Johnson Controls Gmbh

William J Riebe

Scott B Bramow

Louis J Crum

A square root signal extractor generates an output signal which is a square root function of an input signal. First and second diaphragm amplifiers have cascaded output chambers connected to a high gain output amplifier. The first and second amplifiers are connected as the non-inverting input and the inverting input respectively of the operational amplifier. A high gain output diaphragm amplifier is connected to the inverting amplifier output. The output diaphragm amplifier is constructed such that only a low level input pressure change is required to create a full swing of the output pressure. A non-linear input restrictor and a linear feedback resistor are connected to the input chamber of the inverting amplifiers. The feedback resistor has a significantly greater resistance than the input resistor. The non-inverting diaphragm amplifier is connected to the transmitter by a fluid repeater. A reference signal source is connected to the input restrictor and thus to the inverting input. The input restrictor is selected such that the differential pressure across the restricter is the square root of the flow. An adjustable fluid resistor is connected between the non-inverting and the inverting inputs which creates a flow path between the transmitter and reference source. The fluid repeater prevents loading of the transmitter.

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West Allis, WI, United States of America

William J Riebe