Importance

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Abstract

A thermostat for generating control signals for a furnace, air conditioner, or the like, employs a constant frequency periodically alternating electrical source and an oscillator incorporating an element having a thermal-sensitive electrical characteristic so the oscillator frequency varies as a function of the ambient temperature. A comparator receives the two outputs and generates a signal representative of the ambient temperature. The stable output is also provided to dividing circuits to generate a signal representative of the time that is used to interrogate a digital memory storing a desired temperature-time program for the thermostat for a repetitive period, such as a week or month. The ambient temperature signal is compared with the desired temperature signal to generate an output conrol signal. A display provides a read-out of time and temperature and is used along with keyboard or the like in programming the memory.

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First Claim