This circuit indicates when the voltage of a 12 V battery is low. With changes, for example, the zener, the circuit can be used to monitor other voltages.
This circuit was found in a 1974 documentation. The bipolar transistor can be the BC548 and at the...
Among other things, this oscillator is suitable for practicing Morse code. The circuit is from a...
An interesting type of sensor for specific applications is the sensor formed by piezoelectric...