[volt-nuts] LTZ1000 project build

bownes bownes at gmail.com
Wed May 25 21:42:44 EDT 2016

As Dr K said, traceable and usefully calibrated are not necessarily connected. 

I can calibrate to any arbitrary standard I like.  That standard need not be traceable if all that is important to me is consistency across all the instruments in my lab. 

If I, on the other hand, want to be consistent with someone else's lab, then we need to be traceable to a common source. Thus NIST. I presume most countries have a NIST like organization. How often to they cross check each other?

Accreditation, on the other hand can be, as the good Dr. points out, pretty useless unless the accreditation body is, itself, held to some (professional) standard. 

And I'd also love to build one of these if there is enough interest. While I'm sure we can't get enough orders to get the 100pcs discount on the LTZ1000, it would be a great group project and I'd be willing to participate in bringing it to fruition. I'm also sure I can find a calibrated, traceable, reliable 3458 in the area code. 

The irony  is that while I'm less than 15Km from the New York State Bureau of Weights & Measures Metrology group, which has all the traceable standards for the state, they cannot do high accuracy for time or voltage. My personal house standards are better than theirs for those two. By a lot. Adding one of these would add a few more orders of magnitude...:)

> On May 25, 2016, at 17:06, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
>> On 25 May 2016 at 19:24, Russ Ramirez <russ.ramirez at gmail.com> wrote:
>> A lot of great information Eric, thanks for sharing the link.
>> Due to my ignorance in general on the subject of Metrology, I have the
>> following question for the list.
>> If one built a project with the LTZ1000, like the one described on xDevs
>> and could set it to a value of 7.15000000v at the NIST lab, and observed
>> stability to 7 1/2 digits, would using that device to calibrate your own 7
>> 1/2 digit DMM be considered NIST traceable? Let's say your device is well
>> insulated and battery powered, and your calibration was done at the same
>> altitude and room temperature as at NIST, plus anything I left out that
>> would make the conditions ideal.
>> The above was not meant to be a trick question, and I may have asked it
>> incorrectly, but I view the answers as instructive - or I hope they are.
>> Russ
> As far as I can determine, as long as you can work out the uncertainties,
> no matter how large they might b,  the measurement is traceable. If you use
> a 3.5 digit multimeter that is NIST traceable to calibrate a 7.5 digit
> multimeter, the calibration is still NIST traceable. The calibration will
> be pretty useless, and you may not be accredited, but it is still NIST
> traceable.
> Or if you want to be accredited, get your mate down the local pub (bar) to
> accredit you!
> On a more serious note, if people felt that design was good, and wanted to
> produce the PCBs. and/or make parts available, I'd be interested. I only
> have a 6.5 digit meter, but feel sure I could find someone with a 3458A in
> the UK who could measure the voltage for me.
> Dave <not a metrologist>
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