How to measure electrical frequency?

AI Thread Summary
To measure electrical frequency, an electronic frequency is required, which involves converting input frequencies to voltage. Various transducers can convert mechanical frequencies to electronic frequencies, with the LM2917 chip from National Semiconductor being specifically designed for this purpose. A common setup includes a generator, transformer, Schmitt trigger, LM2917, and a PLC for monitoring. There is some debate about the effectiveness of Schmitt triggers in sensing frequency without a magnetic pickup. The LM2917 primarily detects the positive peaks of sinusoidal waves, which is crucial for accurate frequency measurement.
killjoy_scofiel
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in f to V converter, input is frequencies . Is that electrical or Mechanical frequency?
 
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To convert a frequency to a voltage, you need an electronic frequency (voltage varying in time).
One can use different types of transducers to get an electronic frequency from a mechanical one.
National makes a chip, LM2917, just for this application. Check out http://www.national.com/mpf/LM/LM2917.html" where you can see the transducer (magnetic pick up).
 
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sensor transduces electrical frequencies?
how to convert this frequency to mechanical frequency(RPM),,,
i ve seen a design before, they use scmitt's trigger before f to V converter

generator--->trafo---->scmitt's---->LM2917---->PLC---->inTouchwonderware

i think schmitts don't sense the frequency...(no magnetic pick up)?

LM2917 only detect positive peak of sinusoidal wave?
http://www.imagehosting.com/out.php/i1447796_all.jpg
 
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