become an
independent module without the need
for many external components.
The best demonstration of this is in
our NTP Clock project article on page
58, where we turned an ESP-01 into
a device which pretends to be a GPS
module, supplying NMEA data from
its serial port and a 1pps signal but it
actually gets the time, date and location data from NTP and location servers on the internet. This allows you
to use a GPS-synchronised clock in
a location where a GPS signal is not
available.
So we won’t go into great detail
about how to program the ESP8266
yourself here, as you can refer to that
article on page 60 and examine its
source code (which can be downloaded from the Silicon Chip website)
to see how it works.
SC
Links for using the ESP-01/ESP8266:
https://espressif.com
www.siliconchip.com.au/link/aaj6
https://forum.arduino.cc/index.php?board=11.0
http://bbs.espressif.com
www.electrodragon.com/w/Wi07c
www.siliconchip.com.au/link/aaj7
www.sparkfun.com/products/13678
https://en.wikipedia.org/wiki/ESP8266
www. siliconchip.com.au/link/aaj8
https://github.com/espressif
https://github.com/esp8266/Arduino
https://github.com/tttapa/ESP8266
https://github.com/acrobotic/Ai_Docs
https://github.com/espressif/esp8266_mp3_decoder/
Celebrating 30 Years
siliconchip.com.au
siliconchip.com.au
Celebrating 30 Years
April 2018 83
Vintage Radio
By Ian Batty
Astor M2 Cry-baby
a radio, intercom and baby monitor all in one
You might think that baby monitors are a fairly recent innovation but
this battery-powered solid-state mantel radio from Astor incorporated
an intercom and baby monitor in a design from 1962 – 56 years ago!
This mantel radio looks similar to
the Astor M5 and M6 mantel sets that
I wrote up in the September 2016
issue (www.siliconchip.com.au/
Article/10149). Those mains-powered
sets had Class-A audio output stages.
At the time, I’d pondered the design
brief but supposed that mains sets
could easily support the power drain
penalty of Class-A.
I did wonder about a battery version
and assumed it would need to use the
more complex (and thus more costly)
Class-B design for battery economy.
The 1962 M2 does indeed do this. The
Class-B output stage gives an overall
drain of around 10mA, meaning that
the original Eveready 276-P carbonzinc battery would last for some 150
hours of use.
84
Silicon Chip
As well as the M5/M6’s radio function, a remote speaker connected to the
M2 allows baby monitoring, playing radio programs at the remote speaker, or
conventional “half-duplex” intercom
operation. Being able to use the extension speaker for the radio program
would be a useful feature even today.
We usually think of loudspeakers
as output transducers but (like many
electromechanical devices), we can
capitalise on their reciprocal nature
and use them as microphones. This
is what the M2 does with its remote
speaker, using it either as a speaker or
with a suitable step-up transformer, as
a microphone.
I was offered this set for review by a
fellow member of the Historical Radio
Society of Australia (HRSA), whom I
Celebrating 30 Years
have credited at the end of this article.
Appearance and controls
The cabinet of the Astor M2 is very
similar to that of the previously-reviewed M5 and has the same handspan dial for tuning and a 4-inch
speaker on the left-hand side of the
front panel.
The set retailed for £37.16s with the
case and external speaker presented in
a variety of different colours such as
cherry red, yellow, brown etc.
The major difference is a 5-position
function switch on the right-hand side
of the panel, while the volume controlcum-power switch is on the left-hand
side. The monitor speaker is in a black
circular housing with no styling similarity to the radio.
siliconchip.com.au
Fig.1: the complete circuit for the Astor Cry-baby. Note the complex wiring for the 4-pole function switch. The
loudspeaker was connected via a step-up transformer (#74) when it was being used as a baby monitor.
Position 1 of the function switch
simply parallels the monitor speaker
with the set’s internal speaker, so it
operates as an extension to play the
received program. Position 2 switches
off the monitor speaker.
Position 3 adds remote (baby) monitoring to the radio function but with
the remote input at full gain while the
radio program is subject to the volume
control setting. This would be ideal
for baby monitoring; you’d be alerted
to anything happening in the nursery
while listening to the radio or you
could turn the radio down while still
monitoring your infant.
Position 4 is a simple intercom
working from remote speaker to the
set while position 5 reverses the conversation, going from set to monitor.
Just as an aside, if you have one of
these sets, make sure that the remote
speaker is reasonably remote before
switching to position 3: insufficient
separation will result in very loud
acoustic feedback.
siliconchip.com.au
Construction
Like the Astor M5 & M6, the M2 uses
a single-sided phenolic PCB mounted
behind the plastic front panel and anchored by the volume pot and function
switch’s shafts, and by two screws;
there is no metal chassis.
The only unusual component is the
3.5mm external speaker jack mounted
in the rear of the case, and connected to
pins on the circuit board by fly leads.
Like the M5/6, tuning knob removal requires gently prising off the gold
dress cap in the centre of the dial, undoing the three small screws and securing ring that hold the tuning knob
on, then (for circuit board removal),
undoing two screws in the tuning boss
and sliding it off the gang’s shaft.
The set provides for external Aerial and Earth connections to improve
reception in fringe areas. As with the
M5 model, these “hide” under the set
and connect via the two bottom case
screws.
While such connections are always
Celebrating 30 Years
welcome, you’d need to be a long way
from the station before this sensitive
set needed external assistance.
Fig.1 shows the full circuit and as
with other Astor radios, each component has a simple “hash” number. All
the transistors are PNP germanium
types while the two diodes are also
germanium.
However, the battery supply is unconventional, with positive Earth and
the circuit has been drawn to show
conventional flow from positive to
negative, “up the page”.
A comparison with the circuit of
the Astor M5 featured in the September 2016 issue shows that it is quite
similar to that of the M2 model, with
the exception of the M2’s Class-B audio output amplifier; more correctly
termed “Class-AB” because the output transistors do have a small bias to
provide quiescent current.
The self-oscillating converter #78, a
2N412, uses collector-emitter feedback
with the incoming RF signal applied
April 2018 85
The large rotary switch for the function control is on the left hand side of the PCB. The two output transistors are fitted
with flag heatsinks which have been soldered to the frame of the output transformer. This photo was taken after replacing
numerous electrolytic capacitors.
to the base of the converter (from the
ferrite antenna via 10nF capacitor #3).
Like almost all such converters, no
AGC is applied to this stage.
The tuning gang uses a cut plate oscillator section, so there is no padder
capacitor.
The converter feeds through oscillator coil #70’s primary to the primary
of first IF transformer #71. Its tuned,
tapped primary couples to the untuned, untapped secondary.
The first IF amplifier (#80), a 2N410,
gets its bias via a 150kW resistor (#47)
connected to the +9V supply. It is
neutralised via an 8.2pF capacitor.
Its output goes to the second IF transformer’s tuned, tapped primary and
its untuned, untapped secondary
86
Silicon Chip
feeds the second IF amplifier, another
2N410 (#81).
Astor recommended that both IF
transistors are picked from the same
gain group.
The 1st IF amplifier has AGC applied from the 1N295 detector diode (#82) via a 4.7kW resistor (#46).
This directly controls the amplifier’s
gain, and brings AGC extension diode
#79, another 1N295, into action with
stronger signals.
It’s the conventional “Mullard” design, allowing the set to respond to
varying signal strengths with a nearconstant output level.
