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Electronic delay timer

  • US 4,714,977 A
  • Filed: 06/05/1987
  • Issued: 12/22/1987
  • Est. Priority Date: 02/19/1985
  • Status: Expired due to Term
First Claim
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1. A machine tool timing relay having immunity from electrical noise on a control signal comprising:

  • an oscillator capable of generating pulses having a predetermined frequency;

    means for adjusting said predetermined frequency over a continuous range of frequencies;

    a counter capable of counting said pulses and capable of generating an output signal after a predetermined number of said pulses are counted;

    means responsive to a start signal for initiating said counter to count said pulses;

    an optical isolator circuit, responsive to said control signal for generating a light, detecting said light, and generating said start signal in response to said detecting said light in order to isolate said counter from electrical noise mixed with said control signal;

    an electrical contact; and

    an output circuit responsive to said output signal for operating said electrical contact when said counter generates said output signal so that said contact is operated after said counter counts a predetermined number of said pulses, thereby providing control over said contact after an interval of time required for said oscillator to generate said predetermined number of said pulses, and said means for adjusting said frequency providing continuous adjustment of said interval of time.

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