James A Adrian

US Patent:

40618846, Dec 6, 1977

Filed:

Aug 5, 1976

Appl. No.:

5/712012

Inventors:

James Mark Adrian - Naperville IL

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

International Classification:

H04Q 350

US Classification:

179 18GF

Abstract:

An arrangement for establishing communication paths through a plurality of serially connected thyristors comprising a first and last thyristor, is disclosed. Each thyristor comprises a main conduction path terminating in a first and second main conduction electrode and a control path between the first electrode and a gate electrode. The second main conduction electrode of each thyristor, except the last, is connected to the first main conduction electrode of a subsequent thyristor. To establish a path, a marking potential is applied to the first main conduction electrode of the first thyristor and gate currents, equal to or greater than the thyristor holding currents, are produced in the control paths of the thyristors in sequence and overlapped in time from the first to the last. A hold current is then produced in the second main conduction electrode of the last thyristor and the gate currents are terminated. Additionally, a gate current applied to a given thyristor can be terminated after the gate current of a succeeding device is flowing in the main conduction path of the given thyristor.

US Patent:

44291850, Jan 31, 1984

Filed:

Dec 21, 1981

Appl. No.:

6/332551

Inventors:

James M. Adrian - Naperville IL
Victor H. Mitnick - Lisle IL

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

International Classification:

H03K 1716
H04B 346
H04M 322

US Classification:

179 18FA

Abstract:

A voltage detector circuit for detecting a DC voltage on a line in the presence of a substantially fixed frequency AC voltage. The circuit may be used to detect call originations on a telephone line having longitudinal AC voltages induced thereon. The circuit compares the instantaneous voltage on the line with a reference level and repetitively increments a counter when the instantaneous voltage exceeds the reference level and repetitively decrements the counter when the instantaneous voltage does not exceed the reference level. After operating the counter for a time interval substantially equal to the period of the fixed frequency AC voltage, the most significant bit of the counter will indicate whether the DC voltage on the line is above the reference level. The circuit may also be used to detect call terminations on the line.