Abstract: In operation of an electrostatic spray gun through a low-valued series resistor, a circuit is employed providing voltage regulation to maintain the ionization current substantially constant. This is achieved through a feedback loop providing negative feedback to a voltage regulator so that as the current tends to increase, the voltage is reduced. The circuit provides an oscillator driven amplifier feeding a voltage rectifier and multiplier to drive the gun; the voltage regulator controlling the voltage output of the amplifier and thereby of the gun.