Motor Speed Detector

Project Number: 118

OBJECTIVE: To show how to make electricity in one direction.

Description: When building the circuit, be sure to position the motor (M1) with the positive (+) side snapped to the 470uf capacitor (C5). Turn on the slide switch (S1), nothing will happen. It is a motor speed detector, and the motor isn't moving. Watch the LED (D2) and give the motor a good spin CLOCKWISE with your fingers (don't use the fan blade); you should see a flash of light. The faster you spin the motor, the brighter the flash will be. As a game, see who can make the brightest flash. Now try spinning the motor n the opposite direction (counter-clockwise) and see how bright it is -- it won't flash at all because the electricity it produces flows in the wrong direction and won't activate the diode. Flip the motor around (positive (+) side snapped to the 3-snap wire) and try again. Now the LED lights only if you spin the motor counter-clockwise.