Expert: Russ Kinner - 8/12/2005

Question
How would I put together my own little sound-activated car for 9th grade science project?  Where would I be able to find the materials to do so?

Answer
Here are 2 links to sound activated cards that can be interfaced to a small relay.  You could use the relay contacts to start and stop a car.  Steering would be more difficult but you might be able to fliter the audio input to pass low and high tones to turn left and right.

http://electronickits.com/kit/complete/elec/ck1607.htm

http://www.uoguelph.ca/~antoon/circ/relay4.html

I really don't know much about these circuits but both look to be easy to assemble (the kit version would probably be better for you as long as you can use a soldering iron).  

Making a PC board is a chore so if you wanted to build from scratch I would suggest getting a prototyping board that Radio Shack sells (Catalog #: 276-175) and use it to wire the circuits for a test.

Good Luck

Russ