Combined bridge output and chopper circuit

Claim 2

A variable responsive D.C. bridge circuit comprising: a pair of D.C. voltage input terminals, a pair of resistance-containing branches extending between said voltage input terminals, there being associated with one of said branches variable responsive means for producing a variation in a voltage between a point coupled to an intermediate point of said one branch and constituting a first bridge output terminal and a point in common between said branches, a second bridge output terminal coupled to an intermediate point of the other branch circuit, a first output circuit terminal, and an output circuit coupled between said first and second bridge output terminals and including impedance means coupled between at least one of said bridge output terminals and said output circuit terminal, and a control voltage source whose output is to be superimposed on the output of the bridge circuit, a first capacitor connected between said output circuit terminal and said common point, said variable responsive voltage being coupled to said capacitor through said impedance means, and means coupling said control voltage source to said first capacitor so the capacitor charges to a voltage which is a function of both said variable responsive voltage and control voltage.

Claim 3

The variable responsive D.C. bridge control circuit of claim 1 wherein there is provided means for indicating the value of the variable comprising indicator means coupled between said bridge output terminals, and said impedance means isolating said one bridge output terminal from said output circuit terminal so the control voltage fed to said output circuit terminal has no effect on the indication of said indicator means.

Claim 4

The variable responsive D.C. bridge control circuit of claim 2 wherein said impedance means has a value such that variations in the control voltage at said output circuit terminal are not reflected back to said first bridge output terminal to which said indicator means is coupled.

Claim 5

The variable responsive D.C. bridge control circuit of claim 1 wherein said other branch circuit includes means for setting the initial voltage at said second bridge output terminal.

Claim 6

The variable responsive D.C. bridge control circuit of claim 4 wherein said control voltage source provides two component control voltages with respect to said common point at two output terminals thereof, a second output circuit terminal, second impedance meAns connected between said second bridge output terminal and said second output circuit terminal, a second capacitor coupled between said second output circuit terminal and said common point, means respectively connecting said output terminals of said control voltage source respectively to the terminals of said first and second capacitors remote from said common point, each of said first and second capacitors charging to a voltage which is a function both of the respective control voltage fed thereto and the voltage between the nearest bridge output terminal and said common point, said first impedance means between said first bridge output terminal and said first output circuit terminal and said second impedance means between said second bridge output terminal and said second output circuit terminal respectively isolating said bridge circuit output terminals from the voltage at said output circuit terminals, and switching means for alternately applying the voltages between said output circuit terminals and said common point to an external control circuit.

Claim 7

The variable responsive D.C. bridge control circuit of claim 5 wherein said switching means comprise a third capacitor a pair of switching devices with the corresponding load terminals thereof respectively coupled between said output circuit terminals and one terminal of a third capacitor whose other terminal is coupled to said common point the connections of the circuit to said external control circuit being from points across said third capacitor remote from said common point.

Claim 8

The variable responsive D.C. bridge control circuit of claim 6 wherein said switching means are field effect transistors whose conducting resistances are insignificant relative to said first and second impedance means.

Claim 9

A combined variable responsive D.C. bridge control and chopper circuit comprising: a pair of D.C. voltage input terminals, a pair of resistance-containing branches extending between said voltage input terminals, there being associated with one of said branches variable responsive means for producing a variation in the voltage with the variable value between an output point coupled to an intermediate point of said one branch which output point constitutes a first output terminal of the bridge circuit and a point in common between said branches, said bridge having a second output terminal connected to an intermediate point of said other branch; first and second capacitors respectively coupled between said bridge output terminals and said common point; means for coupling a control voltage to at least one of said capacitors so the voltage of said capacitor is a function of the control voltage and the voltage between the adjacent output terminal and said common point, the other capacitor charging to a voltage which is a function of the voltage between the other output terminal and said common point, a third capacitor having one plate connected to said common point, switch means for connecting the other plate of said third capacitor alternately and cyclically to the plate of said first and second capacitors remote from said common point, and means for coupling the voltages of said third capacitor to an external control circuit.

Claim 10

A combined variable responsive D.C. bridge control and chopper circuit comprising: a pair of D.C. voltage input terminals, a pair of resistance-containing branches extending between said voltage input terminals, there being associated with one of said branches variable responsive means for producing a variation in the voltage with the variable value between an output point coupled to an intermediate point of said one branch which output point constitutes a first output terminal of the bridge circuit and a point in common between said branches, said bridge having a second output terminal connected to an intermediate point of said other branch; first and second capacitors respectively coupled between said bridge output terminals and said common point; means for coupling a control voltage to at least one of said capacitors so the voltage of said capacitor is a function of the control voltage and the voltage between the adjacent output terminal and said common point, the other capacitor charging to a voltage which is a function of the voltage between the other output terminal and said common point, a third capacitor having one plate connected to said common point, switch means for connecting the other plate of said third capacitor alternately and cyclically to the plate of said first and second capacitors remote from said common point, and means for coupling the voltages of said third capacitor to an external control circuit.

Claim 11

In combination, a chopper circuit comprising first and second input terminals across which respectively are to be coupled separate variable D.C. voltages with respect to a common reference point, a pair of switch means having load terminals connected in series between said input terminals, a capacitor coupled between the juncture of said load terminals of said switch means and said common reference point, means for alternately rendering said switch means alternately conductive to couple said capacitor alternately to said first and second input terminals at a desired chopping rate, the time constant of the circuit including said capacitor between each of said input terminals and said common reference point being sufficiently short so the capacitor charges to the voltage applied between each Input terminal and said common reference point during the conducting period of the switch means involved, and means for coupling the voltage variation of said capacitor to a circuit external to the chopper circuit; and a bridge circuit having first and second output terminals respectively coupled to said first and second input terminals of said chopper circuit, said bridge circuit having a pair of D.C. energizing input terminals and a pair of resistance containing branches extending between said energizing voltage input terminals, there being associated with at least one of said branches variable responsive means for producing a variation in the voltage between a point associated with said one branch and constituting one of said bridge output terminals of the bridge circuit and a point in common with said branches, the other branch having a point associated therewith constituting the other bridge output terminal.

Claim 12

In combination, a chopper circuit comprising first and second input terminals across which respectively are to be coupled separate variable D.C. voltages with respect to a common reference point, a pair of switch means having load terminals connected in series between said input terminals, a capacitor coupled between the juncture of said load terminals of said switch means and said common reference point, means for alternately rendering said switch means alternately conductive to couple said capacitor alternately to said first and second input terminals at a desired chopping rate, the time constant of the circuit including said capacitor between each of said input terminals and said common reference point being sufficiently short so the capacitor charges to the voltage applied between each Input terminal and said common reference point during the conducting period of the switch means involved, and means for coupling the voltage variation of said capacitor to a circuit external to the chopper circuit; and a bridge circuit having first and second output terminals respectively coupled to said first and second input terminals of said chopper circuit, said bridge circuit having a pair of D.C. energizing input terminals and a pair of resistance containing branches extending between said energizing voltage input terminals, there being associated with at least one of said branches variable responsive means for producing a variation in the voltage between a point associated with said one branch and constituting one of said bridge output terminals of the bridge circuit and a point in common with said branches, the other branch having a point associated therewith constituting the other bridge output terminal.

Claim 13

The combination of claim 9 wherein said switch means are a pair of field effect transistors with the corresponding load terminals thereof respectively connected between said capacitor and the associated bridge output terminals, said means for rendering said switch means alternately conductive including means for feeding signals to the gate terminals of said field effect transistors for alternately rendering the same conductive and non-conductive.