This power supply protection circuit was found in the December 1978 Radio Electronics magazine. The SCR is triggered by shortening the power supply and quickly blowing the protection fuse.
Found in American documentation this circuit uses transistors of the time. The circuit can be made...
This flasher with two power transistors was found in a Radio Electronics magazine from September 1961....
Found in American documentation from 1969, this circuit switches signals with a FET of the time....