Elenco Projects 102-305 - Manual (Page 11)

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Project #107
OBJECTIVE: To show how light is used to control a street lamp.
Press the press switch (S2) on and set the adjustable resistor (RV) so
the lamp (L2) just lights. Slowly cover the photoresistor (RP) and the
lamp brightens. If you place more light at the photoresistor the light
dims.
This is an automatic street lamp that you can turn on by a certain
darkness and turn off by a certain brightness. This type of circuit is
installed on many outside lights and forces them to turn off and save
electricity. They also come on when needed for safety.
Automatic
Street Lamp
Project #108
Voice-controlled Rays of Light
OBJECTIVE: To show how light is stimulated by sound.
Turn the slide switch
(S1) on. There will be
only a weak light
emitting from the green
LED (D2). By blowing
on the mic (X1) or
putting it near a radio
or TV set, the green
LED will emit light, and
its brightness changes
as the loudness
changes.
Project #109
Blowing Off the Electric Light
OBJECTIVE: To show how light is stimulated by sound.
Install the parts. The
lamp (L2) will be on. It
will be off as long as
you blow on the mic
(X1). Speaking loud
into the mic will
change the brightness
of the lamp.