Patent ID: 6101827
Filing Date: 2000-08-15
Classification: F25B,Y02B

Abstract:
Temperature comparison circuitry comprising: positive and negative connectors adapted to be connected to a supply of positive and negative electrical power;a first thermistor coupled to the positive connector;a second thermistor coupled to the positive connector;a first high-gain NPN transistor having a collector, an emitter, and a base coupled between the first thermistor and the positive connector by a first line, the collector of the transistor being coupled with the positive connector;a second high-gain NPN transistor having a collector, an emitter, and a base coupled between the second thermistor and the positive connector by a second line, the collector of the transistor being coupled with the positive connector; a potentiometer coupled between the emitters of the first and second NPN transistors and coupled to the negative connector;a first connection point between the first NPN transistor and the potentiometer;a second connection point between the second NPN transistor and the potentiometer;a third line running from the first connection point;a fourth line running from the second connection point, which third and fourth lines areadapted to be connected to a piece of electrical equipment which is sensitive to a change in voltage;a first fixed-value resistor coupled between the first line at a point between the first thermistor and the first NPN transistor and the third line; anda second fixed-value resistor coupled between the second line at a point between the second thermistor and the second NPN transistor and the fourth line.