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Notes & Errata
Sustain Unit for Electric
Guitars, March 1998: the
BFR84 dual gate Mosfet
(Q1) is no longer available.
The solution is to substitute
a 2N5484 N-channel FET,
as shown on the accompanying overlay diagram.
An extra 22kΩ resistor is
required to alter the level
control voltage range from
VR3 and this can be connected between pins 2 & 4
of IC2a, on the back of the
PC board. Also the 0.1µF
capacitor between pins 8 &
9 of IC1c should be changed
to .001µF.
Have I missed something? (Doug – via
email).
• The 5.25V RMS that you are obtaining at the 0dB output of the pink
noise source must be a measurement
error. This is because the circuit is
powered from a 9V battery and even
if IC1b is being over-driven, it could
only deliver about 3V RMS.
Perhaps you are measuring the DC
voltage at the output of IC1b which
should be sitting at around half supply. Check the 10µF capacitor at this
output to see if it is short circuited.
Improving the ignition
on a Honda
I have a 1994 Honda Integra VTIr
and was wondering if I could use
the Multi-Spark Capacitor Discharge
Ignition kit (September 1997) on it.
I have seen similar products on the
market such as the Crane Hi6 ignition
amplifier so I figure that this kit would
do the same thing but at a fraction of
the cost. I have provided a portion of
the installation of the Crane Hi6 for
you to read, as it looks similar to your
kit. (Thanh – via email).
• Since your car already has a very
comprehensive engine management
system which includes solid state
ignition, we cannot see the point of
fitting the Multi-Spark CDI or any
commercial aftermarket system. The
only possible justification for fitting a
higher output ignition system would
be if the engine has been substantially modified to either increase its rev
limit or its compression ratio. In our
opinion, since you already have a
highly developed engine, you would
be wise to leave it alone.
Identifying an
unknown PC board
I have a kit with a PC board number SC09111931 which has a missing
output transistor (the big one with
the heatsink). I was wondering if you
can tell me what the transistor is or
where to get information on this kit.
(Michael – via email).
• If you search in the projects index
on our website you can identify any
project from the board number. This
board was a simple low voltage speed
controller featured in the January
1994 issue. The transistor is a BD679
and can be obtained from Jaycar,
DSE, etc.
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
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JULY 1999 93
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