Browse Prior Art Database

Ring Generator

IP.com Disclosure Number: IPCOM000091589D
Original Publication Date: 1968-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Garcia, J: AUTHOR [+2]

Abstract

This power generator supplies ring service to a medium PBX of about 750 lines. It is a DC-to-AC converter energized from a 48V DC power supply. The ring generator mainly comprises an oscillator followed by a driving amplifier. An internal strap SP changes the ring frequency from 25 to 50 cps when required. Potentiometer PM, placed on the emitter of transistor T, allows for output level adjustment.

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Ring Generator

This power generator supplies ring service to a medium PBX of about 750 lines. It is a DC-to-AC converter energized from a 48V DC power supply. The ring generator mainly comprises an oscillator followed by a driving amplifier. An internal strap SP changes the ring frequency from 25 to 50 cps when required. Potentiometer PM, placed on the emitter of transistor T, allows for output level adjustment.

The signal from the Voltage Amplifier is applied to the Power Stage through transformer TR1. The output stage operates as a balanced push-pull. However, as current is required only during a half-wave, the circuit is asymmetrical. Three power transistors are in one leg and only one is in the other leg. The output transformer T2 has three primary windings and two secondary windings.

Primary winding P1 is connected to T1 and primaries P2 and P3 connect to transistors T2 and T3 respectively. Such an arrangement allows the current to be equally divided between T2 and T3. Main secondary winding S1, which delivers the ringing signals, is connected to ground through resistor R. The voltage developed on R makes thyristor TH conductive when the output current reaches the maximum overload level. TH operates as a threshold squeezer to prevent generator overload beyond a predetermined limit. Auxiliary secondary winding S2 is used to energize the switching relays. When connected to the PBX switching network, the ring generator is duplicated. In case of failure, an auto...