This is a READER-TO-READER Column.
All questions ANDanswers are submitted by Nuts&Volts readers and are intended to promote the exchange of ideas and provide assistance
for solving problems of a technical nature. Questions are subject to editing and will be published on a space available basis if deemed suitable
by the publisher. Answers are submitted by readers and NO GUARANTEES WHATSOEVER are made by the publisher. The implementation of
any answer printed in this column may require varying degrees of technical experience and should only be attempted by qualified individuals.
Always use common sense and good judgement!
All questions and answers should
be sent by email to forum@nuts
volts.com All diagrams should be
computer generated and sent with your
submission as an attachment.
To be considered, all questions should relate
to one or more of the following:
❶ Circuit Design
❷ Electronic Theory
❸ Problem Solving
❹ Other Similar Topics
■ Be brief but include all pertinent
information. If no one knows what you're
asking, you won't get any response (and we
probably won't print it either).
■ Include your Name, Address, Phone
Number, and email. Only your Name, City,
and State will be published with the
question, but we may need to contact you.
■ No questions will be accepted that offer
equipment for sale or equipment wanted to
■ Selected questions will be printed one
time on a space available basis.
■ Questions are subject to editing.
■ Include in the subject line of your email,
the question number that appears directly
below the question you are responding to.
■ Payment of $25.00 will be sent if your
answer is printed. Be sure to include your
mailing address or we cannot send payment.
■ Only your Name, City, and State, will be
printed, unless you say otherwise. If you
want your email address included, indicate
to that effect.
■ Comments regarding answers printed in
this column may be printed in the Reader
Feedback section if space allows.
94 March 2009
Does anyone have any schematics
and info on building a plasma speaker?
I have seen
some of the details regarding the driver
and other info is not stated.
#3091 Bill Lost
Detecting a Fault on a High-Side
I am designing an H-bridge motor
driver using two STMicro L6384 drivers,
and four VNV35N07 OMNIFETs. Since
the OMNIFETs are internally protected,
I hope to avoid using sense resistors for
fault detection. Please suggest an
elegant way to detect faults on the
highside. If a highside VNV35N07 has
clamped the gate, what is a good way
to detect this and produce a 5V logic
level signal referenced to ground?
Power supply to the H-bridge will
usually be 24 VDC, though it could be
anywhere from 6V to 30V.
#3092 James Smith
Matching Transistor Gains
I am looking for a practical vs. exotic bench setup to determine the gain of
some power TO- 3 transistors. I'm working with an old piece of equipment that
requires matched transistor sets. It was
going to be replaced in the near future,
but “near” is beginning to look like
"someday." So, for the indefinate future,
we need to keep the existing units alive
and the dead ones restored.
#3093 David Bassett
I have designed and built a USB
dumb data terminal for Time and
Attendance tracking. My problem is
that now that the device is in production, static discharge to the device
resets the MCU. It's a very simple
design using only an LCD, PIC chip,
membrane switch (with grounding
layer), a plastic enclosure, and a USB
cable to connect to the computer. I
have a grounding layer on the PCB and
the cable's shield and the membrane
grounding layer are connected to it.
Routing the membrane grounding layer
to the cable shield bypassing the PCB
ground improves ESD performance, but
not completely. What should I be doing?
#3094 Michael Lange
Voltage Regulators for Bicycle
I have an electric bicycle that runs
on 36 VDC and would like to make a
circuit that would power the lights and
radio on the bike. There are four items
all powered by various quantities of
There is 1@6V, 1@ 4.5V, and 2@3V.
If someone could provide me with a