The 2nd IF amplifier is neutralised
via a 27pF capacitor (#15). Its value is
some three times that of #7, necessary
Celebrating 30 Years
since #15 is fed from the IFT’s secondary rather than the primary as with the
1st IF amplifier’s #7.
As well as providing the AGC signal,
diode #82 provides the demodulated
audio signal which is filtered by two
10nF capacitors (#18 and #19) and a
220W resistor (#48).
The recovered audio signal is fed
to the 10kW volume control via a 2µF
capacitor and a section of the 4-pole
function switch wiring when set the
“radio” position.
Audio stages
The audio section of the M2 radio
comprises three stages, with the first
two 2N406 audio transistors, #83 and
#84, operating in a high-gain, direct-
siliconchip.com.au
The Aegis branded extension speaker is clearly not the original Astor-branded speaker which was made by Rola. It
was supplied with 23m of 2-core flex and it could be used as a baby monitor, extension speaker or as an intercom.
coupled configuration and with DC
feedback applied from #84’s emitter
to #83’s base, with the actual voltage picked off from the 330W/680W
(#56/#57) voltage divider. Some local
negative feedback is applied across
driver transistor #84 via 100kW resistor #59.
Both the emitter circuits are bypassed for audio, with transistor #83
having a 10W resistor (#54) allowing
overall AC feedback to be applied
from the speaker output via a 15kW
resistor (#66).
Transistor #84 feeds the primary of
driver transformer #75 and its centretapped secondary feeds the two output
transistors, #85 and #86. These two
OC74s drive the output transformer
in push-pull fashion.
They are fitted with flag heatsinks
soldered to the frame of the output
transformer, giving a large thermal
mass to help keep transistor junctions
at a constant temperature.
The bias for the output transistors
is derived from a voltage divider comprising resistors #62 (10kW) and #65
(560W) combined with a negative temperature coefficient (NTC) thermistor
(#64, 220W) to give temperature compensation.
It’s the usual arrangement whereby
the thermistor reduces bias at higher
temperatures to prevent excessive current in the output stage.
This bias network cannot compensate for falling battery voltage and nor
can the bias be optimised for individual
siliconchip.com.au
transistors. This is borne out by the
small amount of crossover distortion
present even at full battery voltage.
Local feedback is provided by 10nF
capacitors #28 and #29 from the collectors to the bases of the output transistors, with further treble cut provided
by 10nF capacitor #30.
Monitoring and intercom
Position 3 of the function switch
sees a 470W resistor (#49) in series
between the volume pot’s wiper and
audio input, with #88/b also connecting a 470W resistor (#45) to the audio
input via the 2µF capacitor to the base
of transistor #83.
This allows audio from the external
speaker (operating as a microphone,
stepped up by 2kW:15W matching
transformer #74) to be passively mixed
with the audio coming via the volume
control.
Thus, while it’s possible to adjust
the level of the radio program, audio
from the remote speaker is conveyed
at maximum gain.
Position 4 of the function switch removes the radio program but connects
to the matching transformer’s secondary and conveys its signal to the volume control, while #88/b shorts out
resistor #49 to deliver the full signal
to the audio amplifier. The set is now
a conventional intercom in the “listen” position.
Signal direction, from the external
speaker to the internal speaker, is controlled by #88/c conveying the ampliCelebrating 30 Years
fier’s output to the internal speaker,
and #88/d connecting the external
speaker to the input of matching transformer #74.
Position 5 selects “talk” operation.
Switch #88/c connects the internal
speaker to matching transformer #74
to allow the internal speaker to act as a
microphone, while #88/d sends audio
output to the external speaker.
Fixing it up
As presented to me, the M2 needed
only a light clean and polish to make
it sparkle but electrically it was dead.
However, my Local Oscillator test
brought out that “swishing” sound
from my bench radio, so it looked like
an audio problem.
Homing in on and replacing electrolytic coupling capacitors #20 and
#23 brought immediate results. For
good measure, I replaced bypass caps
#9, #26 and #31, and got improved
performance with emitter bypasses
#25 and #27.
Poor quality manufacture? Well, the
set had probably been sitting unused
for some decades and it’s too much
to expect the chemically-formed dielectric to persist for so long with no
refreshing.
I did try reforming the capacitors but
with no success. I’m also pessimistic
about the long-term stability of such
old components anyway.
If you're having difficulty getting
axial-lead electrolytic capacitors,
both low-voltage (transistor radios,
April 2018 87
valve cathode bypasses) and highvoltage (valve power supplies) types
are available from local surplus stores
and online.
A tip though: chatting with one local store revealed that axial electrolytics are getting harder to find. I found a
range of axial electrolytics at Rockby
Electronics in Melbourne. You might
like to check out their online catalog.
How good is it?
The Astor M2 is right up there with
the best of the alloyed-junction germanium designs. Its sensitivity is aided
by the high-gain, three-stage audio
section.
For 50mW output, it needed around
45µV/m at 600kHz and 35µV/m at
1400kHz, but at signal-to-noise (S/N)
ratios of only -7dB and -10dB, respectively. For the more usual S/N value
of -20dB, the equivalent signals were
90µV/m at 600kHz and 65µV/m at
1400kHz.
At the antenna terminal, it needed
only 8.5µV at 600kHz and 12µV at
1400kHz, for S/N ratios of -9dB and
-10dB. For the usual -20dB ratios:
16µV and 21µV, respectively.
IF bandwidth is ±1.5kHz at -3dB
down and ±24kHz at -60dB down.
AGC allows some 6dB rise in audio
for a 50dB signal increase. I did finally
get it to overload at around 200mV/m;
an exceptional performance.
Audio response from antenna to
speaker was 50Hz to 1500Hz, with a
peak at about 80Hz. From volume control to speaker, it’s 65Hz to 7800Hz.
From the monitoring speaker input,
it’s around 135Hz to 8500Hz, with a
7dB peak at 5kHz. This may be due
to input transformer resonance but it
would help compensate for the monitor speaker’s expected weak high-frequency response.
At 50mW, audio distortion was commendably low, at only 0.8% but it rose
to 1.5% at 10mW, with discernible
crossover distortion. This confirms
the limitations of non-adjustable bias
circuits.
It went into clipping at 400mW,
with 10% distortion at 500mW. At a
low battery voltage of 4.5V, it clips at
80mW, with around 5% THD at 50mW,
noticeably crossover distortion.
As a radio, it’s great. And for its
special features, it’s equally so. The
remote speaker input gives 50mW
out with only 250µV of audio input
at full volume.
88
Silicon Chip
Women’s Weekly, 18th July, 1962: https://trove.nla.gov.au/aww/read/222697
This is certainly adequate to pick up
sounds from the monitor speaker, even
with “house-length” runs of common
speaker cable. In fact, the radio was
supplied with 75 feet (23m) of 2-core
flex for this purpose.
Whether used as a portable radio,
nursery monitor or as an ordinary intercom, the audio section’s high sensitivity and generous audio output mean
that it easily fills the bill.
Would I Buy One?
That’s tempting but I’d like to get
an M2 with the original Astor speaker. While the substitute Aegis monitor works just fine, there’s no substitute for the genuine article (actually
made by Rola).
Celebrating 30 Years
If you happen to have either the
complete radio-and-speaker kit that
you’d like to move on, or even just the
speaker, please drop Graham or me a
line via Silicon Chip ([02]9939-3295
or silicon<at>siliconchip.com.au).
