[volt-nuts] 732A drift

[Andre]

Hi, first post!
Yeah, I ran into this issue a while back. Fortunately for most applications 10mV resolution is fine (eg measuring charge state on Li-ion cells) but I did find that old meters do seem to experience random drift failures of precision resistors and more so trimpots. Would it be a good idea for someone to do a "732 FAQ" with likely faults that would cause a particular matrix of symptoms?

Also how do you deal with failures where a precision component has "gone bad" ? Surely all the calibrations are suspect which is why any sensible engineer always has two references at a bare minimum and sets up a master/slave or main/backup then maintains a calibration table of each? so if a drift is seen then the "bad" unit can be dealt with sternly.

I looked into making a 10.0000Vref a while back and had some success with active feedback via thermal pad: it almost worked but in the end it was cheaper and simpler to buy one ready made (cough REF02 /cough)
Also relevant, since originally buying my RS IDM65 you can now get I2C precision CT references which can replace the troublesome parts
with something that does not drift, ever!

-Andre


________________________________________
From: volt-nuts <volt-nuts-bounces at febo.com> on behalf of Alan Ambrose <alan.ambrose at anagram.net>
Sent: 30 August 2017 17:33
To: volt-nuts at febo.com
Subject: [volt-nuts] 732A drift

>>> My 732A<x-apple-data-detectors://28> e.g. has a drift of only about 0.2ppm pa over a couple of year

Hope you don't mind me jumping on this thread and asking a basic question: is there any kind of procedure for the 'enthusiast' (say with single 3458A/single 732 and not say 4x732) to measure the drift of a particular 732.

Alan
_______________________________________________
volt-nuts mailing list -- volt-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.