[Phys-L] Re: Digital Multi Meters (DMM)

[anngeorg at PACBELL.NET (Bernard Cleyet)]

The EMF during the sampling, I suspect so.  So if you want a long time
average (long compared to the one that samples many times a sec.) one
must search for ancient ones -- I think it was JD who described a Radio
Shack painfully slo one or a d'Arsonval would be especially good.
another method:  add an external integrator (capacitor).  another method
would be to up load to a computer and perform a spread sheet average, or
use loggerpro and GRAPH it.

bc, who used a large (a few microF.) one to average the signal from a
noisy klystron in FTIR xpt.

Ludwik Kowalski wrote:
> Two weeks ago I asked about digital multimeters in general. Now I have
> a specific question. Suppose I am using the instrument as a d.c.
> ammeter. The current is unidirectional but not constant. The i(t)
> fluctuates randomly (as if a strong noise were superimposed on a
> constant I component). Will the mean current be measured correctly by
> the instrument?
>
> Ludwik Kowalski
> Let the perfect not be the enemy of the good.