Variable duty cycle swtiching circuit

Claim 2

A variable duty cycle switching circuit comprising, in combination, a saturable core transformer having first and second windings and a saturable core inductively coupling said windings, a pair of oppositely poled switching transistors having their emitter-collector paths connected in series across the opposite ends of said first winding and having their base electrodes connected to respective opposite ends of said second winding, impedance means comprising a third winding connected across the opposite ends of said first winding, D.C. supply means having one side connected to a point intermediate the ends of said third winding and its other side connected between the ends of said second winding and to the juncture between said emitter-collector paths of said transistors, said one side of said supply means also being connected to the base electrode of one transistor normally to forward bias same to conduct collector current and produce a voltage drop in one direction across said first winding through said impedance means, said first and second windings being of dot polarity first to reinforce the forward bias of said one transistor and then to reverse dot polarity to forward bias the other transistor whereby to initiate successive cycles of successive actuations of said transistors, control means connected to said one transistor normally preventing forward biasing of same, said control means including variable means for selectively varying the periodicity with which said one transistor is forward biased, and said variable means comprising a capacitor, a variable current source for charging said capacitor, and a dumping switch for said capacitor actuated in consonance with forward biasing of said other transistor.

Claim 3

The variable duty cycle switching circuit according to claim 1 wherein said impedance means comprises the primary winding of a transformer, said transformer having a secondary winding, and power switching means controlled by said secondary winding.

Claim 4

The variable duty cycle switching circuit according to claim 2 wherein said variable current source is controlled by said power switching means.

Claim 5

An electrical system comprising a load, a D.C. power supply for said load, and means for selectively varying the power supplied to said load, the improvement wherein: said means comprises a variable duty cycle switching circuit for controlling the connection of said power supply to said load, said variable duty cycle switching circuit including a saturable core transformer having first and second windings and a saturable core inductively coupling said windings, a pair of oppositely poled switching transistors having their emitter-collector paths connected in series across the opposite ends of said first winding and having their base electrodes connected to respective opposite ends of said second winding, impedance means comprising a third winding connected across the opposite ends of said first winding, one side of said power supply being connected to a point intermediate the ends of said third winding and the other side of said power supply being connected between the ends of said second winding and to the junction between the emitter-collector paths of said transistors, said one side of the power supply being also connected to the base electrode of one transistor normally to forward bias same to conduct collector current and produce a voltage drop in one direction across said first winding through said impedance means, said first and second windings being of dot polarity first to reinforce the forward biasing of said one transistor and then to reverse dot polarity to forward bias the other transistor whereby said switching circuit tends to operate in successive cycles of successive actuation of said transistors, and control means connected to said one transistor normally preventing forward biasing of same, said control means including variable means for selectively varying the periodicity with which said one transistor is forward biased by said power supply, said variable means comprising a capacitor, a variable current source for charging said capacitor, and a dumping switch for said capacitor actuated in consonance with forward biasing of said other transistor.

Claim 6

An electrical system comprising a load, a D.C. power supply for said load, and means for selectively varying the power supplied to said load, the improvement wherein: said means comprises a variable duty cycle switching circuit for controlling the connection of said power supply to said load, said variable duty cycle switching circuit including a saturable core transformer having first and second windings and a saturable core inductively coupling said windings, a pair of oppositely poled switching transistors having their emitter-collector paths connected in series across the opposite ends of said first winding and having their base electrodes connected to respective opposite ends of said second winding, impedance means comprising a third winding connected across the opposite ends of said first winding, one side of said power supply being connected to a point intermediate the ends of said third winding and the other side of said power supply being connected between the ends of said second winding and to the junction between the emitter-collector paths of said transistors, said one side of the power supply being also connected to the base electrode of one transistor normally to forward bias same to conduct collector current and produce a voltage drop in one direction across said first winding through said impedance means, said first and second windings being of dot polarity first to reinforce the forward biasing of said one transistor and then to reverse dot polarity to forward bias the other transistor whereby said switching circuit tends to operate in successive cycles of successive actuation of said transistors, and control means connected to said one transistor normally preventing forward biasing of same, said control means including variable means for selectively varying the periodicity with which said one transistor is forward biased by said power supply, said variable means comprising a capacitor, a variable current source for charging said capacitor, and a dumping switch for said capacitor actuated in consonance with forward biasing of said other transistor.

Claim 7

The electrical circuit according to claim 4 wherein said impedance means comprises the primary winding of a transformer, said transformer having a secondary winding, and power switching means controlled by said secondary winding.

Claim 8

The electrical circuit according to claim 5 wherein said variable current source is controlled by the output to said load.

