Current limiting power supply

Claim 2

A power supply for regulating a current to provide current of a predetermined maximum level comprising: a pair of output terminals for connecting a load; a pair of input terminals for receiving a source current, a first one of said pair of input terminals electrically connected to a first one of said pair of output terminals; switch means connected to a second one of said pair of input terminals, said switch means selectively actuable for establishing either a conductive or a nonconductive connection through said switch to said input terminal; a filter Network connected to said pair of output terminals for smoothing DC pulses to a continuous current flow; a diode connected to said first output terminal; a transformer having a center-tapped primary winding and a secondary winding, said primary winding connected between said switch means and said diode, said center-tap connected to said filter network, said primary winding inducing a voltage in said secondary winding proportional to the flow of current in said primary winding; and a bistable device coupled to said secondary winding of said transformer and responsive to the output voltage thereon for switching to a first stable state whenever the output current rises above a predetermined level and for switching to a second stable state whenever the output current falls below a predetermined level, said bistable device actuating said switch means to establish a conductive connection whenever it switches to one of its stable states and said bistable device actuating said switch means to establish a nonconductive connection whenever it switches to the other of its stable states.

Claim 3

A combination as defined in claim 1 wherein said filter network for smoothing DC pulses includes an inductance connected at one end to said second output terminal and a capacitance connected between said pair of output terminals, said center tap of said transformer being connected to the other end of said inductance.

Claim 4

The combination as defined in claim 1 wherein said filter network includes an inductance connected at one end to said second output terminal and a capacitance connected between the other end of said inductance and said first output terminal, said center tap of said transformer being connected to the junction of said inductance and said capacitance.

Claim 5

The combination as defined in claim 1 and further comprising an amplifier connected between said second output terminal and said bistable device and responsive to the output current for switching said bistable device from one of its stable states to the other when an instantaneous overload occurs in the output current.

Claim 6

A power supply for regulating a current and voltage to provide a DC output current of predetermined maximum level and a DC output voltage of predetermined voltage level comprising: a pair of output terminals for supplying an output voltage and current to a load; a pair of input terminals for receiving a source voltage and current, a first one of said pair of input terminals electrically connected to a first one of said pair of output terminals; switch means connected to a second one of said pair of input terminals, said switch means selectively actuatable for establishing either a conductive or a nonconductive connection through said switch in said second input terminal; a filter network connected to said pair of output terminals for smoothing unidirectional voltage pulses, into a substantially constant output voltage, said filter network comprising an inductance connected to said second output terminal and a capacitor connected to said inductance and to said first output terminal; a diode connected to said first output terminal; a transformer having a center-tapped primary winding and a secondary winding, said primary winding connected between said switch means and said diode, said center tap connected to said inductance, said primary winding inducing a voltage in said secondary winding proportional to the flow of current in said primary winding; means for producing a reference voltage; a first bistable device coupled to receive the reference voltage and the output voltage for producing a first error signal whenever the output voltage falls below the reference voltage and for producing a second error signal whenever the output voltage rises above the reference voltage; means responsive to the first error signal for actuating said switch means to establish a conductive connection ad responsive to the second error signal for actuating said switch meAns to establish a nonconductive connection; rectifying means coupled to the secondary winding of said transformer responsive to the induced voltage thereon for producing a DC voltage proportional to the flow of current in the primary winding of said transformer; a second bistable device coupled to said rectifying means for switching to a first stable state whenever the output current rises above a predetermined level and for switching to a second stable state whenever the output current falls below a predetermined level, said second bistable device connected to said first bistable device for actuating said first bistable device to produce said first error signal whenever the output current falls below said predetermined level and for producing said second error signal whenever the output current rises above said predetermined level.

Claim 7

A power supply for regulating a current and voltage to provide a DC output current of predetermined maximum level and a DC output voltage of predetermined voltage level comprising: a pair of output terminals for supplying an output voltage and current to a load; a pair of input terminals for receiving a source voltage and current, a first one of said pair of input terminals electrically connected to a first one of said pair of output terminals; switch means connected to a second one of said pair of input terminals, said switch means selectively actuatable for establishing either a conductive or a nonconductive connection through said switch in said second input terminal; a filter network connected to said pair of output terminals for smoothing unidirectional voltage pulses, into a substantially constant output voltage, said filter network comprising an inductance connected to said second output terminal and a capacitor connected to said inductance and to said first output terminal; a diode connected to said first output terminal; a transformer having a center-tapped primary winding and a secondary winding, said primary winding connected between said switch means and said diode, said center tap connected to said inductance, said primary winding inducing a voltage in said secondary winding proportional to the flow of current in said primary winding; means for producing a reference voltage; a first bistable device coupled to receive the reference voltage and the output voltage for producing a first error signal whenever the output voltage falls below the reference voltage and for producing a second error signal whenever the output voltage rises above the reference voltage; means responsive to the first error signal for actuating said switch means to establish a conductive connection ad responsive to the second error signal for actuating said switch meAns to establish a nonconductive connection; rectifying means coupled to the secondary winding of said transformer responsive to the induced voltage thereon for producing a DC voltage proportional to the flow of current in the primary winding of said transformer; a second bistable device coupled to said rectifying means for switching to a first stable state whenever the output current rises above a predetermined level and for switching to a second stable state whenever the output current falls below a predetermined level, said second bistable device connected to said first bistable device for actuating said first bistable device to produce said first error signal whenever the output current falls below said predetermined level and for producing said second error signal whenever the output current rises above said predetermined level.

Claim 8

The combination as defined in claim 5 and further comprising: an amplifier connected between said second output terminal and said second bistable device for switching said second bistable device from one of the stable states to the other whenever on instantaneous overload occurs in the output current.