This circuit uses a photo-SCR or LASCR that is not a common component today. The relay depends on the load, and the power is supplied by the power grid.
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...