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Method for powering telephone apparatus and telephone apparatus powered directly from the telephone line without external power

  • US 4,803,719 A
  • Filed: 06/04/1987
  • Issued: 02/07/1989
  • Est. Priority Date: 06/04/1987
  • Status: Expired due to Fees
First Claim
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1. A telephone apparatus powered directly from a telephone line, comprising:

  • a telephone device;

    means, connectable with first and second conductors of a telephone line, for limiting current drawn from said telephone line, and for producing a constant current output;

    a transformer including a primary winding and at least one secondary winding connected to said telephone device, said at least one secondary winding being electrically isolated from said primary winding;

    switching means, connected to said constant current output, for alternately connecting and disconnecting said constant current output to and from said primary winding at a substantially constant frequency and duty cycle; and

    means connected across one of said at least one secondary winding for regulating voltages on all windings of said transformer and for producing regulated output voltages corresponding to respective ones of said at least one secondary winding.

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