Ticking Screecher

Project Number: 103

OBJECTIVE: To make fun sounds using light.

Description: Build the circuit as shown, and turn on the slide switch (S1). Vary the amount of light on the photoresistor (RP) by partially covering it with your hand. You can make screeching sounds by allowing just a little light to reach the photoresistor. If you replace the 10uF capacitor (C3) with a 3-snap wire or any of the other capacitors (C1, C2, C4, or C5), then the sound will be a little different.