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Position transmitter for a pneumatic-pneumatic or electro-pneumatic converter

  • US 4,731,996 A
  • Filed: 09/10/1984
  • Issued: 03/22/1988
  • Est. Priority Date: 09/10/1984
  • Status: Expired due to Fees
First Claim
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1. A position transmitter for generating a signal corresponding to the position of a movable member of an actuator device, comprising:

  • a DC power supply having a pair of terminals;

    an input line connected to one terminal of said power supply;

    an output line connected to the other terminal of said power supply;

    voltage divider means connected between said input and output lines and having a movable contact mechanically engageable with the movable member of the actuator device for carrying a voltage which varies with motion of the movable member;

    a zero adjust amplifier having an input connected to said movable contact for receiving the voltage carried by said movable contact, and an output, said zero adjust amplifier being connected to influence a current on said output line and having an adjustable input, said movable contact being movable to a zero position corresponding to a zero position of the movable member and said adjustable input being adjusted to apply a low selected current signal to said output line which is indicative of a zero position of the movable member;

    a span adjust amplifier having an input connected to said output of said zero adjust amplifier, said span adjust amplifier having an output and being connected to influence a current on said output line, said span adjust amplifier having an adjustable input, said movable contact being movable to a maximum position corresponding to a maximum position of the movable member and said adjustable input of said span adjust amplifier being adjusted to apply a high selected current signal to said output line which is indicative of the maximum position of the movable member; and

    a voltage-to-current stage connected between said input and output lines and connected to said output of said span adjust amplifier for converting a voltage signal from said span adjust amplifier to a current signal on said output line.

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