Gas pressure measuring circuit
OwnerAlan E. Holmeinventor
Life of this patent
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Abstract
In a circuit for controlling the temperature of a filament in a Pirani gauge head, secondary temperature compensation is provided by mounting an auxiliary resistor adjacent the temperature-compensating arm of a bridge. The auxiliary resistor forms part of a potential divider which provides a preset offset voltage to an associated output amplifier. This offset voltage is added algebraically to the variable voltage driving the bridge circuit so as to provide additional temperature compensation.
Claims8
A circuit for operating a Pirani gauge comprising,
- an electrical bridge which has one arm adapted to receive the gauge and which is arranged to produce an electrical output signal representative of gas pressure within the gauge,
- a temperature-sensitive resistive device in an arm of the bridge for providing temperature compensation of the output of the bridge,
- temperature sensing electrical means not embodied within an arm of the bridge and effective to produce an electrical signal indicative of the ambient temperature in which the gauge operates, and
- signal translation means electrically connected to and responsive to the output of the bridge and to the signal from the electrical means and capable of producing a gas pressure signal compensated for ambient temperature changes.
A circuit as claimed in any preceding claim wherein both resistive elements are proximate.
A circuit for operating a Pirani gauge comprising,
- an electrical bridge which has one arm adapted to receive the gauge and which is arranged to produce an electrical output signal representative of gas pressure within the gauge,
- a temperature-sensitive resistive device in an arm of the bridge for providing temperature compensation of the output of the bridge,
- a potential divider, comprising a tap and a temperature sensitive resistive device, not embodied within an arm of the bridge and effective to produce from a potential difference applied across the divider a signal indicative of the ambient temperature in which the gauge operates, and
- an amplifier responsive to the output of the bridge and to the signal from the tap and capable of producing a gas pressure signal compensated for ambient temperature changes.
Dependencies are inferred from the claim text.