Threshold circuit for tone-ringer or like load means

Abstract

Abstract 1. A THRESHOLD CIRCUIT FOR ENERGIZING FROM A D.C. POWER SUPPLY SOURCE A FIRST LOAD MEANS HAVING FIRST AND SECOND TERMINALS, SAID CIRCUIT COMPRISING A DUMMY LOAD SWITCHABLY INTERCONNECTED ACROSS THIRD AND FOURTH TERMINALS FOR CONNECTION TO SAID POWER SUPPLY SOURCE WHEN SAID LOAD MEANS IS DISCONNECTED THEREFROM, SAID DUMMY LOAD HAVING FIFTH AND SIXTH TERMINALS AND ADAPTED TO DRAW LESS CURRENT THAN SAID FIRST LOAD MEANS, WHEREBY THE POTENTIAL DIFFERENCE BETWEEN SAID THIRD AND FOURTH TERMINALS IS GREATER BY A VALUE V1 WITH SAID DUMMY LOAD OPERATIVELY CONNECTED THEREBETWEEN THAN WITH SAID FIRST LOAD MEANS SO CONNECTED FOR A GIVEN POWER SUPPLY IMPEDANCE, SAID FIFTH TERMINAL CONNECTED TO SAID FOURTH TERMINAL OF SAID POWER SUPPLY SOURCE AND SAID SIXTH TERMINAL CONNECTED THROUGH A FIRST CONTROLLABLE SWITCH MEANS TO THE CONTROL ELEMENT OF A SECOND CONTROLLABLE SWITCH MEANS, THE CONTROL ELEMENT OF SAID FIRST CONTROLLABLE SWITCH MEANS CONNECTED THROUGH SAID SECOND CONTROLLABLE SWITCH MEANS TO SAID THIRD TERMINAL, A FOURTH CONTROLLABLE SWITCH MEANS BETWEEN SAID FIRST TERMINAL OF SAID FIRST LOAD MEANS AND SAID THIRD TER MINAL, THE CONTROL ELEMENT OF SAID FOURTH CONTROLLABLE SWITCH MEANS CONNECTED TO THE CONTROL ELEMENT OF SAID FIRST CONTROLLABLE SWITCH MEANS AND THROUGH A THIRD CONTROLLABLE SWITC MEANS TO SAID FOURTH TERMINAL, VOLTAGE THRESHOLD MEANS COMPRISING FIRST AND SECOND SERIES CONNECTED PORTIONS THEREOF AND HAVING A THRESHOLD VALUE V2, CONNECTED BETWEEN SAID THIRD TERMINAL AND THE CONTROL ELEMENT OF SAID THIRD CONTROLLABLE SWITCH MEANS, SAID SECOND PORTION BEING CONNECTED TO SAID CONTROL ELEMENT OF SAID THIRD CONTROLLABLE SWITCH MEANS, AND UNIDIRECTIONAL CURRENT PASSING MEANS CONNECTING THE JUNCTION BETWEEN SAID FIRST AND SECOND PORTIONS OF SAID THRESHOLD MEANS TO SAID FIRST TERMINAL OF SAID FIRST LOAD MEANS AND ADAPTED TO BLOCK CURRENT FLOW BETWEEN SAID FIRST TERMINAL OF SAID FIRST LOAD MEANS AND SAID THIRD TERMINAL WHEN SAID FOURTH CONTROLLABLE SWITCH MEANS IS DISABLED, SAID SECOND TERMINAL OF SAID FIRST LOAD MEANS BEING CONNECTED TO SAID FOURTH TERMINAL, WHEREBY A CURRENT PATH IS ESTABLISHED BETWEEN SAID THIRD TERMINAL AND SAID CONTROL ELEMENT OF SAID THIRD CONTROLLABLE SWITCH MEANS ENABLING SAID THIRD CONTROLLABLE SWITCH MEANS WHEN THE POTENTIAL DIFFERENCE BETWEEN SAID THIRD AND FOURTH TERMINALS REACHES SAID THRESHOLD VALUE V2, THE BREAKDOWN VOLTAGES OF SAID UNDIRECTIONAL CURRENT PASSING MEANS AND SAID SECOND PORTION OF SAID THRESHOLD MEANS BEING SUCH AS TO PASS ENABLING CURRENT TO THE CONTROL ELEMENT OF SAID THIRD CONTROLLABLE SWITCH MEANS WHEN SAID FOURTH CONTROLLABLE SWITCH MEANS IS ENABLED AND THE POTENTIAL DIFFERENCE BETWEEN SAID THIRD AND FOURTH TERMINALS IS WITHIN THE RANGE OF VALUES FROM (V2-V1) OR LOWER TO V2.

Inventors

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