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.
Using an operational amplifier with FET, this voltmeter has a high input resistance. The circuit has...
This circuit was found in a Linear Technology documentation from the 90's. The integrated circuits are...
This circuit generates signals controlled by crystal and can generate marks up to 30 MHz of 1 in 1...