The circuit shown in the figure generates pulses of up to 200 V under a current of up to 200 uA with total isolation of the input circuit. The short pulses produced by the 555 that are adjusted by the components connected to pins 2, 6 and 7 of the 555 are applied to a pulse transformer that uses a Ferrox Cube ferrite core. These pulses are taken to a triggered control circuit that employs a Monsanto SCR opto-isolator (equivalents can be tried, given the difficulties in obtaining the original type). The adjustment of the output current and voltage is done simultaneously by a double potentiometer connected to the output. The 1 nF capacitors in the output circuit determine the shape of the pulse obtained. The voltages indicated next to the diodes are the minimum peak inverse voltages required for the types used in the application. Diode like 1N4007 can be used for 400 V and 1N4004 for 200 V.
