Elenco Projects 1-101 - Manual (Page 37)

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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
OBJECTIVE: To control an LED using sound.
Project #76
Use the circuit from Project #74. Connect the whistle chip (WC) to points
A1 and C1 on the base grid, then remove the photoresistor (RP). Turn
the slide switch (S1) on and clap your hands or talk loud near the whistle
chip, the LED (D1) will light. The whistle chip has a piezocrystal between
the two metal plates. The sound causes the plates to vibrate and
produce a small voltage. The voltage then activates the music IC (U1).
Project #75
Sound-Controlled Time
Delay LED
OBJECTIVE: To control an LED using a motor.
Use the circuit from Project #75. Remove the whistle chip (WC) and
connect the motor (M1) across points A1 and C1 on the base grid. Turn
the slide switch (S1) on and turn the shaft of the motor and the LED (D1)
will light. As the motor turns, it produces 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
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