A circuit for developing an AC ringing voltage from a DC voltage supply

A circuit for developing an AC ringing voltage from a DC voltage supply

A circuit (1) for developing an AC ringing voltage from a PBX DC line voltage supply applied across a positive main terminal (2) and ground terminal (3) comprises a H-bridge circuit (8) which includes a bridge circuit (7) having four first transistors (Q1 to Q4) which are operated by four second tra...

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Hauptverfasser: GERALD GRANT GOODALE, CAOIMHIN SOASAMH O'LAOI, CHARLES BERNARD KELLY, PETER BUSHELL, MICHAEL ANTHONY TOPE, ADRIAN MARY PIUS PHELAN, FERGAL PAUL MEATH, ANTHONY FRANCIS O'BYRNE, THOMAS BRENDAN O'GORMAN, DAVID JOHN PETER FLETCHER, THOMAS ROBERT LEYDEN, MICHAEL JOSEPH O'DWYER, DENIS MICHAEL O'DWYER, DAVID EAKIN HANNA, MARTIN FRANCIS WALSH, CONOR BRIAN MURPHY, PETER MARTIN BRADY, COLM FRANCIS MULVEY
Format: Patent
Sprache:eng
Schlagworte:
APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS
CONTROL OR REGULATION THEREOF
CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER
CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
ELECTRIC COMMUNICATION TECHNIQUE
ELECTRICITY
GENERATION
TELEPHONIC COMMUNICATION
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Zusammenfassung:A circuit (1) for developing an AC ringing voltage from a PBX DC line voltage supply applied across a positive main terminal (2) and ground terminal (3) comprises a H-bridge circuit (8) which includes a bridge circuit (7) having four first transistors (Q1 to Q4) which are operated by four second transistors (Q5 to Q8) under the control of a microprocessor (20). The DC supply voltage is applied across input terminals (5,6) of the bridge circuit (7) through an input circuit (15) and an output circuit (17). The microprocessor (20) controls the operation of the second transistors (Q5 to Q8) for in turn selectively and alternately switching the first transistors (Q1 to Q4) in pairs, namely, (Q1 and Q2, and Q3 and Q4) for alternately reversing the voltage on output terminals (10,11) of the bridge circuit (7) for developing the AC ringing voltage for applying to a telephone (14) through an extension line (12). A detecting circuit comprising a first resistor (R8) and a second resistor (R3) facilitates detection of the on and off-hook state of the telephone (14) by the microprocessor (20).