Snap Circuits 750-in-1 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 10µF 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 10KΩ resistor (R4) with the 1KΩ (R2) or 5.1KΩ
(R3) resistors to speed up the rain.
Electronic Rain