Found in American documentation from the 1980s, this circuit makes use of components of the time, which are uncommon today. The circuit detects the approach using a sensor formed by metal plates.
This simple transistorized radio for listening on a crystal phone was found in a Japanese...
This very high voltage generator (VHV) uses a 555 and a power transistor with a heat sink. The...
Found in a 1969 documentation, this circuit is reset by a push button. The activation time is 100...