[SI-LIST] Re: AC Waveform question
- From: "Jackson, T L" <t.l.jackson@xxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Mon, 07 Oct 2002 09:26:40 -0700
A normal analog meter is an averaging meter. The mechanical damping to make
the needle steady is a low-pass averaging filter. So if you measure AC on a
DC setting, you get an averaged measurement.
For AC or rms scales, it is still making an averaging measurement, But, the
result are scaled by the rms/average scale factor for a sinewave. If the
waveshape is not a sinewave, the rms reading may be accurate, but not
calibrated.
TJ
Thomas L. Jackson, PE
Senior Staff System Engineer
L1-50, Remote Sensing Systems Engineering
Missiles and Space Operations
Lockheed Martin Space Systems Company
telephone: (408) 742-2013
facsimile: (408) 742-7701
location: B149/E2
-----Original Message-----
From: Zabinski, Patrick J. [mailto:zabinski.patrick@xxxxxxxx]
Sent: Monday, October 07, 2002 9:10 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: AC Waveform question
Doug,
Is your meter set to "AC Volts" or "DC Volts"?
My understanding is that "AC Volts" on a meter will
measure the RMS value, while the "DC Volts" setting
will measure the average value.
Pat
>
> Hi all,
>
> I know I must have learned this in school, but now I'm not
> sure of the answer!
>
> Assume I have a full-wave rectified sine wave of low
> frequency. Assume the
> magnitude is 1.0 Volt peak (zero to peak). Assume I apply
> this wave form
> across an ordinary 1 Volt analog meter. What does the meter read?
> The RMS value (.707 Volts) or
> The average value (.636 Volts)
>
> Doug
>
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