JPS5795197A - Controlling circuit for air conditioning unit - Google Patents

Abstract

PURPOSE:To realize control without using taps by a method wherein a blower motor is run regulated by a phase controlling double throw controlling device and a reference voltage corresponding to each notch is selected by a microcomputer thereby determining a suitable phase control angle. CONSTITUTION:A double throw controlling device 1 is connected to a blower motor 2 and a signal is obtained from a lineup of a power source, a rectifying circuit 3, a zero point detecting circuit 4, and a sawteeth voltage generating circuit 5. A signal from a clock circuit 8 is inputted in a microcomputer 7 and selection is made out of the resistors 6 for the purpose of creating a reference voltage. The reference voltage is compensated by a transistor 10 discriminating between frequences 50Hz and 60Hz. A comparator 12 compares the reference signal with the sawteeth voltae and controls the double throw controlling device 1 through a trigger circuit 13. Accordingly, automatic operation is realized with a notch selected under a prescribed program, the elimination of tap changing resulting in higher controlling circuit reliability.