This circuit was found in documentation from the 1980s. It is powered by the audio signal that must be cut. Transformers are the critical components and transistors are 2N2222.
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...