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 <bow...@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) < > drkir...@kirkbymicrowave.co.uk> wrote: > > > >> On 25 May 2016 at 19:24, Russ Ramirez <russ.rami...@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> > > _______________________________________________ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- *John Phillips* _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.