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.
102 March 2008
I am currently working on a
windmill project that uses the dynamo
of a car as the generator. Can someone
suggest another way or different kind of
inexpensive motor (PMDC) that will
work as a generator?
Also, what charging circuit is
required to charge a 12V, 40 amp
battery? Any suggestions to how we can
improvise our design are appreciated.
Can someone explain how the
digital-to-analog TV converters will work?
#3082 Charlie Eng
How can a functional, small
generator with voltage regulation be
built to operate on a bicycle?
I would like to use the sensor from
a laser mouse for a rotary encoder in a
robotic arm. How can I read from it,
using an MCU?
My plans are to mount it inside a
joint on the arm pointed at the side
wall, read the distance, then translate
that into rotational degrees.
#3084 Bryan Johnston
[#10072 - October 2007]
I am looking for a high brightness
LED with a peak wavelength around
680 nm. Is there anything similar to the
offerings from Cree, Seoul, Philips, etc.?
I think that you are getting a little
long in the wavelength there, almost
infrared. I did find one LED which has a
peak wavelength of 670 nm. According
to the datasheet, it puts out about 60%
power at 680 nm. Take a look at
Fort Collins, CO
[#12074 - December 2007]
How do they generate that little
yellow first down marker during TV
football games? I know it's computer
generated, but it's been driving me
nuts as to how they do this!
The yellow line is “painted” into the
video signal by a clever but complex
system called the “1st & Ten (graphics
system)” made available by Sportvision,
a NY-based company who introduced
it in 1998. During the game, it takes a
mobile van of equipment, including
seven computers and four human
operators — one spotter in the press