Elenco Electronic Playground 50-in-1 Experiments - Manual (Page 49)

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Connect the wires according to the Wiring Checklist and
press the switch. You hear a sound like raindrops. The
variable resistor (VR) knob controls the rain, turn it to the
right to make a drizzle and turn to the left to make the rain
come pouring down. If you find it inconvenient to turn the
VR knob while pressing the switch then just connect a
wire across the switch. Do you know how this circuit works? Remember that as
you lower the oscillator’s resistance the frequency
increases, and obviously the VR controls the resistance.
What would happen if you replaced the 10K
Ω resistor
with the 100K
Ω? Try it. The rain is now very slow, and it
sounds more like a leaky faucet than raindrops.
You can experiment with changing other component
values if you like.
EXPERIMENT #31: Electronic Rain
Wiring Checklist:
o 27-to-56
o 50-to-55-to-24
o 19-to-25
o 5-to-21
o 6-to-22
o 23-to-36
o 18-to-34-to-37-to-44
o 45-to-49
o 20-to-26-to-35
Schematic