Found in a Popular Electronics from the 90s, this circuit applies to flashes with xenon lamps. The transistor admits equivalent and the phototransistor is of the Darlington type.
This circuit is from the 1977 GE semiconductor manual. The components used are uncommon today....
This circuit has 4 operating modes and was found in the 1995 Encyclopedia of Electronic Circuits...
The voltage of 30 V indicated in this project, shown in the figure, depends on the diac used. It...