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.
- R1 1K 1/4 W Resistor
- R2 680 Ohm 1/4 W Resistor
- D1 1N4001 Silicon Diode
- BZ1 12V Buzzer
- S1 SPST Switch
- SCR1 C106B1 SCR 106CY
- SENSOR See Notes
- MISC Board, Wire, Case, PC Board (For Sensor)
- 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.
- Make sure to use a loud buzzer.
circuit from http://www.aaroncake.net/