[volt-nuts] LTZ1000 project build

John Phillips john.phillips0 at gmail.com
Wed May 25 23:19:31 EDT 2016

If you build these you need to build several and age them together and see
how the members drift against the population. After 6 months or so you
should be able to tell which ones are stable and weed out any drifters.

On Wed, May 25, 2016 at 6:42 PM, bownes <bownes at gmail.com> wrote:

> 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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*John Phillips*

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