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.
This circuit is used in transceivers, enabling input selection by diode switching through polarity...
This configuration was found in an American publication from the 90s. Operators admit equivalents just...
This circuit was found in an Italian magazine Elettronica Prática of 1977. The transistors can be...