Single element adjustment for span and gain

Claim 2

An adjustable span null balance system responsive to an input signal comprising: an amplifier having an input terminal and a common terminal, means for producing a first feedback signal related to the output of said amplifier, means for producing a second feedback signal related to the output of the system, means for summing said first and second feedback signals, and a single adjustable resistance having a pair of fixed terminals and an adjustable terminal, said amplifier common terminal being connected to one of said fixed terminals, the summed feedback signals being applied to the other of said fixed tErminals, and said input signal being applied between said adjustable terminal and said input terminal so that a change in said adjustable resistance changes both the span of said system and the gain of said amplifier without changing the sensitivity of the system.

Claim 3

The system recited in claim 1 wherein said second feedback signal is a balancing voltage, and wherein said means for producing a second feedback signal related to the output of the system includes a potentiometer having an adjustable slidewire for developing said balancing voltage in opposition to said input signal and of a magnitude variable by adjustment of said slidewire, and means responsive to the output of said amplifier for adjusting the position of said slidewire.

Claim 4

The system recited in claim 2 wherein said null balance system is included in a strip-chart recorder for recording the magnitude of said input signal, said recorder including a marking means, said means responsive to the output of said amplifier being connected to drive said marking means on said strip-chart concurrent with the positioning of said slidewire.

Claim 5

The system recited in claim 1 wherein said system is a measuring system further comprising a dynamic sub-system having a time constant which is large compared to the effective time constant of said system, said sub-system being connected between the output of said amplifier and the output of said system.

Claim 6

The system recited in claim 1 wherein said system is a measuring system further comprising a dynamic sub-system having an output response which is non-linear with respect to its input, the output of said amplifier being connected to the input of said sub-system, the output of said sub-system being the output of said system.

Claim 7

The system recited in claim 1 wherein said adjustable resistance is a potentiometer having an adjustable slidewire and wherein said input signal is an input voltage, said input voltage being applied to said adjustable slidewire, said potentiometer being connected between said means for summing said first and second feedback signals and an input of said amplifier.

Claim 8

The system recited in claim 1 wherein said means for producing a second feedback signal includes an amplifier producing a feedback voltage, said feedback voltage being applied to said single adjustable resistance.

Claim 9

The system recited in claim 1 wherein said means for producing a second feedback signal includes an operational amplifier producing a feedback current output, said feedback current being supplied to said single adjustable resistance.

Claim 10

An adjustable span null balance system responsive to an input signal wherein a single element is used for simultaneous adjustment of span and gain, said system comprising: a linear pre-amplifier having a pair of inputs and an output, said input signal being applied to said inputs with one of said inputs connected and referenced to circuit common, circuit means connected to the output of said pre-amplifier, said circuit means including an additional amplifier for producing a system output, said circuit means also including means for producing a feedback signal related to said system output, additional circuit means for combining said feedback signal and a signal related to the output of said pre-amplifier, and a single adjustable element having an adjustable terminal, said adjustable element being inserted and connected between said additional circuit means and circuit common for inserting a selected portion of said summed signal, said input signal being applied between the other of said pair of inputs and said adjustable terminal whereby said pre-amplifier is responsive to the difference between said input signal and said selected portion of said combined signal thus achieving simultaneous adjustment of said span and gain by said single adjustable element.

Claim 11

An adjustable span null balance system responsive to an input signal wherein a single element is used for simultaneous adjustment of span and gain, said system comprising: a linear pre-amplifier having a pair of inputs and an output, said input signal being applied to said inputs with one of said inputs connected and referenced to circuit common, circuit means connected to the output of said pre-amplifier, said circuit means including an additional amplifier for producing a system output, said circuit means also including means for producing a feedback signal related to said system output, additional circuit means for combining said feedback signal and a signal related to the output of said pre-amplifier, and a single adjustable element having an adjustable terminal, said adjustable element being inserted and connected between said additional circuit means and circuit common for inserting a selected portion of said summed signal, said input signal being applied between the other of said pair of inputs and said adjustable terminal whereby said pre-amplifier is responsive to the difference between said input signal and said selected portion of said combined signal thus achieving simultaneous adjustment of said span and gain by said single adjustable element.