Found in American documentation from the 1970s, this circuit can be designed based on a modern SCR, such as the TIC106. The SCR must be provided with a heat sink.
This circuit is from 1995 documentation. When the phone is lifted, the relay closes its contacts by...
The purpose of the circuit shown in the figure, obtained from a 1972 documentation, is to delay the...
This circuit oscillates in the fifth harmonic of the crystal frequency. The circuit is from a 90's...