THERMOSTATIC MICROSWITCH WITH POSISTOR HEATER Russian patent published in 2001 - IPC

FIELD: temperature control for precision radio electronic devices. SUBSTANCE: thermostatic microswitch has posistor 2 mounted on controlled-temperature substrate 1 and control transistor 5 whose collector is connected to power supply and emitter, to one of posistor leads. Newly introduced in device are feedback resistor 6 inserted between posistor lead and common bus, operational error amplifier 7, and voltage dividers 8, 9, 10 that functions to determine thermostatic control temperature of posistor 2 and is connected between power supply and common bus. Output of voltage divider 9 is connected to inverting input of operational amplifier 7 whose output is connected to base of control transistor 5 and noninverting input, to feedback resistor 6. Thermostatic switch has reduced number of thermal-inertia sections and incorporates closed-circuit control system that functions to reduce voltage across posistor heater in response to its temperature increase. EFFECT: improved precision of thermostatic control within wide range of ambient temperatures. 1 dwg