Acknowledgement:
Special thanks to Associate Professor (retired) Graham Parslow of the
HRSA, for this interesting example of
fine Australian engineering and manufacture.
Further reading
You will find the circuit and service info on Kevin Chant’s excellent site at www.kevinchant.com/
uploads/7/1/0/8/7108231/m2a.pdf SC
siliconchip.com.au
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. Send your email to silicon<at>siliconchip.com.au
Is WiFi Water Tank
Level Meter suitable for
drinking water?
Can you confirm if the water level/
pressure sensor that you sell for the
WiFi Water Tank Level Meter (Cat
SC4283) is safe to be used in tanks for
drinking water? My understanding is
that it needs to be “Food Grade” to
be suitable. (D. B., Glenn Forest, WA)
• There is no indication in any of the
specifications supplied to us that the
sensors are food grade.
The sensor housing is made of stainless steel but we don’t know what
kind of plastic insulation is used on
the wire or whether there may be any
potentially toxic materials inside the
sensor housing. The sensors are most
suitable for rainwater or “grey” water,
used for watering plants, flushing toilets and so on.
TV channel
interference at night
I have a really perplexing problem
regarding digital TV reception, specifically the stations on 219.500MHz
(Network Ten). During daylight hours,
all networks are at 100% strength and
quality.
Come night, say from 7:30pm, all
stations on this frequency break up,
pixelate and are then, for want of a
better word, gone. Signal strength
still reads 100% but the bit error rate
is maximum. That results in no picture or sound.
Two networks 7MHz either side of
219.500MHz show no sign of any problems (Nine and ABC). On talkback radio this weekend, I heard one of those
"techie" guys explain that the new
LED globes can interfere with digital
TV reception.
Have you heard of this problem? We
are so frustrated that we now have a
VHF-only antenna in the hope that it
may be a quick fix. Unfortunately, it
didn’t help. (D. McC., Allawah, NSW)
• We would be surprised if any LED
lamps would cause interference at
siliconchip.com.au
those high frequencies. The problem
is more likely to be related to some
local source which is more active at
night, perhaps related to internet use
from the NBN or ADSL.
Do any of your neighbours have the
same problem? If not, the source may
in your own household. Is a family
member always on the ‘net at night?
If you can carefully follow the adjustment procedure, you should be
able to receive the bottom end of the
band. We were able to pick up the
Sydney ABC stations at 702kHz and
576kHz with our prototype.
Trouble aligning
Super-7 AM Radio
In regards to the January 2013 "Champion" amplifier (www.siliconchip.
com.au/Article/1301). In the Parts List
on page 26, some of the capacitors are
specified as 100nF MMC.
What does MMC refer to? I have
not seen it referred to in the Jaycar,
Altronics, element14 or RS catalogs.
I do see MKT, tantalum, monolithic,
polyester and ceramic capacitors. Are
any of these equivalent to MMC? (A.
P., Manapouri, NZ)
• "MMC" stands for Monolithic Multilayer Ceramic. It is now an outdated
term and we are trying to avoid using
it. You still see it occasionally on part
supplier websites and elsewhere.
"Monolithic" describes one type of
multi-layer ceramic construction. It
is not really relevant to most applications. As a result, you now mainly
see capacitors described as "multilayer ceramic", sometimes abbreviated to MLC or MLCC. They are basically equivalent to monolithic/MMC
capacitors.
I have just built the Super-7 AM
Radio (November & December 2017;
siliconchip.com.au/Series/321) and
am having trouble getting it working
properly.
The stations are too far towards the
high-frequency end of the dial and
when I adjust the oscillator coil to
correct this, they disappear altogether.
I really should have a signal generator and oscilloscope at hand but managed without them when I constructed
the RTV&H Transporta 7 in 1964 (it
still works, by the way).
During my deliberations, I looked at
Jaycar's data for the ferrite aerial coil
and the tuning condenser. The aerial
coil inductance is stated as 200µH and
the tuner's aerial gang capacitance as
141.6pF, although Jaycar advertises it
as 160pF. My calculation of the aerial
tuned circuit resonant frequency is
890kHz with the tuner at 160pF and
946kHz at 141.6pF.
Given that the frequency is supposed to range down to 530kHz or
thereabouts, I wonder whether there
is a basic design problem or whether
I have missed something. Your advice
would be much appreciated. (R. H.,
Bronte, NSW)
• The ferrite rod, coil and tuning capacitor are designed to suit the AM
broadcast band. The inductance can
be changed markedly by moving the
coil on the ferrite rod.
Also, the tuning gang capacitance is
affected by the trimmer at the back of
the capacitor gang. Getting these correct for alignment can be a slow procedure if these are initially way off value.
Celebrating 30 Years
Continuing confusion
over “MMC” capacitors
Sourcing a transformer
for the SC200
An EPE reader is having trouble
finding a suitable mains transformer
for the SC200 Amplifier module (January-March 2017; siliconchip.com.au/
Series/308).
We can't find a 40-0-40 + 15-0-15
transformer anywhere. The dual secondaries are the problem. Jaycar and
Altronics don’t have them. Do you
have an alternative source? Also, what
is the part number for ferrite bead FB1?
(M. P., Wimborne, UK)
• The transformer used originally
was the Altronics MC5540 which has
April 2018 89
now been discontinued, along with
the amplifier kits which included that
transformer.
The easiest solution is to use two
transformers: one 300VA 40-0-40
transformer and a 20-30VA 15-0-15
transformer like Jaycar MT2086 or
Altronics M4915B. The primaries of
the two transformers should be wired
in parallel.
Arguably this is superior to a single
transformer since the 300VA transformer is then tasked with only supplying the power amplifiers, so it will
be able to supply slightly more peak
current. It should also make chassis
layout and wiring easier.
The ferrite bead type isn't critical;
Laird HZ1206E152R-10 would be a
good choice.
Question about unused
op amp
Regarding the WiFi Water Tank Level Meter circuit on page 22 of the February 2018 issue (siliconchip.com.au/
Article/10963), I don’t understand the
function of the IC1a voltage follower.
You don't appear to discuss IC1a in the
text. Thanks for such a great magazine
with fantastic project presentation. (S.
E., Scullin, ACT)
• IC1a is the unused half of the dual
op amp. Only IC1b is required but IC1a
needs to have its inputs connected
to voltage levels within its common
mode range. Making it a voltage follower is a simple way to achieve this.
Since it's an LM358, we could
have connected pin 3 to pin 4 instead
(ground) but some op amps will misbehave with the inputs tied to ground
so this is a safer general configuration
for unused op amp stages.
CDI wanted for Honda
CBR250
I am looking for information about
some of your Capacitor Discharge Ignition designs. I have a 4-cylinder Honda
CBR250 motorcycle running two pulser
coils that are mounted about 30° apart.
I am wondering if you have a kit
that would work in my application. I’d
like to be able to program the advance
curve; the original CDI only references
RPM for its mapping. (J. L., via email)
• We have published a High-Energy Multi-spark CDI design (December 2014 & January 2015; siliconchip.
com.au/Series/279), a Programmable
Ignition system (March-June 2007;
siliconchip.com.au/Series/56), plus
a standard High-energy Ignition system (November-December 2012;
siliconchip.com.au/Series/18).
