This circuit is from an American 1964 documentation. Transistors of the time are used, but modern equivalents can be employed.
This tachometer circuit with analog indication for cars with circuit breakers was found in Radio...
Found in Radio Electronics from the 90s, this circuit converts signals from the 9.5 to 9.8 MHz...
This circuit with germanium transistors was found in a 1980s documentation. The circuit makes use...