CONTROL CIRCUIT HAVING LOAD AND POWER SOURCE ISOLATION

• US 3,800,185 A
• Filed: 09/15/1972
• Issued: 03/26/1974
• Est. Priority Date: 09/15/1972
• Status: Expired due to Term

• Current Assignee: John E. Collins, Peter A. Lind, William J.E. Anton
• Original Assignee: John E. Collins, Peter A. Lind, William J.E. Anton
• Inventors: Anton, William J. E., Lind, Peter A., Collins, John E.
• Primary Examiner(s): Demeo, Palmer C.
• Application Number:
  US05/289,444
• Time in Patent Office: 557 Days
• Field of Search: 315/149,153,156,159,250,297,320,201 340/41R
• US Class Current: 315/153
• CPC Class Codes: G08G 1/095 Traffic lights

Abstract

A single proportional type control unit having a gated semiconductor switching device controlled by a single condition responsive impedance can be connected to one or more loads or to one or more power sources. Diodes are arranged to provide load and power source isolation. The circuit, for example, is connected in a traffic light control system to control the intensity of more than one lamp in a single traffic signal face for a traffic phase having more than one traffic signal face. One circuit provides control of the intensity of the lamps for onehalf of each cycle of the A.C. source connected to the control circuit. A modified circuit provides full cycle control of the lamps connected to the control circuit. The condition responsive impedance for such use is light responsive.

Claims

1. A circuit for connection in a traffic control system between one or more lamps of a traffic signal face in a traffic phase having one or more traffic signal faces and the common neutral of the traffic control system to control the degree of current flow to the connected lamps in accordance with background illumination comprising:

a circuit portion including a gated semiconductor switching device for controlling current flow through said circuit portion and a gating circuit having a background illumination responsive device connected to gate said switching device; and

a plurality of sets of two, like poled, series connected, unidirectional devices, one set for each lamp to be controlled, said sets poled in the same direction and connected in parallel across said circuit portion, each of said sets providing a separate connecting point for a lamp to be controlled, said connecting point being intermediate the two unidirectional devices of the set.

2. A circuit for connection in a traffic control system between one or more lamps of a traffic signal face in a traffic phase having one or more traffic signal faces and the common neutral of the traffic control system to control the degree of current flow to the connected lamps in accordance with background illumination comprising:

a circuit portion including a gated semiconductor switching device for controlling current flow through said circuit portion and a gating circuit having a background illumination responsive device connected to gate said switching device; and

a plurality of sets of two, like poled, series connected, unidirectional devices, one set for each lamp plus another set, said sets poled in the same direction and connected in parallel across said circuit portion;

each of said sets providing a connecting point for the control circuit, said connecting point for each set being intermediate the two unidirectional devices of the set, said connecting point of said another set providing a connecting point for connection to the common neutral of the traffic signal system with the remaining connecting points being lamp connecting points for the control circuit.