Voltage regulators for use in battery charging systems

Claim 2

A voltage regulator for use in a battery charging system, including an input transistor, an output transistor which in use controls current floW in the field winding of a generator charging a battery, means coupling the input and output transistors whereby the input transistor controls conduction of the output transistor, a resistance chain for sensing the output voltage of the generator in use a Zener diode connected to the resistance chain so asto conduct at a predetermined voltage, the Zener diode controlling conduction of the input transistor, said resistance chain including a thermistor for providing temperature compensation, and the thermistor being bridged by the collectoremitter path of a further transistor, the regulator further including biasing means responsive to said thermistor for controlling the base voltage of said further transistor so that the regulated voltage varies with temperature in a predetermined manner.

Claim 3

A regulator as claimed in claim 4 in which said biasing means turns the transistor on when the thermistor is relatively cold, so that it has a relatively high resistance value, but when the thermistor is relatively hot and has a relatively low resistance value, the transistor is substantially non-conductive so that most of the current flows through the thermistor.

Claim 4

A regulator as claimed in claim 4 in which the Zener diode controls the conduction of an input transistor which when conductive removes base current from the output transistor, the input and output transistors being interconnected by a positive feedback circuit so that the transistors oscillate between one state in which the input transistor is fully conductive and the output transistor is off, and another state in which the output transistor is fully conductive and the input transistor is off, the mark-space ratio being determined by the current flowing through the Zener diode.

Claim 5

A voltage regulator for use in a battery charging system, including an output transistor which in use controls current flow in the field winding of a generator charging a battery, a resistance chain for sensing the output voltage of the generator in use, a Zener diode connected to the resistance chain so as to conduct at a predetermined voltage, the Zener diode controlling conduction of the output transistor, said resistance chain including a thermistor for providing temperature compensation, and the thermistor being bridged by two parallel paths, the first of which contains the emitter-collector of a further transistor, and the second of which contains first and second resistors in series, the junction of said first and second resistors being connected to the base of said further transistor, and the first and second resistors serving to control the voltage of the base of said further transistor so that the regulated voltage varies with temperature in a predetermined manner.

Claim 6

A voltage regulator for use in a battery charging system, including an output transistor which in use controls current flow in the field winding of a generator charging a battery, a resistance chain for sensing the output voltage of the generator in use, a Zener diode connected to the resistance chain so as to conduct at a predetermined voltage, the Zener diode controlling conduction of the output transistor, said resistance chain including a thermistor for providing temperature compensation, and the thermistor being bridged by two parallel paths, the first of which contains the emitter-collector of a further transistor, and the second of which contains first and second resistors in series, the junction of said first and second resistors being connected to the base of said further transistor, and the first and second resistors serving to control the voltage of the base of said further transistor so that the regulated voltage varies with temperature in a predetermined manner.