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 sounds when the input voltage drops below the value determined by the zener. The...
May 2017 - Mouser Electronics supplies a wide range of sources for LEDs from Mean Well with inputs for...
This 2mA source was found in a 1968’s Philips documentation. The transistor may be the BC549. |...