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Smoke detecting apparatus

  • US 4,665,311 A
  • Filed: 08/13/1984
  • Issued: 05/12/1987
  • Est. Priority Date: 08/12/1983
  • Status: Expired due to Term
First Claim
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1. Smoke detecting apparatus comprising:

  • light sensing, solid state photocell means for producing signals in response to light;

    impedance matching buffer stage amplifier means responsive to said signals for producing an amplified signal at an impedance level adapted for further processing;

    gain controlled amplifier stage means responsive to said amplified signal and to a gain controlling signal for producing a gain controlled signal;

    output amplifier stage means responsive to said gain controlled signal for producing an output signal;

    temperature sensor means for producing a temperature signal indicative of ambient temperature;

    gain control network means responsive to said temperature signal and to said output signal for producing said gain controlling signal;

    said gain control network means being adjustable to compensate for temperature dependence of the said signals produced by said light sensing solid state photocell means; and

    means to deliver said gain controlling signal to said gain controlled amplifier stage means.

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