Circuit arrangement for varying the power loss in an electrical consumer

摘要

FORM:1111734/C4-C5/1 A photovaractor (i.e. a PN junction device the junction resistance of which varies inversely with illumination and the junction capacitance of which varies inversely with the voltage across the junction) is connected in series with a parallel resistor/capacitor combination, sources of direct and alternating voltages and a load. The direct source 14 and the resistor 15 act as a constant-current source so that when the device receives illumination and its junction resistance 11 falls, the voltage across the junction falls. The resulting increase in junction capacity 10 reduces the A.C. reactance of the whole circuit and the increased A.C. flowing energizes a load 12. An image intensifier may comprise the varactor junction 18, a layer 19 acting both as resistor 15 and capacitor 16, and a ZnS electroluminescent layer 20 as the load 12 all sandwiched between electrodes 21. The resistive layer 19 may be omitted if the electroluminescent layer has the required electrical properties to take its place.