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Elenco Electronics 202 User Manual

Page 65

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Project #137

Ambulance Symphony

Project #136

Police Car Symphony

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OBJECTIVE: To combine sounds from the integrated circuits.

OBJECTIVE: To combine sounds from the music, alarm, and
space war integrated circuits.

Modify the circuit from project #136 to match the circuit shown on the
left. The only differences are the connections around the alarm IC
(U2). It works the same way.

Build the circuit shown and note that in some places parts are stacked
on top of each other. Turn it on and press the press switch (S2) several
times and wave your hand over the photoresistor (RP) to hear the full
spectrum of sounds that this circuit can create. Have fun!

Do you know why the antenna (A1) is used in this circuit? It is being
used as just a 3-snap wire, because it acts like an ordinary wire in low
frequency circuits such as this. Without it, you don’t have enough
parts to build this complex circuit.