GB940006A - Improvements in temperature regulating apparatus - Google Patents

Abstract

940,006. Automatic temperature control systems. REGULATOR A. G. Nov. 30, 1961 [Dec. 2, 1960] No. 42911/61. Heading G3R. An automatic control system for an air conditioning plant using thermistors as temperature sensitive elements in which on one side of a set temperature a first thermistor is operative and a second thermistor is inoperative while on the other side of the set temperature, the functions are interchanged, comprises a bridge circuit having resistive impedances R8-10 and thermistor R11, with resistive impedances R12 14.15, and a thermistor R13 connected across the diagonals, R15 being in series with a directionally sensitive impedance such as a diode D or transistor. When function J is higher in potential than point G, the diode is blocked and R13 controls the output, but when J is lower than G, R11 will be effective. The conduction potential of point K is modified by two other bridges B<SP>1</SP>3, B<SP>11</SP>3, responsive to outside temperature, selectively connected through a switch O which is moved responsively to whether the temperature is rising or falling through a datum such as 20‹ C. i.e. for winter or summer operation. This arrangement will provide differential regulation. A modification is described (Fig 7 not shown) which will give absolute regulation. The bridge may be fed with D.C., or a pulsating D. C. which may control the conditioning apparatus through a capacitor and phase sensitive amplifier.