Elenco Electronics 202 - Manual (Page 44)

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Project #74
OBJECTIVE: To control an LED using light.
Cover the unit, turn the slide switch (S1) on, and notice that the LED (D1) is
on for a few seconds and then goes off. Place the unit near a light and the
LED will light. Cover the photoresistor (RP) and place it near the light again.
The LED will not turn on. The resistance of the photoresistor decreases as
the light increases.
Light-controlled LED
Project #75
OBJECTIVE: To control an LED using a motor.
Use the circuit from project #74. Connect the motor (M1) across points A1
and C1 on the base grid, then remove the photoresistor (RP). Turn the slide
switch (S1) on and turn the shaft of the motor and the LED (D1) will light. As
the motor turns, it produce a voltage. There is a magnet and a coil inside the
motor. When the axis turns the magnetic field will change and generate a
small current across its terminals. The voltage then activates the music IC
(U1).
Motor-controlled
Time Delay LED
Place the fan on the motor (M1) and turn on the slide switch (S1).
The motor spins briefly as the 470
μF capacitor (C5) charges up.
Turn off the slide switch and press the press switch (S2) to
discharge the capacitor and reset the circuit.
You can bypass the capacitor by pressing the press switch while the
slide switch is on. This lets the motor spin at full speed and also
lights the lamp.
Project #76
OBJECTIVE: To learn about a device that is used to delay
actions in electronics.
Capacitor Slow-down
!
WARNING: Moving parts. Do not touch the fan or
motor during operation.