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# lsli04.4up - 04-1 04-1 04-2 04-2 The Wheatstone Bridge vE...

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04-1 04-1 The Wheatstone Bridge R R + - v v E R R A B C D o v v + - Raison d’ˆ etre: convert tiny changes in resistance to voltage. Shown with an instrumentation ampliﬁer . Like an ideal op-amp but with ﬁnite gain. Gain of instrumentation ampliﬁer denoted by A . v o = A ( v + - v i ). The Wheatstone bridge consists of four arms . v o = A ± R B R A + R B - R D R C + R D ² v E . 04-1 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli04. 04-1 04-2 04-2 + - v v E o v v + - A B C D Transducer can be placed in one, two, or four arms. Typical function: H t ( x )= R (1 + xk ), xk ± 1 where R is the nominal resistance of the transducer and k is a constant. For simplicity write function as: H t ( x R + R s , where R is independent of the process-variable value and R s is depen- dent on the process-variable value. Typically, R ² R s . Usually, need to convert R s to a voltage. 04-2 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli04. 04-2 04-3 04-3 Complementary Pairs Frequently, transducer pairs can have complementary responses .

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## This note was uploaded on 11/28/2011 for the course EE 4770 taught by Professor Staff during the Fall '99 term at LSU.

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lsli04.4up - 04-1 04-1 04-2 04-2 The Wheatstone Bridge vE...

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