This static switch or triac contactor was obtained from Philips 1969 documentation. The SCR is from the era, but modern equivalents depending on the load can be used.
We found this circuit with JFETs in a Radio Electronics magazine from June 1969. The circuit has...
Indicated for frequency measurements, this circuit can operate with inputs up to 1 MHz. We found...
This general-purpose transistor audio amplifier was found in the March 1990 issue of Radio...