Re: Accurate voltage calibration


Alfred Green wrote:
I have recently aquired a nice 5.1/2 digit DVM, and would like to assess
the absolute accuracy. Many years ago I had a 'Standard Cell', but that
got lost in one of my several relocations.
What is a good alternative these days? I would think that there is a
semiconductor device that has a known threshold. I am familiar with the
Wheatstone bridge method to measure voltage without affecting the reference.
Once I have a good DC reference, getting AC & RMS calibration is fairly
easy.
Having a GPS locked time and frequency reference, I am used to being at
the 1e-10 accuracy level for those, but if I can get to 1e-5 for analog
voltage I would be very happy.
Any suggestions gratefully received.

73 Alf NU8I
Scottsdale AZ DM43an
160m - 10 Gigs

I don't think there is an easy to do what you want, otherwise people
wouldn't spend lots of money getting their standards calibrated at
national standards labs like NPL. Your best bet might be to find
someone who has access to a regularly calibrated DVM and check it
against that, or send it away to get it calibrated.

Standard voltage diodes are available and are used as secondary
standards, but are probably quite expensive and difficult to find.

You should have kept your Weston cell. 8-) BTW, NPL even offers a
calibration service for them, the volt is defined using a Josephson
junction, these days.

73, Leon

Leon

.

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