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Two-terminal multiplexable sensor

  • US 4,791,311 A
  • Filed: 09/28/1987
  • Issued: 12/13/1988
  • Est. Priority Date: 09/28/1987
  • Status: Expired due to Term
First Claim
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1. A two-terminal multiplexable sensor comprising a silicon integrated circuit chip comprising:

  • (a) a power terminal and a ground reference terminal;

    (b) a binary counter means connected to said power terminal for counting the number of voltage pulses of one polarity that are superimposed on a DC supply voltage applied to said power terminal;

    (c) a fixed binary address code circuit means for providing a particular fixed-circuit binary-number address code by which said sensor may be distinguished electrically from other two-terminal multiplexable sensors;

    (d) an address code comparator means connected between an output of said binary counter means and said fixed address code circuit means for providing at an output thereof a match signal only when the count of said counter means matches said address code;

    (e) a switchable current source connected between said power terminal and said ground terminal and having a control input;

    (f) an ambient-field-to-electrical-signal transducer, having an output connected to said control input of said current source, for switching on said current source when the ambient field strength exceeds a predetermined amount; and

    (g) a transducer control means connected between said output of said address code comparator means and said transducerfor turning on said transducer and switching on said current source for at least one particular portion of each period during which both the ambient field exceeds said amount and the count of said counter means matches said address code, so that the current-source current occuring during said one portion of each said period provides a signal through said power terminal indicating the presence of the ambient field that exceeds said amount, andfor turning off said transducer during all other periods during which the count of said counter means does not match said address code.

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