This circuit for old flashes with xenon lamps was found in a Radio Electronics magazine from June 1966. The sensor is a photoelectric cell from the time. Power is supplied by a 9 V battery.
We found this circuit, which appears with variations on this site, in a European documentation from the...
This circuit that drives an electromechanical counter of the time was found in Radio Electronics magazine...
Found in a Hands On Electronics of the 80s, this circuit makes use of a gas sensor of the time....