Brian Kirby wrote: > search LTZ1000, LM399, and LH0070 at www.linear.com , also get app > notes AN42, AN82, and AN86 - and by the way, most big parts houses > have quit carrying these references - but they can be ordered direct > from Linear Technology. > > The LTZ1000 is used in HP3458A multimeters and a lot of voltage > calibrators from Datron, Fluke, etc. The LM299 and LM399 were used in > HP 3457A and HP3456A, and others. > > more info on LM199/LM399 at national semiconductor, and a few app notes, > AN 161 , AN184, > > finding a good standard cell, is hard to do nowadays. I bought 6 units > on ebay, 2 were from folks that had them and they were able to test and > furnish data, and the other four were old and the voltage was too low > to be stable. Basically if the voltage is not 1.0183 volts and above > they are no good. They are finicky and I would read up on them before I > would purchase one. NIST had a paper on them that explained the history > of them, their construction, and how to handle them and the temperature > conversion formulas for the saturated cells. Check out NIST 250-28 > Solid State DC Voltage Calibrations, A Sub-PPM Automated 1-10 Volt DC > Measuring System by Bruce E. Field, NBS Measurement Services: Standard > Cell Calibrations, also by Bruce E. Field, Standard Cells - Their > Construction, Maintenance and Characteristics by Walter J. Hamer all at > NIST. > > Look up Kelvin Varley dividers - I don't know if these folks are still > in business Julie Labs and ESI. Leeds and Northrup made a few also. > > One of the best ways to ensure you get a good Weston standard cell is to make your own. However obtaining the Mercury and the Cadmium sulphate may be difficult. The mercury salts are easily produce by electrolysis in a dark enclosure (they are photosensitive).
Julie research labs are long gone, however http://www.ohm-labs.com/ make some of the instruments and standards they used to sell. They also claim to have taken over from Leeds and Northrup. Also see: http://www.ietlabs.com/ Fluke still make the 720A KVD. > HP had some app notes on measurements, look up the 3456A, 3457A, 3458A > and it should show some app notes for them. > > Zicor had AN177, I believe Intersil bought them > > And Keithley had a free book called Low Level Measurements Handbook - > Precision DC Current, Voltage, and Resistance Measurements thats worth a > read. > > If you can find a copy of Current Sources and Voltage References: A > Design Reference for Electronics Engineers, by Linden Harrison, its a > good read on a lot of semiconductor references in the last 15 years or > so - I would see if you can find it in a library somewhere, if you > purchase it its about $50-75 on the used market. > > Brian - KD4FM > > John Ackermann N8UR wrote: > >> I'm interested in learning some basics about precision voltage >> calibration (as can be realized by the hobbyist, not Josephson Junction >> systems!). A Google search hasn't turned up anything like a tutorial. >> >> Anyone know of any good app notes or other references on things like >> standard cells, zener references, precision potentiometers, etc? -- and >> how to use them? >> >> Thanks, >> >> John >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.