This circuit, with printed circuit board included, is from a Radio Electronics magazine from July 1971. The SCR can be any equivalent of the 106 series.
This circuit automatically switches the mains voltage to a transformer. The circuit is from 1997...
This different circuit was found in a Radio Electronics from August 1965. It works with a voltage of...
This step-down converter with 10 to 60 V input produces a 5 V output with a maximum current of 5...