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Semiconductor gas sensor having linearized indications

  • US 5,034,725 A
  • Filed: 07/11/1990
  • Issued: 07/23/1991
  • Est. Priority Date: 07/11/1990
  • Status: Expired due to Fees
First Claim
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1. A combination which includes semiconductor elements for measuring atmospheric concentrations of reducing gases comprising a gas sensor whose conductivity varies in accordance with variations in the concentration of ambient reducing gases, resistance means in series with said gas sensor for establishing a reference voltage, circuit means interconnecting said resistance means with the non-inverting inputs of a plurality of voltage comparators, an adjustable resistance means of a magnitude substantially equal to the response of said sensor at its maximum value, a thermistor in parallel with a fixed resistance and in series with said adjustable resistance means and with a voltage divider comprising a plurality of fixed resistors respectively connected with the inverting inputs of said plurality of voltage comparators, and a light emitting diode in series with the output of each of said comparators for selectively indicating a particular degree of ambient reducing gas concentrations.

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