Adaptive transistor switch

Claim 2

An improved semiconductor switching circuit for controlling electrical current through a variable load, comprising a. semiconductor means having first, second and control electrodes with said first and second electrodes adapted to be connected to the variable load and a suitable supply so as to control electrical current flowing through the variable load, and b. circuit means connected to the control electrode of said semiconductor means for controlling the current through said control electrode in response to variations of the variable load to tend to maintain a forced beta substantially constant for said semiconductor means.

Claim 3

An improved semiconductor switching circuit as set forth in claim 1 wherein the semiconductor means includes a transistor and the control electrode is a base electrode of said transistor.

Claim 4

An improved semiconductor switching circuit for controlling electrical current through a variable load, comprising a. transistor means having a base, an emitter and a collector and adapted to be connected to the variable load and a suitable supply so as to control electrical current flowing through the variable load, and b. circuit means connected to the base of said transistor means for controlling base current in response to variations of the variable load to maintain a forced beta substantially constant for said transistor means.

Claim 5

An improved semiconductor switching circuit for controlling electrical current through a variable load, comprising a. transistor means having a base, an emitter and a collector and adapted to be connected to the variable load and a suitable supply so as to control electrical current flowing through the variable load, and b. circuit means connected to the base of said transistor means for controlling base current in response to variations of the variable load to maintain a forced beta substantially constant for said transistor means.

Claim 6

An improved semiconductor switching circuit as set forth in claim 3 wherein the circuit means includes circuitry sensitive to a voltage change across at least part of said transistor means, said voltage sensitive circuitry being connected to said circuit means for limiting the current flowing from the base of said transistor means through said circuit means.

Claim 7

An improved semiconductor switching circuit for controlling electrical current through a variable load, comprising: a. transistor means having a base, an emitter and a collector and adapted to be connected to the variable load and a suitable supply so that collector current flows through the variable load; b. circuit means connected to the base of said transistor means providing a base current path with a variable characteristic for varying the amount of base current flow in response to variation of said characteristic; and c. said circuit means further being connected to said transistor means for sensing a voltage drop across at least a portion of said transistor means which is proportional to collector current therethrough and for controlling said variable characteristic in response to changes in said voltage drop to tend to maintain a constant ratio between the colLector and base current of said transistor means.

Claim 8

An improved semiconductor switching circuit for controlling electrical current through a variable load, comprising: a. transistor means having a base, an emitter and a collector and adapted to be connected to the variable load and a suitable supply so that collector current flows through the variable load; b. circuit means connected to the base of said transistor means providing a base current path with a variable characteristic for varying the amount of base current flow in response to variation of said characteristic; and c. said circuit means further being connected to said transistor means for sensing a voltage drop across at least a portion of said transistor means which is proportional to collector current therethrough and for controlling said variable characteristic in response to changes in said voltage drop to tend to maintain a constant ratio between the colLector and base current of said transistor means.

Claim 9

An improved semiconductor switching circuit as set forth in claim 5 wherein the circuit means includes a semiconductor device and the variable characteristic is the conduction of current therethrough.

Claim 10

An improved semiconductor switching circuit as set forth in claim 5 wherein the circuit means includes a semiconductor device for sensing variations in the voltage drop across at least a portion of said transistor means, said semiconductor device having at least one junction connected in parallel with at least one junction of said transistor means and constructed to allow a flow of current therethrough proportional to the flow of current through said one junction of said transistor means.

Claim 11

An improved method of controlling electrical current through a variable load, comprising the steps of: a. connecting a transistor means to said load and to a suitable current source so that load current flows through said transistor means; b. sensing current flow in said transistor means; and c. controlling base current in said transistor means in response to said load current flow therethrough for maintaining the forced beta of said transistor means substantially constant.

Claim 12

An improved method of controlling electrical current through a variable load, comprising the steps of: a. connecting a transistor means to said load and to a suitable current source so that load current flows through said transistor means; b. sensing current flow in said transistor means; and c. controlling base current in said transistor means in response to said load current flow therethrough for maintaining the forced beta of said transistor means substantially constant.