Elenco Electronics 202 - Manual (Page 76)

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Project #173 Fast Fade Siren
OBJECTIVE: To produce sound of a siren driving away into the
distance.
Press the press switch (S2), the integrated circuit (U2) should make
the sound of an up-down siren that gets weaker with time. The fading
is produced by the charging of the 100
μF capacitor (C4). After it is
charged the current stops and the sound is very weak.
To repeat this effect you must release the press switch, remove the
capacitor, and discharge it by placing it across the snaps on the
bottom bar marked A & B. Then, replace the capacitor and press the
press switch again.
Project #172
OBJECTIVE: To control a motor using light.
Turn the slide switch (S1) on, the motor (M1) spins and the lamp (L2)
lights. As you move your hand over the photoresistor (RP), the motor
slows. Now place your finger onto the photoresistor to block the light.
The motor slows down. In a few seconds, the motor speeds up again.
Motor & Lamp
by Sound
!
WARNING: Moving parts. Do not touch the fan or
motor during operation.