We find this circuit in an old documentation, but it can be made using modern transistors. The circuit trips, producing a continuous sound when the sensor is wet. The 1 mOhm resistor is actually 1 Mohm.
The circuit we use makes use of Linear Technology's LT3080 (www.linear.com) which consists of a...
This circuit is from Popular Electronics from the 90s. The integrated circuit is not very common...
This traditional triac power control circuit can control loads up to 1000 W. The triac must be...