This circuit was found in documentation from the 90s. The transistors can be general-purpose equivalents. The circuit has two versions, one that drives LEDs and another that drives a relay as a load.
Nothing more useful on the bench than a variable voltage source. This is the source we found in...
We found this circuit, which appears with variations on this site, in a European documentation from the...
This circuit is used to fire an auxiliary flash when the machine's main flash operates. With two...