Nuts & Volts - September 2006

F

O

R

U

M

TECH

This is a READER-TO-READER Column.

All questions AND answers 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.

QUESTIONS

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 buy.

■ Selected questions will be printed one time on a space available basis.

■ Questions are subject to editing.

ANSWERS
■ 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 an-
swer is printed. Be sure to include your mail-
ing 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 September 2006

>>> QUESTIONS

I have heard that florescent lights can be dimmed. The circuit is a constant voltage generator (120V) and a current controller that changes the frequency to lower the light intensity.

Can someone supply such a circuit that uses a variable frequency to change the amount of current flowing?

The original ballast is still being used in the circuit.

#9061

can get quite high for short on times?)

Here is an interesting tidbit for all Nuts & Volts readers: In copper wire, the rated current is 0.003 times the circular mils. I saw this tidbit many years ago and was too dense to grab its significance but have since "got it" and am wondering how many techs know it and use it.

#9063

Robert C. Gibson Aurora, IL

Edwin Smith via email

>>>> ANSWERS

I want to use an accelerometer as a motion sensor for a vehicle security system. I just want to measure the motion of the car.

Can someone please advise me on which accelerometer type (capacitive, temperature, etc.) is good for this application?

What are the advantages and disadvantages?

#9062

[#7064 - July 2006]

I purchased a GOLDSTAR DC power supply model GP-305. There are some LEDs, switches, and terminals that I have not been able to figure out. Can anyone tell me the function of these or have a manual I might be able to copy?

The mystery elements are:

Pono Lenyora via email

I have a question about heat dissipation vs. duty cycle. Power increases proportional to current squared, and linearly with respect to resistance. As duty cycle varies, should I use the square root of the on (off?) time to calculate power? (Is this not analogous to pulsed laser calculations where energy is related to pulse duration and