As far as DMM voltages standards, no need to build one for the 4.5 digit meters. Doug Malone sells an excellent Xicor based reference that runs off a 9V battery for around $30 shipped. Mine checks out to better than 0.00005V on all my 6.5 and 7.5 digit meters. He sells them on Ebay under them user name zildjianboy7 (see item number 280292722286). There is also the Geller Labs unit, potentially more accurate, but it needs an external supply. It would be nice if they had 2.0V (or 1.9V) units available for checking those X.5 digit meters to better accuracy.
I am a bit of a mass nut (OK I have a LOT of digital scales with resolutions down to a nanogram and up to 60Kg with 0.01g res). Many of the industrial scales require you to enter your lat/lon/altitude (or at least your general location) so they can better model and compensate for gravity. A 3 meter (1 story in a building) change in altitude affects gravity by 1 part/million... easily noticeable on even a modest analytical balance. Modern lab balances can easily resolve 1 part in 20 million. The better ones exceed 1 part in 100 million. Industrial scales can do 1 part per million of max capacity... not too shabby for a mass to digital converter. _________________________________________________________________ Send e-mail faster without improving your typing skills. http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_speed_122008 _______________________________________________ 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.
