Using neon lamps, this circuit from a 1969 publication provides 17 V of maximum voltage or else adjustable.
With a unijunction transistor and a tunnel diode it is possible to obtain rise times of 1 ns with...
The adjustment of the maximum load voltage is made in the trimpot. The circuit is from 1994...
This circuit from a Radio Electronics from February 1976 activates the relay in two different ways...