Elenco Snap Circuits SOUND &reg - Manual (Page 40)

Project 47 Super Optical Keyboard Echo
Project 48
Softer Optical
Keyboard
Echo
This circuit is shown on the Snap
Circuits
® Sound box cover; use
that picture to help in building it.
Use the preceding circuit, but remove the
1
m F capacitor (C7) from the circuit, or
swap it with the 0.1 m F capacitor (C2), or
replace it with the 470 m F capacitor (C5).
The sound volume is different now.
Build the circuit as shown. Turn off the left slide switch (S1), and
turn on the right slide switch. Press some of the keyboard keys
and listen to the echo. Move the lever on the adjustable resistor
(RV) to change the amount of echo (up is maximum echo, down
is no echo). Try this at different RV settings, because the effects
are very interesting with both high and low echo amounts. The
color LED (D8) will light when any green key is pressed, but will
not be very bright.
Now turn on the left slide switch to add the photoresistor (RP) to
the circuit. Wave your hand over the photoresistor to change the
sound. Try it with different levels of light shining on the
photoresistor, and at different RV settings.
Project 49 Reflection Detector
Build the circuit and turn the
slide switch (S1). Take it
into a dimly lit room, so that
the color LED (D8) is
flashing but there is no
sound.
Now hold a mirror directly
over the color LED and
photoresistor (RP). When
the mirror reflects the LED’s
light into the photoresistor,
a tone will be produced,
signaling that a reflection
was detected. The tone will
change as the LED flashes.
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