0.01% of 12V is 1.2mV, most 3 terminal references have noise which is much
greater than this. Something like a Linear Tech LT1963A will get you into
the tens of uV -- but all the associated components have to be tightly
wound.

If you go into the Linear TEchnology webiste (www.linear.com) and look at
the application notes there is an article by Jim Williams which describes a
20 bit DAC -- too complicated to get into here -- what you can do with one
of these DAC's would take a Fluke 3330B calibrator two decades ago.
http://www.linear.com/pub/document.h...pp&document=92

If you are going to calibrate DVM's you'll find some real bargains on EBay
under the business equipment/test equipment/calibrator section. It helps if
you have a university with a well equipped lab -- you can compare purchases
with standardized equipment.





"Gary Schafer" wrote in message
...
I am looking for an accurate voltage source around 12 volts to use to
check calibration on digital voltmeters. .01% would be nice.

Does anyone know about the 3 terminal voltage reference chips
available? Would they do the job?

Thanks for any help.
Gary K4FMX