Rain Detector

This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system.

Schematic:




Parts:
Part Total Qty. Description Substitutions
R1 1 1K 1/4 W Resistor
R2 1 680 Ohm 1/4 W Resistor
D1 1 1N4001 Silicon Diode
BZ1 1 12V Buzzer
S1 1 SPST Switch
SCR1 1 C106B1 SCR 106CY
SENSOR 1 See Notes
MISC 1 Board, Wire, Case,
PC Board (For Sensor)

Notes

1. The sensor is a small piece of PC board etched to the pattern showen in the schematic. The traces should be very close to each other, but never touching. A large spiral pattern would also work.

2. Make sure to use a loud buzzer.

Source Aaroncake.net