For irregularly spaced triggers such
as in your engine, it would require at
least two ignition systems, one for the
first trigger and another for the trigger
30° apart. The size of these ignitions
may not suit a motorcycle, especially
if you include the programmable ignition ahead of the CDI unit.
Resistors for Theremin
and kit availability
I am building the Theremin as de-
Could the RapidBrake have been designed without relays?
I have three questions:
Could the RapidBrake (JulyAugust 2017; siliconchip.com.au/
Series/314) have been designed as an
OBD-II dongle and as such not need
relays? I am guessing the brake lights
are accessible via the OBD-II bus.
Secondly, regarding your Arduino
Data Logger project (August-September 2017; siliconchip.com.au/
Series/316), I am interested in building it to store weather data but how
can I log rain (tipping bucket) and
wind speed/direction?
Would I be best looking at a different design or can yours be modified to do it?
Lastly, with the "El Cheapo"
modules you have been informing us about, have you considered
the BME280 or BME680 barometric
pressure modules?
They are remarkable for their prices and easy to use with an Arduino.
(P. R., Bribie Island, Qld)
• While it’s probably possible to
monitor brake light status on some
vehicles via the OBD-II bus, we are
not aware of any (standard) way to
activate the brake lights over that
bus.
90
Silicon Chip
Indeed, on many vehicles, even
those new enough to have an OBDII connector, the brake lights are still
activated by a physical switch in the
pedal mechanism.
Even if some modern vehicles do
have the brake lights under control
of the body computer and you could
somehow command it to activate
them via the OBD-II interface, that
would rule out its use on any vehicles lacking this capability and all
vehicles that pre-date OBD-II.
It became mandatory in 20052007, depending on vehicle type,
although some vehicles dating back
to the late 1990s have it.
Since our Data Logger is based on
the Arduino and the source code can
be downloaded, there's nothing to
stop constructors from adding the
ability to measure rainfall, wind
speed and direction.
We provided sample instructions
on how to interface extra sensors;
it wouldn't be exactly the same but
that should serve as a general guide
to the steps required.
The difficulty with rainfall measurement using a tipping bucket is
that to save power, our Data Logger
Celebrating 30 Years
puts the micro into sleep mode much
of the time and thus it could miss
pulses during this period.
You can arrange for the micro to
wake up when the level changes
on a specific pin and this is what
we would be tempted to do, as you
could keep the power savings without missing these pulses, which
will not normally occur frequently
anyway.
For wind speed and direction, it
really depends on the type of wind
speed sensor you are using.
Wind speed will probably be based
on counting pulses over a given
period and so the above also applies,
except that you will also need to
divide the number of pulses by the
timespan they are recorded over to
calculate the speed.
Determination of wind direction
may require a few digital inputs or
one analog input. In short, it should
be possible to add these features but
may require some coding skill.
Finally, the BME680 looks like a
good chip but the cheapest module
we can find is around $50 which
doesn’t exactly fit into the “El
Cheapo” category.
siliconchip.com.au
scribed in January 2018 issue of Silicon Chip magazine (siliconchip.com.
au/Article/10931).
My question is: are 5% tolerance resistors acceptable for this project? The
reason for this question is that I have
already purchased and fitted 5% resistors before I realised that 1% resistors were specified. (P. I., Alawa, NT)
• Yes, 5% resistors should work in
this project. By the way, we believe
that Jaycar will be releasing a kit for
this Theremin fairly soon.
Directionality in audio
cables is nonsense
Recently, whilst dining with a friend
of mine, we got to discussing audio
equipment and the difference in audio cables. He explained to me that
the high-quality audio cables he purchased some time ago become noticeably better over time, due to burn-in,
or break-in. He would not accept that
most of the information he has read is
far-fetched sales blurb.
I mentioned the importance of such
things as shielding and cable losses
etc, but I was not a believer in the
break-in theory. He tried to convince
me that it is true and he read it on the
experts' websites, such as Nordost –
see the FAQs at www.nordost.com/
faqs.php
In the FAQ "How can cables be directional?" They explain that during
the break-in period cables acquire directionality – "small impurities in the
conductor act as diodes allowing signal flow to be better in one direction
over time. This effect is also called
quantum tunneling,".
Other related FAQs are also an interesting read. Would you care to share
an educated opinion on this mumbojumbo? (T. C., via email)
• Sadly, this fraudulent nonsense is
still being pushed by marketing companies. As you say, it is mumbo-jumbo.
Cables are not directional, nor is
there any way they could be made
directional without introducing some
form of non-linearity. After all, au-
Testing relays
Have you published a project or
kit to test relays with? Or is there
a schematic diagram of one that I
could make? (B. V., via email)
• We have not published a relay
tester. It is not really practical to design a tester due to the range of relay
types available.
Standard relays are relatively easy
to test. You will need a power supply to drive the relay coil with the
correct voltage. Some relays require
12V DC for the coil, while others can
be 5V DC.
Mains operated relays require a
230VAC supply to the coil in order
to switch contacts. Take care if testing these as contact with the mains
voltage can be lethal.
Relays will operate over a wide
range of voltages below the rated coil
voltage. See the data for the relay.
Specifications are usually given
for the “must operate” (ie, minimum
voltage at which the relay is guaranteed to switch on) and the “holding voltage” (voltage below which
the relay may switch off again) for
the coil.
To test the coil, apply power to it
and check that it draws current. You
siliconchip.com.au
may hear a click as the relay draws
the armature to its solenoid.
The relay contacts can be checked
using a multimeter. The normally
open (NO) contacts should show
high resistance (above 1MW) between that contact and the common
(COM) when the relay coil is not
powered but will be low resistance
(<1W) when closed as power is applied to the relay coil.
For normally closed (NC) contacts, it is the reverse. There will be a
low resistance reading when the coil
is not powered and high resistance
when the coil is energised.
Relay contacts may become pitted
with use and so contact testing can
be more effective by applying current through the contacts to check
contact resistance under load.
Latching relays are different and
the data for the particular relay will
need to be checked for setting and
resetting the contacts.
Some have one coil, where the applied polarity is reversed to switch
the relay on and off, while other
relays have two coils for operation, one to switch on and one to
switch off.
Celebrating 30 Years
dio signals are AC, so current flow
in the cable is constantly changing
direction.
Therefore, if such a non-linearity
was present, it would cause audible
distortion. Small impurities in copper or other conductors do not act as
diodes. If they did, it would possible
to measure the diode effect.
In fact, it is quite simple to measure
if there is any difference in conductance (the reciprocal of resistance) in a
cable in both directions. Just use your
multimeter (set to ohms) and measure the resistance in both directions
of the cable. Apart from tiny variations in contact resistance between
repeated measurements, there will be
no difference.
Oh, and if the proponents of this
effect try to state that the directionality is also present in the dielectric of
shielded cables, that is also nonsense
and can be refuted by measurements
with AC signals.
And nor is there any effect if a polarising voltage is applied to the cable.
In any case, external audio cables used
in audio systems are not polarised.
That brings up another point. Contact resistance between dissimilar metals can cause non-linearity and can
be a source of distortion. This applies
particularly to cheap spring-loaded
terminals on the back of some audio
amplifiers and loudspeakers. Ideally,
they should be hefty brass screw connections with gold flashing.
