Constant current variable load regulator

Claim 2

A continuously variable electric load for maintaining a constant current drain from a power supply, said load comprising: a pair of input terminals adapted to be connected to a power supply; a variable impedance connected between said terminals for maintaining a predetermined level of load current; means for sensing current connected to said variable impedance for sensing the level of current flowing through said variable impedance means and for developing a signal indicative of said level of the load current; control means connected to said means for sensing current to receive said signal, and connected to said variable impedance, said control means being responsive to said signal to regulate the impedance of said variable impedance to maintain a predetermined load current level; and means for supplying electrical power to said control means.

Claim 3

The combination accordiNg to claim 1 and further comprising a second variable impedance and a resistor connected in series between said input terminals to divide the load current between said variable impedances, said control means being connected to both said variable impedances.

Claim 4

The combination according to claim 1 further comprising a plurality of circuits connected between said input terminals to divide the load current, each said circuit comprising a variable impedance and a resistor connected in series, said control means being connected to each said variable impedance to regulate a predetermined current level through each said variable impedance.

Claim 5

The combination according to claim 1 wherein said control means includes an input network for receiving an AC signal, said variable impedance being responsive to said control means to vary the load current in accordance with the AC signal.

Claim 6

The combination according to claim 1 wherein said control means includes a difference amplifier.

Claim 7

The combination according to claim 5 and further comprising a Zener diode and a voltage divider network connected in series between said input terminals and a bistable device connected between said voltage divider network and said difference amplifier for switching to a first stable state whenever the input voltage falls below a predetermined level and for switching to a second stable state whenever the input voltage rises above the predetermined level, said difference amplifier being responsive to said bistable device to reduce the load current by a predetermined scale factor whenever the input voltage rises above the predetermined voltage level.

Claim 8

The combination according to claim 6 and further comprising a Zener diode and a resistor connected in series between the junction of said first-mentioned Zener diode and said voltage divider network and said input terminal, and further including a second resistor connected to the junction of said second Zener diode and said first resistor and said difference amplifier, said difference amplifier being responsive to the input voltage to switch the load current to substantially zero when said input voltage rises above a predetermined voltage level.

Claim 9

The combination according to claim 1 wherein said variable impedance is a transistor and said means for sensing current includes a resistor connected in series with said transistor between said input terminals.

Claim 10

A continuously variable electrical load comprising: a pair of input terminals; at least one transistor connected to a first one of said terminals for maintaining a predetermined level of load current; a current-sensing resistor connected in series between said transistor and a second one of said input terminals for developing a signal indicative of the load current level; means for supplying electrical power; a difference amplifier having a pair of inputs connected to said means for supplying electrical power, said difference amplifier including a pair of bias networks, a first bias network connected in series between said means for supplying electrical power and said sensing resistor, said first biasing network including at least one variable resistor for adjusting the load current to a predetermined level, a first input of said pair of inputs to said difference amplifier connected to said first bias network to receive a signal indicative of the difference between the actual load current and the predetermined level of load current, said second bias network connected to said power supply to establish a reference voltage, said second bias network having at least one variable resistor for setting a predetermined maximum level of load current, a second one of said pair of inputs of said difference amplifier connected to said second bias network to receive a reference voltage corresponding to the predetermined maximum level of load current; and means for coupling the output signal from said difference amplifier to said transistor for Maintaining the load current level through said transistor at the predetermined level.

Claim 11

A continuously variable electrical load comprising: a pair of input terminals; at least one transistor connected to a first one of said terminals for maintaining a predetermined level of load current; a current-sensing resistor connected in series between said transistor and a second one of said input terminals for developing a signal indicative of the load current level; means for supplying electrical power; a difference amplifier having a pair of inputs connected to said means for supplying electrical power, said difference amplifier including a pair of bias networks, a first bias network connected in series between said means for supplying electrical power and said sensing resistor, said first biasing network including at least one variable resistor for adjusting the load current to a predetermined level, a first input of said pair of inputs to said difference amplifier connected to said first bias network to receive a signal indicative of the difference between the actual load current and the predetermined level of load current, said second bias network connected to said power supply to establish a reference voltage, said second bias network having at least one variable resistor for setting a predetermined maximum level of load current, a second one of said pair of inputs of said difference amplifier connected to said second bias network to receive a reference voltage corresponding to the predetermined maximum level of load current; and means for coupling the output signal from said difference amplifier to said transistor for Maintaining the load current level through said transistor at the predetermined level.

Claim 12

The combination according to claim 9 comprising: a plurality of transistors connected to a first one of said terminals for maintaining a predetermined level of load current, each of said transistors having a current-sensing resistor connected in series with a second one of said input terminals, at least one of said current-sensing resistors developing a signal indicative of the load current level, said coupling means coupling the output signal from said difference amplifier to each of said transistors for maintaining the load current level through each said transistor at the predetermined level.