PROTECTION CIRCUIT OF POWER SUPPLY APPLIED JUNCTION FIELD EFFECT TRANSISTOR

摘要

PURPOSE: A protection circuit of power supply applied a junction field effect transistor is provided to reduce standby power by blocking AC power according to the usage of a load. CONSTITUTION: A protection circuit(70) comprises an auxiliary power(72), a Zener diode(74), a photocoupler(76), a switch transistor(78), and a plurality of resistors. The auxiliary power supplies the voltage source for driving a JFET(Unction Gate Field-Effect Transistor). The Zener diode distinguish the size of a negative voltage provided from the auxiliary power. The photo-coupler is electrically connected to the photo transistor according to a predetermined voltage applied to a photo diode. The switch transistor runs a relay and the Resistors control the voltage and current within the protection circuit.