Method for powering telephone apparatus and telephone apparatus powered directly from the telephone line without external power
First Claim
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.
0 Assignments
0 Petitions
Accused Products
Abstract
A telephone apparatus powered directly from the telephone lines without external power includes a current converter in which current from a telephone line is limited by a transistor, current-sense resistor, and optical coupler acting together as a constant current device. This limited current is then converted from direct current (d.c.) to alternating current (a.c.) at the primary of a current transformer by power switching transistors driven by a flip-flop which is in turn driven by a free-running constant frequency oscillator. The alternations are symmetrical and their period or timing controlled so the current transformer does not saturate, thus maintaining maximum efficiency of conversion. The transformer outputs, after being rectified and filtered, are isolated from the primary, and provide d.c. current to maintian the charge on a battery across one output and to power telephone circuitry within a telephone device connected to the d.c. outputs. An optical coupler acting as an isolated current switch turns the constant current device off and on to facilitate pulse dialing. The current converter boosts the low telephone line current to a higher current or voltage for use by telephone devices such as pay phones, key phones, modems, or other telephone line connected devices.
-
Citations
25 Claims
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
-
-
20. A method of powering a telephone device directly from telephone lines without external power, including the steps of:
-
providing an isolation transformer having a primary winding and at least one secondary winding; limiting a current drawn from said telephone lines to produce a constant current output; alternately applying said constant current output to said primary winding at a substantially constant frequency and substantially constant duty cycle; regulating voltages on all windings of said transformer by regulating a voltage on one of said at least one secondary winding; applying regulated voltages of each of said at least one secondary winding to the telephone device to power the telephone device. - View Dependent Claims (21, 22)
-
-
23. 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, including a chargeable battery, 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. - View Dependent Claims (25)
-
-
24. A method of powering a telephone device directly from telephone lines without external power, including the steps of:
-
providing an isolation transformer having a primary winding and at least one secondary winding; limiting a current drawn from said telephone lines to produce a current limited output; alternately applying said current limited output to said primary winding at a substantially constant duty cycle; regulating voltages on all windings of said transformer by regulating a voltage on one of said at least one secondary winding by storing energy in a battery connected across said one of said at least one secondary winding; applying regulated voltages of each of said at least one secondary winding to the telephone device to power the telephone device.
-
Specification