US 3,943,415 AGranted

Timing circuit

OwnerJames P. Minearinventor

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Abstract

A timing circuit is disclosed which utilizes a principal transistor as a switch to control current flow through a load. The emitter and collector of this principal transistor are connected in a series with a load across DC terminals. Two control transistors are used to regulate when a current is passed by the principal transistor. The base of a first of these control transistors is connected between a resistor and a capacitor in an RC circuit which is connected so as to determine if a current is flowing in the first mentioned series circuit. The base of the other of the transistors is connected to the first mentioned series circuit through a resistor and a capacitor and is grounded through a resistor. As a result of charging of its associated capacitor and of feedback through this capacitor the first control transistor serves to render the principal transistor conductive after it has not conducted a current for a time interval determined by its associated resistor. The second control transistor serves to maintain the principal transistor conductive as its associated capacitor becomes charged and as the charge bleeds off of it.

Claims9

Dependent claims

A timing circuit for use in supplying an electric current to a load, said current flowing between two terminals when it is supplied to said load in which the improvement comprises:

switch means for passing said current at repetitive periods, said switch means being connected in a series circuit with said load between said terminals, said switch means being capable of being electrically controlled,
switch control means for use in controlling the operation of said switch means so as to permit a current to flow between said terminals as repetitive periods, said switch control means being connected to said switch means,
first current flow responsive means for actuating said switch control means at a time interval after no current has flowed between said terminals so as to permit current to flow through said switch means, said first current flow responsive means being connected to said switch control means and being connected to said series circuit, said first current flow responsive means being capable of being actuated by current flowing between said terminals when current is not flowing in said series circuit, said first current flow responsive means being responsive to the flow of current in said series circuit so as to no longer actuate said switch control means to cause said switch control means to control said switch means so that said switch means passes a current,
other current flow responsive means connected to said switch control means and to said series circuit for causing said switch control means to maintain said switch means capable of passing a current for a time interval after said switch means has commenced passing a current as the result of the action of said first current flow responsive means.

1 more element

Dependencies are inferred from the claim text.