Current and voltage control for electronic microbicidal devices

摘要

The output current of an electronic microbicidal device is used to control its voltage-generating circuitry in such a way as to maintain a constant output current despite a varying load resistance. In one manifestation of the circuitry the magnitude of the current flowing in the output circuit of the said device is used to control a transconductance amplifier 13 which determines the operation of a pulse-width control circuit 8 to modify the signal from an oscillator 7 before it is fed to a drive element 9 which controls a switching element 10 feeding a voltage multiplier 11 connected to an ion-emitting element 1. This ion-emitting element is approximated to a conductive surface 5 which is connected to the opposite pole of the voltage generator from that to which the ion-emitting element is connected and the current flowing in the output circuit thus formed is sensed by a current-sensing element 12 whose output controls the transconductance amplifier 13 in such a way as to maintain as far as possible a constant current n the output circuit. A voltage limiter 14 modifies the behaviour of the transconductance amplifier 13 in such a way as to limit the width of the pulses emerging from the pulse-width control circuit 8 and thus the output voltage of the voltage generator.