shabaz created a DMM measurement accuracy graph for his MP730624 Multimeter Quick Review: Surprisingly Accurate! blog. The graph shows the spec-ed accuracy of a MP730624 . He also shows graphs for other meters, like the 121GW. And I have one of those.
image source: shabaz' blog
I ordered a reasonable accurate (0.01%), calibrated voltage reference to put that meter to the test. And compare theory to reality. While I'm waiting for that reference to arrive, I'm playing around a little. I'm testing it with two voltage references on the Digilent/TI Analog Shield. A LM4128-2.5 and a REF5020.
I don't want to achieve or prove anything in this post. Just measure. I added a DMM6500 for comparison.
Circumstances:
- It's a hot but dry +30°C day. The references and meters have been on for more than half an hour.
- 5 V input is the 5 V from an Arduino UNO R3 powered by a laptop's USB.
LM4128-2.5
This is a 2.5 V reference.
Results:
REF5020 Low-Noise, Very Low Drift, Precision Voltage Reference
This is a 2.048 V reference.
Results:
That's it. I did not analyse, just power on, let it stabilise, and measure. Thoughts and comments below 
