June 15th 05, 08:15 AM
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On 14 Jun 2005 23:39:00 -0700, wrote:
I am trying to use a wheatstone capacitance bridge to measure a very
special capacitor that will change value in some frequency. To be
precise, the gap between the capacitor plates will shake back and forth
in a known frequency. I need some knowledge about the noise and sample
rate of the capicitance bridge, so that I know I got a good data. Any
idea about what reference book I should read. Thank you.
Hi Herman
You working with Phonon Polaritons?
A Wheatstone Bridge is not the best capacitance measuring bridge,
however, you may not have that option. A bridge of any sort is not
sample rate limited, the detector (or indirectly the method of
excitation) is. By and large, a bridge is a linear device and if you
want to use it as a demodulator, then you want to run the source
frequency of the excitation at least ten times faster. Nyquist would
demand at least twice, but that is not very useful to run at the
ragged edge if you want "good data."
Depending upon this excitation frequency, the utility of the common
Wheatstone configuration may degrade. It all depends on what you
consider to be accuracy.
73's
Richard Clark, KB7QHC
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