This small switched regulator was found in an 60’s Optical Electronics. The circuit uses an integrated from the time, which is difficult to obtain today.
This circuit fires by burning the fuse when the input voltage exceeds the value referenced by the zener....
The UAA180 integrated circuit is no longer manufactured, but if the reader finds one in a scrap...
We find this circuit in a Radio Electronics of July 1984. It consists of the traditional version of 1 A...