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.
This simple circuit makes use of neon lamps to indicate the voltage of a power grid. The lamps are...
In the figure we show how to implement a TTL photo-trigger with the 7413. This circuit can be used...
This circuit is indicated for supplying the CB17495E transmitter. The BD135 must have a small heat...