This electronic rheostat with SCR was found in the June 1964 Radio Electronics magazine. The SCR may be a modern type and the 2W potentiometer may be 470 ohms.
Quadrature Generator for Transistor and SCR Testing This circuit was found in US 1980s...
This circuit, with output currents up to 500 mA, can stabilize or regulate the output voltage of a...
This circuit that uses only transistors that are still common was found in a 1995 documentation. The TIP41...