Elenco Snap Circuits® Deluxe Sound & Light Combo - Manual (Page 135)

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Project 307 Daylight Voice Echo
Note that there is a 4-snap wire under Q2, partially hidden. Place the circuit in a quiet
room with bright light shining into the photoresistor (RP). Connect the speaker (SP2)
using the red & black jumper wires, then hold it away from the microphone (X1). Turn
on the slide switch (S1). If the speaker makes a whining sound that does not stop, then
you need brighter light on the photoresistor, or the room is too noisy.
Talk into the microphone, and listen the echo on the speaker. 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. You can adjust the amount of echo using the lever on the adjustable resistor (RV).
Build the circuit as shown, and turn on the slide switch (S1). Talk into the
microphone (X1) to light the color LED (D8) and hear your voice on the speaker
(SP2). Adjust the amount of echo using the lever on the adjustable resistor
(RV).
Next, replace the microphone with the press switch (S2). Push the press switch
to see light on the color LED, and hear a clicking sound from the speaker.
Project 306 Another Voice Echo Light
The photoresistor controls power to
the echo IC (U28), and acts as an
on/off switch. If there is some light on
it but not bright light, it may only
partially turn on the echo IC, causing
the echo IC to malfunction.
Also, you must hold the speaker
away from the microphone or the
circuit may self-oscillate due to
feedback. You also need a quiet
room, with low background noise.
SCC-350_Manual_Part_C.qxp 7/25/14 2:10 PM Page 23