Elenco Electronics 202 - Manual (Page 36)

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Project #55
OBJECTIVE: To build an electronic spinner.
Spinning Rings
!
WARNING: Moving parts. Do not touch the fan or
motor during operation.
!
WARNING: Moving parts. Do not touch the fan or
motor during operation.
Setup: Cut out the disc on page #49 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 (M1) as shown
on 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.
Project #56
OBJECTIVE: To use the spinner to see strobe effect due to 60
cycles.
Use the circuit from project #55.
Setup: Place the spinning rings under a fluorescent 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 first
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 flashlight. The light from a flashlight 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 fluorescent lights use an electronic
ballast and they also produce a constant light.
Strobe the House Lights