Project #512, Siren project #513, Electronic rain – Elenco Upgrade Kit SC100 to SC750 User Manual

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Project #512

OBJECTIVE: To make a siren that slowly starts up and fades
away.

Turn on the slide switch (S1), and then press the press switch (S2) for
a few seconds and release. A siren starts up and then slowly fades
away as the 10

μF capacitor (C3) discharges.

Siren

Project #513

OBJECTIVE: To make a low-frequency oscillator.

Build the circuit and turn on the slide switch (S1), you hear a sound like
raindrops. The adjustable resistor (RV) controls the rain. Turn it to the
left to make a drizzle and turn to the right to make the rain come
pouring down.

You can replace the 10K

Ω resistor (R4) with the 1KΩ (R2) or 5.1KΩ

(R3) resistors to speed up the rain.

Electronic Rain