Telephonic communications – Subscriber line or transmission line interface
Patent
1987-06-04
1989-02-07
Mottola, Steven
Telephonic communications
Subscriber line or transmission line interface
379413, H04M 1900
Patent
active
048037192
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.
REFERENCES:
patent: 3336521 (1967-08-01), Russell
patent: 4030014 (1977-06-01), Chana et al.
patent: 4254459 (1981-03-01), Belson
patent: 4380687 (1983-04-01), Stewart
patent: 4395590 (1983-07-01), Pierce et al.
"Designer's Casebook", Electronics, Apr. 12, 1971; by Stig R. Hjorth.
"Understand FCC Rules when Designing Telecomm Equipment"; EDN, May 16, 1985, Glen Dash, Dash, Straus and Goodhue Inc.
"IC-Modem/Phone-Network Interfaces Meet FCC Isolation, Protection Rules", EDN, Mar. 22, 1984, R. Chirayil and P. Ehlig.
"Single-Chip Reportory Dialer Affords Dual-Dial-Mode Telephone", EDN, Mar. 22, 1984, Darin L. Kincaid and David N. Larson.
General Digital Corporation, GEN-II Pay Telephone, 1985.
LandOfFree
Method for powering telephone apparatus and telephone apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for powering telephone apparatus and telephone apparatus , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for powering telephone apparatus and telephone apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1089809