[volt-nuts] Calibration Device

J. Forster jfor at quikus.com
Mon Aug 12 12:09:54 EDT 2013


My main interest is as a 'sanity check'. I use DMMs for engineering purposes.

Shields up:

IMO, there are very few applications, other than fundamental physics
research, that really NEED 5,6,7, or 8+ digits.

I would no more use a multi digit DVM to do what can be done with a
differential voltmeter than use a carrier phase tracking GPS to measure
for a living room carpet.

Shields down.

-John

================



> John wrote:
>
>>David mentioned this:
>>    *   *   *
>>What do people think of the device?
>
> What are you trying to accomplish?  As I posted previously:
>
>>Let's assume that it is still working exactly the same as it was
>>when it was calibrated.  The calibration values are recorded to
>>4-1/2 digits.  So the uncertainty is greater than the two LSDs of a
>>3457A.  Of course, it is almost certainly not working exactly the
>>same as it was when it was calibrated, [so its last digit is going
>>to be uncertain,] which is going to put at least the third LSD of a
>>3457A in question.  So it is good enough for a 3457A only if one is
>>content with a 3-1/2 digit verification on a 6-1/2 digit instrument.
>
> You should be able to rely on it to verify instruments to 3-1/2
> digits.  Beyond that, you would need something with a smaller uncertainty.
>
> Best regards,
>
> Charles
>
>
>
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