And can cables get better over time
and do they need any burn-in? Again,
this is nonsense. No components improve over time – they all deteriorate
and eventually fail, even if it happens
after decades of use. Always remember: “Entropy is increasing!”
It is true that the cone resonance of
woofer loudspeakers can slightly reduce after an initial period of use, say
a couple of hours. But after that, there
is no improvement.
Consider that the reduction in cone
resonance is due to an increase in compliance of the cone suspension, ie, the
roll surround and the central spider
which precisely locates the voice coil
over the magnet's pole piece.
In other words, the suspension becomes looser. Is this not an initial deterioration in stiffness of the suspension? It is.
We should also state that some RCA
cables are cheap-jack, with flimsy connectors and it is better to purchase caApril 2018 91
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SPECIALISED COMPONENTS, HARD-TO-GET BITS, ETC
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SBK-71K coil former pack (two required)
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1nF 1% MKP capacitor, 5mm lead spacing
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(MAR 17)
Hard to get parts: DRV8871 IC, SMD 1µF capacitor and 100kW potentiometer with detent
$12.50
ULTRA LOW VOLTAGE LED FLASHER (CAT SC4125)
(FEB 17)
SC200 AMPLIFIER MODULE (CAT SC4140)
(JAN 17)
60V 40A DC MOTOR SPEED CONTROLLER (CAT SC4142)
(JAN 17)
kit including PCB and all SMD parts, LDR and blue LED
hard-to-get parts: Q8-Q16, D2-D4, 150pF/250V capacitor and five SMD resistors
hard-to-get parts: IC2, Q1, Q2 and D1
$12.50
$35.00
$35.00
VARIOUS MODULES
ESP-01 WiFi Module (El Cheapo Modules, Part 15, APR18)
$5.00
WiFi Antennas with U.FL/IPX connectors (Water Tank Level Meter with WiFi, FEB18):
5dBi – $12.50 ~ 2dBi (omnidirectional) – $10.00
NRF24L01+PA+NA transceiver with SNA connector and antenna (El Cheapo 12, JAN18)
$5.00
WeMos D1 Arduino-compatible boards with WiFi (SEPT17, FEB18):
ThingSpeak data logger – $10.00 ~ WiFi Tank Level Meter (ext. antenna socket) – $15.00
Geeetech Arduino MP3 shield (Arduino Music Player/Recorder, VS1053, JUL17)
$20.00
MAX7219 LED controller boards (El Cheapo Modules, Part 7, JUN17):
8x8 red SMD/DIP matrix display – $5.00 ~ red 8-digit 7-segment display – $7.50
AD9833 DDS module (with gain control) (for Micromite DDS, APR17)
$25.00
AD9833 DDS module (no gain control) (El Cheapo Modules, Part 6, APR17)
$15.00
CP2102 USB-UART bridge
$5.00
microSD card adaptor (El Cheapo Modules, Part 3, JAN17)
$2.50
DS3231 real-time clock with mounting spacers and screws (El Cheapo, Part 1, OCT16)
$5.00
MICROMITE PLUS EXPLORE 100 COMPLETE KIT (no LCD panel)
(SEP 16)
(includes PCB, programmed micro and the hard-to-get bits including female headers, USB
and microSD sockets, crystal, etc but does not include the LCD panel) (Cat SC3834)
$69.90
MICROMITE LCD BACKPACK V1 COMPLETE KIT (CAT SC3321)
includes PCB, micro, 2.8-inch touchscreen and includes UB3 lid (clear, matte black
or translucent blue). Also specify what project the micro should be programmed for
(FEB 16)
$65.00
THESE ARE ONLY THE MOST RECENT MICROS AND SPECIALISED COMPONENTS. FOR THE FULL LIST, SEE www.siliconchip.com.au/shop
*All items subect to availability. Prices valid for month of magazine issue only. All prices in Australian dollars and include GST where applicable. # P&P prices are within Australia. O’seas? Please email for a quote
04/18
PRINTED CIRCUIT BOARDS
NOTE: The listings below are for the PCB ONLY. If you want a kit, check our store or contact the kit suppliers advertising in this
issue. For unusual projects where kits are not available, some have specialised components available – see the list opposite.
NOTE: Not all PCBs are shown here due to space limits but the Silicon Chip Online Shop has boards going back to 2001 and beyond.
For a complete list of available PCBs etc, go to siliconchip.com.au/shop/8 Prices are PCBs only, NOT COMPLETE KITS!
PRINTED CIRCUIT BOARD TO SUIT PROJECT:
PUBLISHED:
PCB CODE:
Price:
CLASSiC DAC MAIN PCB
APR 2013
01102131 $40.00
CLASSiC DAC FRONT & REAR PANEL PCBs
APR 2013
01102132/3 $30.00
GPS USB TIMEBASE
APR 2013
04104131 $15.00
LED LADYBIRD
APR 2013
08103131
$5.00
CLASSiC-D 12V to ±35V DC/DC CONVERTER
MAY 2013
11104131 $15.00
DO NOT DISTURB
MAY 2013
12104131 $10.00
LF/HF UP-CONVERTER
JUN 2013
07106131 $10.00
10-CHANNEL REMOTE CONTROL RECEIVER
JUN 2013
15106131 $15.00
IR-TO-455MHz UHF TRANSCEIVER
JUN 2013
15106132
$7.50
“LUMP IN COAX” PORTABLE MIXER
JUN 2013
01106131 $15.00
L’IL PULSER MKII TRAIN CONTROLLER
JULY 2013
09107131 $15.00
L’IL PULSER MKII FRONT & REAR PANELS
JULY 2013
09107132/3 $20.00/set
REVISED 10 CHANNEL REMOTE CONTROL RECEIVER
JULY 2013
15106133 $15.00
INFRARED TO UHF CONVERTER
JULY 2013
15107131
$5.00
UHF TO INFRARED CONVERTER
JULY 2013
15107132 $10.00
IPOD CHARGER
AUG 2013
14108131
$5.00
PC BIRDIES
AUG 2013
08104131 $10.00
RF DETECTOR PROBE FOR DMMs
AUG 2013
04107131 $10.00
BATTERY LIFESAVER
SEPT 2013
11108131
$5.00
SPEEDO CORRECTOR
SEPT 2013
05109131 $10.00
SiDRADIO (INTEGRATED SDR) Main PCB
OCT 2013
