Importance

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Abstract

A fluid flow sensor especially adapted for use in solid state electronic system. The sensor employs a heated thermistor in a first sensing network with a temperature compensation means, the two being connected in common to a sensor point. A second network includes a threshold adjusting means and a diode power supply fluctation circuit connected to a threshold point. The two networks are connected in a bridge circuit across a power supply. The thermistor responds to temperature changes associated with air flow changes to produce a change in circuit condition at the sensor point relative to the threshold point. A utility circuit responds to these changes in circuit condition to provide a desired response. The compensation network includes a plurality of diodes arranged to approximate the response of the heated thermistor to changes in power supply voltage such that the voltage at the threshold point closely tracks the voltage at the sensor point in response to any such changes. This minimizes the utility circuit responding to the changes in bridge circuit conditions caused by power supply fluctuations rather than by changes in air flow velocity.

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First Claim