This circuit triggers in 100 microseconds in case of excess voltage. The adjustment is made in the pot. The circuit was found in 1969 documentation.
This circuit is from an English magazine of 1977. The circuit is still current, just using BC547...
The adjustment of the maximum load voltage is made in the trimpot. The circuit is from 1994...
In the figure we have the conventional configuration of a differential amplifier with the...