06109131 $35.00
SiDRADIO (INTEGRATED SDR) Front & Rear Panels
OCT 2013
06109132/3 $25.00/pr
TINY TIM AMPLIFIER (identical Headphone Amp [Sept11]) OCT 2013
01309111 $20.00
AUTO CAR HEADLIGHT CONTROLLER
OCT 2013
03111131 $10.00
GPS TRACKER
NOV 2013
05112131 $15.00
STEREO AUDIO DELAY/DSP
NOV 2013
01110131 $15.00
BELLBIRD
DEC 2013
08112131 $10.00
PORTAPAL-D MAIN BOARDS
DEC 2013
01111131-3 $35.00/set
(for CLASSiC-D Amp board and CLASSiC-D DC/DC Converter board refer above [Nov 2012/May 2013])
LED Party Strobe (also suits Hot Wire Cutter [Dec 2010])
JAN 2014
16101141
$7.50
Bass Extender Mk2
JAN 2014
01112131 $15.00
Li’l Pulser Mk2 Revised
JAN 2014
09107134 $15.00
10A 230VAC MOTOR SPEED CONTROLLER
FEB 2014
10102141 $12.50
NICAD/NIMH BURP CHARGER
MAR 2014
14103141 $15.00
RUBIDIUM FREQ. STANDARD BREAKOUT BOARD
APR 2014
04105141 $10.00
USB/RS232C ADAPTOR
APR 2014
07103141
$5.00
MAINS FAN SPEED CONTROLLER
MAY 2014
10104141 $10.00
RGB LED STRIP DRIVER
MAY 2014
16105141 $10.00
HYBRID BENCH SUPPLY
MAY 2014
18104141 $20.00
2-WAY PASSIVE LOUDSPEAKER CROSSOVER
JUN 2014
01205141 $20.00
TOUCHSCREEN AUDIO RECORDER
JUL 2014
01105141 $12.50
THRESHOLD VOLTAGE SWITCH
JUL 2014
99106141 $10.00
MICROMITE ASCII VIDEO TERMINAL
JUL 2014
24107141
$7.50
FREQUENCY COUNTER ADD-ON
JUL 2014
04105141a/b $15.00
TEMPMASTER MK3
AUG 2014
21108141 $15.00
44-PIN MICROMITE
AUG 2014
24108141
$5.00
OPTO-THEREMIN MAIN BOARD
SEP 2014
23108141 $15.00
OPTO-THEREMIN PROXIMITY SENSOR BOARD
SEP 2014
23108142
$5.00
ACTIVE DIFFERENTIAL PROBE BOARDS
SEP 2014
04107141/2 $10.00/set
MINI-D AMPLIFIER
SEP 2014
01110141
$5.00
COURTESY LIGHT DELAY
OCT 2014
05109141
$7.50
DIRECT INJECTION (D-I) BOX
OCT 2014
23109141
$5.00
DIGITAL EFFECTS UNIT
OCT 2014
01110131 $15.00
DUAL PHANTOM POWER SUPPLY
NOV 2014
18112141 $10.00
REMOTE MAINS TIMER
NOV 2014
19112141 $10.00
REMOTE MAINS TIMER PANEL/LID (BLUE)
NOV 2014
19112142 $15.00
ONE-CHIP AMPLIFIER
NOV 2014
01109141
$5.00
TDR DONGLE
DEC 2014
04112141
$5.00
MULTISPARK CDI FOR PERFORMANCE VEHICLES
DEC 2014
05112141 $10.00
CURRAWONG STEREO VALVE AMPLIFIER MAIN BOARD
DEC 2014
01111141 $50.00
CURRAWONG REMOTE CONTROL BOARD
DEC 2014
01111144
$5.00
CURRAWONG FRONT & REAR PANELS
DEC 2014
01111142/3 $30.00/set
CURRAWONG CLEAR ACRYLIC COVER
JAN 2015
SC2892
$25.00
ISOLATED HIGH VOLTAGE PROBE
JAN 2015
04108141 $10.00
SPARK ENERGY METER MAIN BOARD
FEB/MAR 2015
05101151 $10.00
SPARK ENERGY ZENER BOARD
FEB/MAR 2015
05101152 $10.00
SPARK ENERGY METER CALIBRATOR BOARD
FEB/MAR 2015
05101153
$5.00
APPLIANCE INSULATION TESTER
APR 2015
04103151 $10.00
APPLIANCE INSULATION TESTER FRONT PANEL
APR 2015
04103152 $10.00
LOW-FREQUENCY DISTORTION ANALYSER
APR 2015
04104151
$5.00
APPLIANCE EARTH LEAKAGE TESTER PCBs (2)
MAY 2015
04203151/2 $15.00
APPLIANCE EARTH LEAKAGE TESTER LID/PANEL
MAY 2015
04203153 $15.00
BALANCED INPUT ATTENUATOR MAIN PCB
MAY 2015
04105151 $15.00
BALANCED INPUT ATTENUATOR FRONT & REAR PANELS MAY 2015
04105152/3 $20.00
4-OUTPUT UNIVERSAL ADJUSTABLE REGULATOR
MAY 2015
18105151
$5.00
SIGNAL INJECTOR & TRACER
JUNE 2015
04106151
$7.50
PASSIVE RF PROBE
JUNE 2015
04106152
$2.50
SIGNAL INJECTOR & TRACER SHIELD
JUNE 2015
04106153
$5.00
BAD VIBES INFRASOUND SNOOPER
JUNE 2015
04104151
$5.00
CHAMPION + PRE-CHAMPION
JUNE 2015
01109121/2 $7.50
DRIVEWAY MONITOR TRANSMITTER PCB
JULY 2015
15105151 $10.00
DRIVEWAY MONITOR RECEIVER PCB
JULY 2015
15105152
$5.00
PRINTED CIRCUIT BOARD TO SUIT PROJECT:
PUBLISHED:
MINI USB SWITCHMODE REGULATOR
JULY 2015
VOLTAGE/RESISTANCE/CURRENT REFERENCE
AUG 2015
LED PARTY STROBE MK2
AUG 2015
ULTRA-LD MK4 200W AMPLIFIER MODULE
SEP 2015
9-CHANNEL REMOTE CONTROL RECEIVER
SEP 2015
MINI USB SWITCHMODE REGULATOR MK2
SEP 2015
2-WAY PASSIVE LOUDSPEAKER CROSSOVER
OCT 2015
ULTRA LD AMPLIFIER POWER SUPPLY
OCT 2015
ARDUINO USB ELECTROCARDIOGRAPH
OCT 2015
FINGERPRINT SCANNER – SET OF TWO PCBS
NOV 2015
LOUDSPEAKER PROTECTOR
NOV 2015
LED CLOCK
DEC 2015
SPEECH TIMER
DEC 2015
TURNTABLE STROBE
DEC 2015
CALIBRATED TURNTABLE STROBOSCOPE ETCHED DISC
DEC 2015
VALVE STEREO PREAMPLIFIER – PCB
JAN 2016
VALVE STEREO PREAMPLIFIER – CASE PARTS
JAN 2016
QUICKBRAKE BRAKE LIGHT SPEEDUP
JAN 2016
SOLAR MPPT CHARGER & LIGHTING CONTROLLER FEB/MAR 2016
MICROMITE LCD BACKPACK, 2.4-INCH VERSION
FEB/MAR 2016
MICROMITE LCD BACKPACK, 2.8-INCH VERSION
FEB/MAR 2016
BATTERY CELL BALANCER
MAR 2016
DELTA THROTTLE TIMER
MAR 2016
MICROWAVE LEAKAGE DETECTOR
APR 2016
FRIDGE/FREEZER ALARM
APR 2016
ARDUINO MULTIFUNCTION MEASUREMENT
APR 2016
PRECISION 50/60Hz TURNTABLE DRIVER
MAY 2016
RASPBERRY PI TEMP SENSOR EXPANSION
MAY 2016
100DB STEREO AUDIO LEVEL/VU METER
JUN 2016
HOTEL SAFE ALARM
JUN 2016
UNIVERSAL TEMPERATURE ALARM
JULY 2016
BROWNOUT PROTECTOR MK2
JULY 2016
8-DIGIT FREQUENCY METER
AUG 2016
APPLIANCE ENERGY METER
AUG 2016
MICROMITE PLUS EXPLORE 64
AUG 2016
CYCLIC PUMP/MAINS TIMER
SEPT 2016
MICROMITE PLUS EXPLORE 100 (4 layer)
SEPT 2016
AUTOMOTIVE FAULT DETECTOR
SEPT 2016
MOSQUITO LURE
OCT 2016
MICROPOWER LED FLASHER
OCT 2016
MINI MICROPOWER LED FLASHER
OCT 2016
50A BATTERY CHARGER CONTROLLER
NOV 2016
PASSIVE LINE TO PHONO INPUT CONVERTER
NOV 2016
MICROMITE PLUS LCD BACKPACK
NOV 2016
AUTOMOTIVE SENSOR MODIFIER
