Rain alarm-door bell


Posted on Sep 10, 2012

With SI open the circuit functions as a doorbell. With SI closed, rain falling on the sensor will turn on Ql, triggering Q2 and the thyristor and activating the bell, R4 provides the holding for the thyristor while Dl prevents any damage to the thyristor from back EMF in the bell coil. The sensor can be made from 3 square inches of copper clad board with a razor cut down the center


Rain alarm-door bell
Click here to download the full size of the above Circuit.

Cl prevents any mains pickup in the sensor leads.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Hot Springs Reverb
Siren system circuit
Positive-regulator-with-pnp-boost
Pulse-dialing-telephone
Digital Vacuum Gauge
15 Watt switching power supply
hall effect switch
Numeric water level indicator- liquid level sensor circuit diagram with 7 segment display
Adventures with a Single Board Computer
Cell Phone Operated Land Rover
Photoflash



Top