11
Spinning Rings
Setup: Cut out the disc on page 29 that looks like the one shown here.
Using Scotch tape, attach the disc with the printed side up on the top
of the fan blade. Place the blade on the motor as shown to the left
and below.
When the press switch (S2) is pressed, the arcs will turn into colored
rings with a black background. Notice how the color drops in brightness
when it is stretched to make a complete circle.
Use the circuit from Project 82.
Setup: Place the spinning rings under a uorescent light that runs
on normal house current. Start the disc spinning and release the
press switch (S2). As the speed changes you will notice the white
lines rst seem to move in one direction then they start moving in
another direction. This effect is because the lights are blinking 60
times a second and the changing speed of the motor is acting like a
strobe light to catch the motion at certain speeds. To prove this, try
the same test with a ashlight. The light from a ashlight is constant
and if all other lights are out, you will not see the effect that looks
like a helicopter blade in a movie. Some uorescent lights use an
electronic ballast and they also produce a constant light.
Project 83 Strobe the House Lights
Project 82
WARNING: Moving parts. Do not touch the fan
or motor during operation.
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