DEC 2016
TOUCHSCREEN VOLTAGE/CURRENT REFERENCE
DEC 2016
SC200 AMPLIFIER MODULE
JAN 2017
60V 40A DC MOTOR SPEED CON. CONTROL BOARD
JAN 2017
60V 40A DC MOTOR SPEED CON. MOSFET BOARD
JAN 2017
GPS SYNCHRONISED ANALOG CLOCK
FEB 2017
ULTRA LOW VOLTAGE LED FLASHER
FEB 2017
POOL LAP COUNTER
MAR 2017
STATIONMASTER TRAIN CONTROLLER
MAR 2017
EFUSE
APR 2017
SPRING REVERB
APR 2017
6GHz+ 1000:1 PRESCALER
MAY 2017
MICROBRIDGE
MAY 2017
MICROMITE LCD BACKPACK V2
MAY 2017
10-OCTAVE STEREO GRAPHIC EQUALISER PCB
JUN 2017
10-OCTAVE STEREO GRAPHIC EQUALISER FRONT PANEL JUN 2017
10-OCTAVE STEREO GRAPHIC EQUALISER CASE PIECES
JUN 2017
RAPIDBRAKE
JUL 2017
DELUXE EFUSE
AUG 2017
DELUXE EFUSE UB1 LID
AUG 2017
MAINS SUPPLY FOR BATTERY VALVES (INC. PANELS)
AUG 2017
3-WAY ADJUSTABLE ACTIVE CROSSOVER
SEPT 2017
3-WAY ADJUSTABLE ACTIVE CROSSOVER PANELS
SEPT 2017
3-WAY ADJUSTABLE ACTIVE CROSSOVER CASE PIECES SEPT 2017
6GHz+ TOUCHSCREEN FREQUENCY COUNTER
OCT 2017
KELVIN THE CRICKET
OCT 2017
6GHz+ FREQUENCY COUNTER CASE PIECES (SET)
DEC 2017
SUPER-7 SUPERHET AM RADIO PCB
DEC 2017
SUPER-7 SUPERHET AM RADIO CASE PIECES
DEC 2017
THEREMIN
JAN 2018
PROPORTIONAL FAN SPEED CONTROLLER
JAN 2018
WATER TANK LEVEL METER (INCLUDING HEADERS)
FEB 2018
10-LED BARAGRAPH
FEB 2018
10-LED BARAGRAPH SIGNAL PROCESSING
FEB 2018
TRIAC-BASED MAINS MOTOR SPEED CONTROLLER
MAR 2018
VINTAGE TV A/V MODULATOR
MAR 2018
AM RADIO TRANSMITTER
MAR 2018
HEATER CONTROLLER
APR 2018
PCB CODE:
18107151
04108151
16101141
01107151
1510815
18107152
01205141
01109111
07108151
03109151/2
01110151
19110151
19111151
04101161
04101162
01101161
01101162
05102161
16101161
07102121
07102122
11111151
05102161
04103161
03104161
04116011/2
04104161
24104161
01104161
03106161
03105161
10107161
04105161
04116061
07108161
10108161/2
07109161
05109161
25110161
16109161
16109162
11111161
01111161
07110161
05111161
04110161
01108161
11112161
11112162
04202171
16110161
19102171
09103171/2
04102171
01104171
04112162
24104171
07104171
01105171
01105172
SC4281
05105171
18106171
SC4316
18108171-4
01108171
01108172/3
SC4403
04110171
08109171
SC4444
06111171
SC4464
23112171
05111171
21110171
04101181
04101182
10102181
02104181
06101181
10104181
Price:
$2.50
$2.50
$7.50
$15.00
$15.00
$2.50
$20.00
$15.00
$7.50
$15.00
$10.00
$15.00
$15.00
$5.00
$10.00
$15.00
$20.00
$15.00
$15.00
$7.50
$7.50
$6.00
$15.00
$5.00
$5.00
$15.00
$15.00
$5.00
$15.00
$5.00
$5.00
$10.00
$10.00
$15.00
$5.00
$10.00/pair
$20.00
$10.00
$5.00
$5.00
$2.50
$10.00
$5.00
$7.50
$10.00
$12.50
$10.00
$10.00
$12.50
$10.00
$2.50
$15.00
$15.00/set
$7.50
$12.50
$7.50
$2.50
$7.50
$12.50
$15.00
$15.00
$10.00
$15.00
$5.00
$25.00
$20.00
$20.00/pair
$10.00
$10.00
$10.00
$15.00
$25.00
$25.00
$12.50
$2.50
$7.50
$7.50
$5.00
$10.00
$7.50
$7.50
$10.00
LOOKING FOR TECHNICAL BOOKS? YOU’LL FIND THE COMPLETE LISTING OF ALL BOOKS AVAILABLE IN THE BOOKS & DVDs” PAGES AT SILICONCHIP.COM.AU/SHOP
Capacitor Discharge Ignition works on bench but fails in vehicle
A long time ago I built the programmable CDI unit published in
the September 1997 issue of Silicon
Chip (“A high-energy capacitor discharge ignition system”; siliconchip.
com.au/Article/4837).
It was working fine as long as it
was tested on the bench. But in the
car, the Mosfet driver on the ignition
discharge side (IR2155) broke down
after a mile.
I put a new one in and tested it
bles which are clearly made to a better standard since they are unlikely
to cause signal connection problems.
But will the better cables sound better than the cheap stuff? Probably not.
Optical triggering not
working on motorbike
I have just built two High-energy Ignition systems (November-December
2012; siliconchip.com.au/Series/18),
to be driven by a Piranha trigger assembly on a Suzuki 4-cylinder motorcycle. The units work fine in test
mode but when attached to the trigger, do not operate.
All appears to be OK but when I
checked the voltage coming from the
trigger wire as I rotate the crank, the
voltage varies from 3.5-4V when not
triggered to 5V when triggered.
I would have thought the trigger
voltage should have dropped very
close to zero when the diode was conducting but this is not the case.
The difference in on and off voltages
does not seem to be enough to operate the ignition units. Has something
on the earth side of the power to the
trigger system been missed?
I cannot find a reason in the bike
itself for this voltage to exist so I am
wondering if there should be a lower value resistor in place of the 120W
current limiting resistor on the circuit board.
The trigger assembly has been
modified from original so that each
optical trigger works independently
where previously the two triggers
were wired together, so now each
box is a completely separate system.
I hope you can shed some light on
my problem.
• It may be that the infrared LED in
94
Silicon Chip
on the bench for 48 hours with no
problems. Back in the car, one mile
and then kaput. Ugh.
The only difference between
testing and running in the car was
that during testing, I was spinning
a distributor with a drill, using the
same coil but only one spark plug
directly from the high tension side
of the coil.
