Elenco Electronics 202 - Manual (Page 93)

-92-
Project #217
OBJECTIVE: To connect two sound IC’s together to drive two
LED’s and a motor.
Build the circuit shown on the left. Place the fan onto the motor (M1).
In the circuit, the alarm IC (U2) and the music IC (U1) are connected
together. The sounds from both IC’s can be played at the same time.
Press the press switch (S2). The music IC plays and the green LED
(D2) lights. Now turn on the slide switch (S1) and press the press
switch again. You should hear the sounds from both IC’s playing. As
the alarm IC plays, it also drives the fan and the red LED (D1).
Sound Mixer Fan
Driver
Project #216
Photoresistor Control
OBJECTIVE: To use a photoresistor to control the brightness of
an LED.
In this circuit, the brightness of the LED (D1) depends on how much
light shines directly on the photoresistor (RP). If the photoresistor
were held next to a flashlight or other bright light, then the LED would
be very bright.
The resistance of the photoresistor decreases as more light shines on
it. Photoresistors are used in applications such as street lamps, which
turn on as it gets dark due to night or a severe storm.
!
WARNING: Moving parts. Do not touch the fan or
motor during operation.