Elenco Electronics SNAP CIRCUITS SKILL BUILDER - Project 126 Sunrise Light; Sunrise Light Circuit

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Sunrise Light
Cover the photoresistor (RP) and turn on the slide switch (S1). The
LED (D1) is off, but if you wait a long time then it will eventually light
up. Uncover the photoresistor and the LED will light up in just a few
seconds. Push the press switch (S2) and reset the circuit.
The resistance of the photoresistor controls how long it takes to charge
up the 470mF capacitor (C5). Once the capacitor is charged, current
can ow into the NPN transistor (Q2) and turn on the LED. Pushing the
press switch discharges the capacitor.
Project 126