Claim 9

An electrical system comprising a load, a D.C. power supply for said load, and means for selectively varying the power supplied to said load, the improvement wherein: said means comprises a variable duty cycle switching circuit for controlling the connection of said power supply to said load, said variable duty cycle switching circuit including a saturable core transformer having first and second windings and a saturable core inductively coupling said windings, a pair of oppositely poled switching transistors having their emitter-collector paths connected in series across the opposite ends of said first winding and having their base electrodes connected to respective opposite ends of said second winding, impedance means comprising a third winding connected across the opposite ends of said first winding, one side of said power supply being connected to a point intermediate the ends of said third winding and the other side of said power supply being connected between the ends of said second winding and to the junction between the emitter-collector paths of said transistors, said one side of the power supply being also connected to the base electrode of one transistor normally to forward bias same to conduct collector current and produce a voltage drop in one direction across said first winding through said impedance means, said first and second windings being of dot polarity first to reinforce the forward biasing of said one transistor and then to reverse dot polarity to forward bias the other transistor whereby said switching circuit tends to operate in successive cycles of successive actuation of said transistors, and control means connected to said one transistor normally preventing forward biasing of same, said control means including variable means fOr selectively varying the periodicity with which said one transistor is forward biased by said power supply, said load being an illuminating bulb and said power supply being nickel-cadmium battery means, and a protective circuit means responsive to the voltage of said battery means for abruptly decreasing the duty cycle of the switching circuit in the event that the voltage of the supply drops below a predetermined level.

Claim 10

An electrical system comprising a load, a D.C. power supply for said load, and means for selectively varying the power supplied to said load, the improvement wherein: said means comprises a variable duty cycle switching circuit for controlling the connection of said power supply to said load, said variable duty cycle switching circuit including a saturable core transformer having first and second windings and a saturable core inductively coupling said windings, a pair of oppositely poled switching transistors having their emitter-collector paths connected in series across the opposite ends of said first winding and having their base electrodes connected to respective opposite ends of said second winding, impedance means comprising a third winding connected across the opposite ends of said first winding, one side of said power supply being connected to a point intermediate the ends of said third winding and the other side of said power supply being connected between the ends of said second winding and to the junction between the emitter-collector paths of said transistors, said one side of the power supply being also connected to the base electrode of one transistor normally to forward bias same to conduct collector current and produce a voltage drop in one direction across said first winding through said impedance means, said first and second windings being of dot polarity first to reinforce the forward biasing of said one transistor and then to reverse dot polarity to forward bias the other transistor whereby said switching circuit tends to operate in successive cycles of successive actuation of said transistors, and control means connected to said one transistor normally preventing forward biasing of same, said control means including variable means fOr selectively varying the periodicity with which said one transistor is forward biased by said power supply, said load being an illuminating bulb and said power supply being nickel-cadmium battery means, and a protective circuit means responsive to the voltage of said battery means for abruptly decreasing the duty cycle of the switching circuit in the event that the voltage of the supply drops below a predetermined level.

Claim 11

The electrical circuit according to claim 7 wherein said protective circuit means includes means for periodically operating said switching circuit in maximum duty cycle pulse clusters.

Claim 12

The electrical circuit according to claim 8 wherein said variable means comprises a capacitor, a variable current source for charging said capacitor, and a dumping switch for said capacitor actuated in consonance with forward biasing of said other transistor.

Claim 13

The electrical circuit according to claim 9 wherein said impedance means comprises the primary winding of a transformer, said transformer having a secondary winding, and power switching means controlled by said secondary winding.

Claim 14

The electrical circuit according to claim 10 wherein said variable current source is controlled by the output to said load.

Claim 15

The electrical circuit according to claim 7 wherein said variable means comprises a capacitor, a variable current source for charging said capacitor, and a dumping switch for said capacitor actuated in consonance with forward biasing of said other transistor.

Claim 16

The electrical circuit according to claim 12 wherein said impedance means comprises the primary winding of a transformer, said transformer having a secondary winding, and power switching means controlled by said secondary winding.

Claim 17

The electrical circuit according to claim 13 wherein said variable current source is controlled by the output to said load.

Claim 18

The electrical circuit according to claim 7 wherein said impedance means comprises the primary winding of a transformer, said transformer having a secondary winding, and power switching means controlled by said secondary winding.

Claim 19

A variable duty cycle switching circuit comprising, in combination, a saturable core transformer having a first and second winding; a first normally open semiconductor switching device connected to one end of said second winding; a second normally open semiconductor switching device connected to the other end of said second winding; biasing means connected to both of said semiconductor devices, said first winding being connected at its opposite ends to respective ones of of said semiconductor devices whereby said biasing means tends to initiate successive cycles of successive actuation of said semiconductor switching devices; control means connected to said first semiconductor switching device normally preventing said biasing means from closing same, said control means including variable means for selectively varying the periodicity with which said first semiconductor switching device is permitted to close; said variable means comprising a capacitor, a variable current source for charging said capacitor, and a dumping switch for said capacitor actuated in consonance with closing of said second semiconductor switching device.

Claim 20

A variable duty cycle switching circuit comprising, in combination, a saturable core transformer having a first and second winding; a first normally open semiconductor switching device connected to one end of said second winding; a second normally open semiconductor switching device connected to the other end of said second winding; biasing means connected to both of said semiconductor devices, said first winding being connected at its opposite ends to respective ones of of said semiconductor devices whereby said biasing means tends to initiate successive cycles of successive actuation of said semiconductor switching devices; control means connected to said first semiconductor switching device normally preventing said biasing means from closing same, said control means including variable means for selectively varying the periodicity with which said first semiconductor switching device is permitted to close; said variable means comprising a capacitor, a variable current source for charging said capacitor, and a dumping switch for said capacitor actuated in consonance with closing of said second semiconductor switching device.