Texas Instruments Corporation

Edward F Racca

Dale R Sogge

Neal Pugh

Norman E LeComte

A capacitive transducer (10) has a housing (12) which receives a variable capacitor (14) in a fluid pressure receiving chamber (12e). A support (20) is received on an annular shoulder (12j) formed in the sidewall (12h) of the housing. The support has inner and outer concentric ring shaped lands (20k, 20l) with the inner ring shaped land engaging the variable capacitor (14) inboard of the outer peripheral edge of the capacitor. A shelf (20d) is formed on the sidewall of the support which receives a first relatively rigid substrate (26a) of a circuit board which has a second relatively rigid substrate (26b) bent through a connecting flexible strip so that the second substrate overlies the first substrate within a circuit receiving chamber (20c). A ratiometric signal conditioning circuit portion 28a and voltage regulating circuit portion 28b are mounted on the circuit board. The voltage regulating circuit is used to convert the transducer into a variable supply/fixed output device and includes a precision voltage regulator (U2) having an input capability of a portion of the range of the variable supply voltage, an NPN transistor (Q1) to provide a variable resistance in the primary current path, a zener diode D3, a current regulating diode (D2) to bias the transistor and the zener diode, a blocking diode (D1) and associated capacitors (C13, C14, C15).

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Warwick, RI, United States of America

Edward F Racca