This is only a preview of the October 2002 issue of Silicon Chip. You can view 28 of the 96 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Articles in this series:
Items relevant to "Speed Controller For Universal Motors":
Items relevant to "PC Parallel Port Wizard":
Items relevant to ""Whistle & Point" Cable Tracer":
Items relevant to "Build An AVR ISP Serial Programmer":
Purchase a printed copy of this issue for $10.00. |
when displaying the full eight bars
from white to black. When I switch
S4 from grey scale to colour, it tries to
change but remains grey scale. Varying
VR2 and VC1 made no changes whatsoever to the colour scale when testing
it on my small colour TV.
There don’t appear to be any obvious solder bridges on the SMD IC10 on
the underside of the PC board and all
voltages check OK as per the testing
procedures specified in the magazine
article. (D. S., via email).
The lack of colour may be due
to the delay time set by the 2.2kΩ
resistor between pins 8 of IC11b and
3,4&5 of IC11c. Try changing the 10nF
(0.01µF) at the IC11c inputs to a larger
value.
Also the 270pF capacitor added at
IC10’s pin 16 input may need to be
made slightly larger in value to obtain
colour.
•
Cranking difficulties
with Austin A1300
I have a problem with the High
Energy Ignition project described in
the June 1998 issue. I have installed
it in an Austin 1300 which is used
infrequently. The circuit produces
no spark while the starter motor is
cranking the engine. I can only start
the engine by towing/rolling down a
hill or changing over to the HEI once
the engine is warm when the engine
will run once the ignition switch is
released to the running position. What
can I do? (G. P., via email).
We assume you are using points
ignition. The HEI should work even if
the battery voltage drops to 6V while
cranking. How far does your battery
drop? Also check the points gap. Rubbing block wear can reduce the gap to
nil. We suggest that you use a larger
points gap than specified, to ensure a
“clean and fast break” in the points
current even when cranking slowly.
•
LiL Snooper Camera
switcher
I am interested in building the Li’L
Snooper camera switcher from the
June 2001 issue of SILICON CHIP. I
have one question though. The cameras to be used with it are both colour. Is
this circuit be suitable for colour cameras; one is CCD, the other is CMOS?
If not, can you recommend any mods
to make it suitable? (C. L., via email).
www.siliconchip.com.au
Notes & Errata
Multi-purpose Fast Battery Charger: June and July 2001. When
charging older cells either singly
or in series, it is important to ensure that their contacts are clean to
prevent voltage drops across these
connections.
High resistance connections will
prevent the charger from operating
correctly as it will detect a high
voltage per cell and simply indicate
“no Battery”.
In addition the connecting leads
from the charger to the cell or cells
must be rated at 7.5A or more and be
no longer than necessary to prevent
voltage drops.
K-Type Thermocouple Thermometer/Thermostat, August 2002: The
display reading and the thermostat
trip point can be affected by RF
signals produced by portable and
mobile telephones when these are
close to the unit. This problem can
be cured with the addition of four
100nF (0.1µF) ceramic capacitors
and a 1kΩ resistor.
The 1kΩ resistor is placed in series
with the probe input connecting
to pin 3 of IC1 while one 100nF
capacitor connects between pin 3
and pin 4 of IC1. This forms a low
pass filter in the input circuit.
The second 100nF capacitor connects between pin 3 of IC1 and
ground which is the thicker PC
track adjacent to the 10µF capacitor
The Snooper will work with any
•camera
which delivers a 1V composite
video signal.
Low sensitivity in Theremin
I have recently built the Theremin
project from the August 2000 issue of
SILICON CHIP. It works well but I find
the sensitivity and range of the pitch
antenna low. This is also the same
case with the volume disc but this is
not such a problem.
I have earthed myself to the ground
plane of the project and this helps but
it is still limiting. I was wondering if
there is a circuit modification I could
do to improve this? This web site
http://www.maxiespages.com has
to the left of IC1. The third 100nF
capacitor connects between pins 2
and 3 of IC1. The 100nF MKT polyester capacitor connecting between
pins 6 and 2 of IC1 (located to the
right of IC1 on the PC board) is removed. The fourth 100nF ceramic
capacitor connects between pins 2
and 3 of IC2.
To provide for these changes,
we have modified the PC board, as
shown in this diagram. The modified PC board is coded 04208022
and is available on our website.
Atmel AVR ISP Programming
Adaptor (October 2001): The
software referred to in the article,
avr_isp.zip, is no longer available
from the Atmel website. A suitable
alternative is “Ponyprog”, available for free download from http://
www.lancos.com/prog.html This
program also supports Windows
NT/2000 and can program many of
the newer AVR devices.
To configure Ponyprog to work
with the ISP Programmer, set it up
for the “AVR ISP (STK200/300) parallel port interface” as described in
the included documentation.
Digital Storage Logic Probe, August
2002: the outputs of the 4N25 optocouplers on the circuit on page
24 should be pins 4 & 5, not 5 & 6.
The PC board diagrams are correct
in this regard.
many circuit diagrams but none like
your unique design. (T. H., via email).
Sensitivity to hand movement is
dependent on careful tuning of the
Theremin adjustments. However,
sensitivity is not extreme and is not
meant to be. The original Theremins
required the hand to be brought very
close to the plate or vertical wire for
best pitch and volume changes.
Note that positioning of the Theremin is important and it should not
be located near to metal surfaces. Also
attaching the lid of the Theremin onto
the box can alter tuning and readjustments may be required on a trial and
error basis.
A larger diameter plate and larger
diameter antenna can also improve
sensitivity.
SC
•
October 2002 91
|