Now I want to use it for an old
2-stroke engine. Please give me some
the Piranha trigger is not getting sufficient current. Or maybe the ground
connection to the Piranha trigger has
a high resistance.
You may need to bench test the Piranha trigger itself first and then connect it to the ignition. If it works during bench testing, then it should work
in the vehicle, providing the wiring is
the same.
Help with identifying a
transistor
I have been asked to repair an ultrasonic cleaner. Initial checks indicated
a blown fuse which I changed but of
course, it again blew immediately.
Further investigation revealed two
shorted transistors but I have had no
luck in identifying them.
They are both stamped with G29AC
J13009-2 and are in TO-220 packages.
The circuit appears to run directly
from the mains input. I hope you can
help because, as usual, I don't have
a circuit diagram. (G. C., Moss Vale,
NSW)
• We suspect they are FJP13009H2TU high-voltage, fast-switching NPN
transistors. The data sheet indicates
the device marking code is J13009-2.
Trickle charging NiCad
cell in 2007 Level Meter
I have been using the PIC-based
Water Tank Level Meter, described in
the November & December 2007 and
January 2008 issues, for many years
(siliconchip.com.au/Series/46).
However, I got tired of replacing the
alkaline cell powering it. So I decided
to switch to a NiCad cell with a mains
power supply to keep it charged. This
is where all my problems started.
Celebrating 30 Years
tips on how to tackle this. (L. A.,
Stavsjö, Sweden)
• The IR2155 drivers are prone to
failure due to static electricity discharge and have been discontinued
by the manufacturer. The L6571AD
is a far more robust IC and should be
used instead of the IR2155.
An updated version of the CDI
which uses the L6571 is in the December 2014 and January 2015 issues
(siliconchip.com.au/Series/279).
I fitted the NiCad cell connected a
mains DC supply in place of the solar
cell shown in Fig.8 on page 37 of the
November 2007 issue but the unit no
longer works.
If I supply 3V it draws 1A and if I
supply 5V it draws 2A which seems
too high. What size power supply
can I use?
• You need to replace diode D2 with
a 1kW resistor to limit the current into
the rechargeable cell. Without this diode, the supply polarity is critical, so
make sure the positive output of the
plugpack goes to the + input.
With the limiting resistor, 3V or 5V
DC is fine although you could go as
high as 12V for more charge current
(but you may need a higher wattage
series resistor).
List of amplifier
projects wanted
Do you have a listing of all amplifier projects from EA, ETI and Silicon
Chip? (R. G., Bellbowrie, Qld)
• We don't have a listing of Silicon
Chip amplifier projects but it is pretty
easy to make one. Just go to our website, click on Articles, then Contents
Search, tick the Project box for article
type and then type in "amplifier" in
the Name field. You will get a list of
136 project articles.
If you want to look at amplifier projects for EA, click on Indexes, and then
"EA projects from 1968-2000". The first
part of the listing is devoted to audio
projects, including amplifiers.
Searching ETI projects is a bit more
troublesome. Again, click on Indexes,
then "ETI Index, 1971-1990". This gives
the total project list. You could grab the
text and put it into a text file and then
do a search for amplifier projects. SC
siliconchip.com.au
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Shop stocks hard-to-get project parts,
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WARNING!
SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such
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
for projects which are used in such a way as to infringe relevant government regulations and by-laws.
Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the
Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable.
siliconchip.com.au
Celebrating 30 Years
April 2018 95
Coming up in Silicon Chip
El Cheapo Modules – RF attenuators
Advertising Index
Altronics.................................. 66-69
Jim Rowe describes a programmable, 63-step, 4GHz RF digital step attenuator module with a range of applications.
Aussie Rechargeable Irons.......... 83
Gut Gas Sensors
Dave Thompson........................... 95
This innovative technology from an Australian university allows doctors to monitor gas levels in the digestive system of patients in real-time. Patients could
even potentially go home and come back later as data is logged to a mobile
phone via Bluetooth. The logged data can then help diagnose digestive ailments.
Digi-Key Electronics....................... 3
Introduction to programming the Cyprus CY8CKIT
This low-cost module incorporates a 32-bit microcontroller and a set of
reprogrammable analog circuitry which can be used for a wide range of tasks.
We show you how to use the free Integrated Development Environment.
Magic eye display for audio systems
Blamey Saunders hears................. 7
Emona........................................ IBC
Freetronics................................... 13
Hare & Forbes.......................... OBC
Jaycar.............. IFC,45-52,CATALOG
Keith Rippon Kit Assembly........... 95
LD Electronics.............................. 95
LEACH Co Ltd.............................. 25
Retro is cool and you can't get much more retro than a 6E1P magic eye valve
(electron-ray indicator). It glows green with a dancing pattern that varies with
the audio signal applied. Use it as an audio level indicator or just for a fun display to spice up your sound system.
LEDsales...................................... 95
USB Port Protector
Pakronics..................................... 57
If you're developing an Arduino (or similar) project using a PC or laptop and
powering it from a USB port, it is possible to accidentally damage your computer. We learned this the hard way. Our low-cost Port Protector greatly reduces the risk by preventing voltages outside the acceptable range from reaching your USB port.
Premier Batteries......................... 12
Note: these features are planned or are in preparation and should appear
within the next few issues of Silicon Chip.
Silicon Chip Subscriptions.......... 21
The May 2018 issue is due on sale in newsagents by Thursday, April 26th.
Expect postal delivery of subscription copies in Australia between April
26th and May 10th.
Master Instruments........................ 9
Microchip Technology.............. 11,35
Ocean Controls............................ 10
Rohde & Schwarz.......................... 5
Sesame Electronics..................... 95
Silicon Chip Online Shop....... 92-93
The Loudspeaker Kit.com.............. 8
Tronixlabs..................................... 95
Vintage Radio Repairs................. 95
Wagner Electronics...................... 33
Notes & Errata
Full Wave 10A Motor Speed Controller, March 2018: The mains Active wiring to the fuse holder shown in Fig.2 should
show the incoming mains wire (brown) connecting to the tip of the fuse holder rather than the side ring terminal. The wire
through the current transformer should then connect to the side ring terminal of the fuse holder. Also, the paragraph before the “Current Feedback” cross-heading on page 39 refers to pin 2 connecting to the 4.7nF capacitor. It should say pin 5.
These errors have been fixed in the online edition.
Budget Senator Loudspeakers, May-June 2016: in the May issue, on page 39: the dimensions given in Figs.4 & 5 are
wrong. The correct dimensions are given on page 77 of the June 2016 issue. The dimensions should be: top → 417 x 336,
front → 730 x 300, rear → 720 x 300, sides → 730 x 417, base → 300 x 381. All other dimensions are the same, and the
MDF board thickness is still 18mm.
Making Power From Rubbish, February 2018: there is an error in the fourth paragraph. The generator produces 52MW,
not 52MWh per year.
Circuit Ideas Wanted
Got an interesting original circuit that you have cleverly devised? We will pay good money to feature it in Circuit Notebook. We can pay you by electronic funds transfer, cheque or direct to your PayPal account. Or you can use the funds
to purchase anything from the SILICON CHIP on-line shop, including PCBs and components, back issues, subscriptions
or whatever. Email your circuit and descriptive text to editor<at>siliconchip.com.au
96
Silicon Chip
Celebrating 30 Years
siliconchip.com.au
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