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.
Found in an old American publication, this circuit is intended for audio experiments. The...
This battery-powered micropower supply was shown in Radio Electronics magazine in 1991. The...
This power supply for model railroad was found in a February 1961 Radio Electronics Magazine. The...