[R-390] DMM bounce

[Joe Foley]

What frequency are your voltmeters calibrated for?

Joe



--- Dan Merz <djmerz at 3-cities.com> wrote:
> Hi,  here's a general question related to making
> resistance measurements
> when an inductance is involved,  e.g. the winding on
> an audio
> transformer.  Generally,  I make such measurements
> either with my BK
> DMM on a fixed scale setting or with a Simpson 260
> old-style
> multimeter,  and I usually have no problem.  But
> recently I repaired an
> audio transformer and sent it to the lucky guy and
> he emailed that the
> primary was ok but his digital meter just bounced on
> the secondary and
> never settled on a reading.  I thought maybe I made
> a bad solder
> connection.   The approximate inductance of this
> secondary is about 360
> henries.  He sent it back to me and I measure it as
> ok,  about 1500
> ohms,  using my usual methods.  I do notice that the
> reading shows a
> couple of high reading before settling down.  This
> doesn't happen on the
> primary which is much lower inductance.  My question
> - are there some
> DMMs,  maybe the autoranging types,  that have
> problems with such
> measurements.  I could imagine this could happen
> depending on the rate
> at which it tries to "range" the reading but it
> would seem that it
> should eventually settle down.  He tried it with two
> different digital
> meters and couldn't get a stable reading.  I
> sometimes use this
> measurement method on 390a parts,  hi.   Hopefully
> waiting for
> illumination,  Dan.
> 
> 
>
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