Elenco Snap Circuits SOUND &reg - Manual (Page 66)

Project 130 Day Echo Light Project 131
Day Echo
Variants
Project 132
Photo Light Timer
Build the circuit, and turn
on the slide switch (S1). If
there is light on the
photoresistor (RP) then
the color LED (D8) will be
on. Block the light to the
photo-resistor, and the
color LED should slowly
get dimmer and dimmer.
Use the preceding circuit, but replace the
microphone (X1) with the press switch (S2)
or 500k
W adjustable resistor (RV3). Press
S2 or turn the knob on RV3 to change the
light.
You can also replace the color LED (D8)
with the speaker (SP2). When used with the
microphone, you must connect the speaker
using the red & black jumper wires and hold
it away from the microphone, and also omit
C7.
Build the circuit as shown, and
place it where there is bright light
shining into the photoresistor
(RP). Turn on the slide switch
(S1). If the color LED never
turns off, then you need brighter
light on the photoresistor.
Talk into the microphone, and
see the color LED (D8) flash.
Now block the light to the
photoresistor to turn off the
circuit; slowly wave your hand
over it to turn the echo on and off
while talking. You can adjust the
amount of echo using the lever
on the adjustable resistor (RV).
Project 133
Adjustable Photo Light Timer
This circuit is similar to the
preceding one, except the color
LED (D8) stays on longer when
you block the light to the
photoresistor (RP). Use the lever
on the adjustable resistor (RV) to
set how long the color LED will
stay bright after the photoresistor
is covered.
The 470 m F capacitor (C5)
stores up some electricity,
and releases it when you
block the light.
The resistance of RV
slows down the dis-
charging of the 470
m F
capacitor (C5).
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