R1 may be 10k and R2 100k. The transistor can be the BC548 and instead of the small lamp we can use a series LED with a 1k resistor. D1 is germanium and C1 is 10 nF. C2 can be 47 nF.
The contact of the sensor with water or humidity causes the relay to close its contacts. The...
This siren was found in a 1980s documentation. The circuit makes use of very old operational that were...
This circuit was obtained from Motorola documentation from 1969. The setting applies to other...