Circuit arrangement for emitting ringing signals in a telephone

Details Circuit arrangement for emitting ringing signals in a telephone Circuit arrangement for emitting ringing signals in a telephone

1981-02-18

1982-12-07

Brown, Thomas W.

179 84A, H04M 302

Patent

active

043629083

ABSTRACT:
A circuit arrangement for emitting ringing signals to a subscriber station in response to a call signal electronically generated at a telephone exchange comprises a control unit which, in the presence of such call signal, intermittently reverses a switching relay normally connecting the talking conductors of the subscriber line to monitoring equipment of the exchange whereby these conductors periodically receive a high-voltage ringing current, e.g. of 25 Hz, from a local oscillator in series with a d-c supply. The direct current is blocked by a line-terminating capacitor until the called subscriber lifts the receiver off the hook to close the line loop. If this occurs while the line is connected to the oscillator, a sensor in the control unit detects a significant disparity between the durations of the positive and negative voltage swings in an oscillator cycle and causes the release of the switching relay when that disparity exceeds a dynamic threshold determined by the actual cycle length.

REFERENCES:
patent: 3720793 (1973-03-01), Hofmann
patent: 3941939 (1976-03-01), Holmes et al.
patent: 3978293 (1976-08-01), Feiner
patent: 4087646 (1978-05-01), Brolin et al.
patent: 4262172 (1981-04-01), Brolin
"A New Electronic Ring-Trip Circuit", by Katsumi and Ariizumi, Review of the Electrical Communication Laboratory, vol. 19, Nos. 1-2, Jan.-Feb. 1971, pp. 37-43.

Affiliated with

Also associated with

Rating

Circuit arrangement for emitting ringing signals in a telephone does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Circuit arrangement for emitting ringing signals in a telephone , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit arrangement for emitting ringing signals in a telephone will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1904532