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 circuit is used to power small 12V drills used in the drilling of printed circuit boards and...
This circuit uses a not easy to find IC these days. The circuit sources 15 W to a 4 ohm load and...
This sound effect for guitars uses a 555 to modulate the signal from an instgrument pick-up. The...