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John Robertson John Robertson is offline
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Default Full wave voltage reading

On 2019/07/08 7:47 a.m., Bob Engelhardt wrote:
If I measure a full wave voltage with a non true-RMS common variety
DMM*, will it be off by a known factor, from the true RMS value?

Or is there a rule of thumb about the error.Â* E.g., the reading will be
high by about 10%.

Thanks,
Bob

* - Extech Ex320 if it matters


Typically these inexpensive digital meters are only fairly accurate for
60 or 50 Hz sine wave AC voltages. The further away from 50/60 Hz and/or
true sine wave you get the worse the reading accuracy...

Here is a good explanation:

http://sound.whsites.net/appnotes/an012.htm

I'd use a 'scope and do the math if the readings are critical and you
can't afford a proper AC meter

John :-#)#

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