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Communication via an electricity supply main

  • US 4,348,582 A
  • Filed: 03/14/1979
  • Issued: 09/07/1982
  • Est. Priority Date: 03/14/1978
  • Status: Expired due to Term
First Claim
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1. A control system for remotely controlling at least one alternating current electric-mains-operated appliance, including:

  • a controller having electronic switch means for superimposing a control signal on an alternating current mains supply by interrupting the mains supply for a period adjacent a zero crossing in one or more selected half-cycles of the mains supply and substantially less than the mains supply cycle period thereby to hold the mains supply voltage substantially at zero during said interruption;

    at least one receiver means for monitoring the mains supply and for controlling said electrical appliance said receiver having(A) interruption detector means including a full wave rectifier means for providing a full-wave rectified signal from said mains supply;

    voltage threshold detector means for receiving said full-wave rectified signal and producing an output whenever the voltage of said full-wave rectified signal is lower than a threshold voltage; and

    means for responding to the durations of said outputs from said voltage threshold detector means to produce an indication of the occurrence of a said interruption; and

    (b) means responsive to said indications of the occurrence of an interruption to produce outputs for controlling said electric appliance in accordance with the control signal from the controller.

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