Hewlett-packard Company

David E Clouser

John S Craven

Steven J Engel

A sample fluid and a reference fluid are alternately applied to a fluid detector and an output signal is derived that is proportional to the difference between the response of the detector to the fluids.

Modulated fluid detector

The linear component appearing in the output of two logarithmic amplifiers connected for temperature compensation and having matched feedback semiconductor devices is cancelled in a resistor connected in series with a logarithmic device between the output and a point of reference potential so that a purely logarithmic voltage appears at their junction.

Method for extending transistor logarithmic conformance

A thermal conductivity detector in which sample gas and reference gas are made to alternately flow through a thermal conductive cell at a given switching frequency and in which the output signal is applied to a synchronous detector wherein it is mixed with a control wave that is in phase quadrature with the flow component of the output signal.

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Claymont, DE, United States of America

David E Clouser