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Digital electronic thermostat with correction for triac self heating

  • US 4,741,476 A
  • Filed: 07/07/1987
  • Issued: 05/03/1988
  • Est. Priority Date: 07/07/1987
  • Status: Expired due to Fees
First Claim
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1. An electronic thermostat having a correction for self heating comprising:

  • a circuit board for supporting and interconnecting electrical parts of the electronic thermostat;

    a semiconductor power switching device disposed on said circuit board, controlled for selective connection of electric power to a temperature control unit;

    a first temperature sensor disposed on said circuit board at a location remote from said semiconductor power switching device, having an electrical characteristic which varies with ambient temperature;

    a second temperature sensor disposed on said circuit board at a location intermediate between said semiconductor power switching device and said first temperature sensor, having an electrical charactersistic which varies with ambient temperature;

    a temperature correction means connected to said first and second temperature sensors for generating a corrected temperature signal from the temperature indicated by the electrical charactersistic of said first temperature sensor and the temperature indicated by the electrical charactersistic of said second temperature sensor;

    a desired temperature means for generating a desired temperature signal indicative of a desired temperature;

    a control unit connected to said semiconductor power switching device, said temperature correction means and said desired temperature means for controlling the state of said semiconductor power switching device based upon the relationship of the corrected temperature signal and said desired temperature signal.

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