Thread: Peak voltage
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Old 15th Feb 2019, 10:54 am   #16
Lucien Nunes
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Join Date: Apr 2008
Location: London, UK.
Posts: 2,508
Default Re: Peak voltage

As I understand it, John's original query was not so much around why the DC voltage is low, but why the AC and DC readings taken on the same circuit did not seem to correlate. This, I suspect, is due to the way the meters respond to the waveform present.

Quote:
I’m wondering if my digital meter and my analog meter are giving false resdings.
There's a difference between a false reading due to a defect in the instrument, and one that measures in a way that you do not want. For example, a moving-coil AC meter responds to the mean of the absolute value, but it's scaled in RMS as that is often the most useful way to indicate the magnitude of a sinusoid. However, if you present it with a non-sinusoid having a form-factor other than the 1.11 for which it is calibrated, the reading will not be the RMS value nor necessarily peak/sqrt(2). This is normal and predictable for a moving-coil instrument, although it might not be helpful for your application. Digital meters are more variable in the way they respond, so their readings can diverge with odd waveforms.
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