Simple DIY DVM Voltage Reference

[Mark Hennessy]

Thermal converters are OK, but have two serious drawbacks:

1. They are fairly inaccurate (powerin->heater->thermocouple/thermistor->reading).
   
2. They draw significant power from the DUT
   

Perhaps in isolation, but not in the Fluke 8920A I mentioned. The input impedance is 10MΩ, and the accuracy is 0.5%.

The Fluke 87V is 0.7%. Even the 287 only manages 0.4%.

On the plus side:

1. They are simple
   
2. Handle any waveform
   
3. Very wide bandwidth
   

So they are ok for power measurement, but of little use for small signal work.

The lowest range on the 8920A is 2mV FSD. Admittedly, in this range, the BW falls from 20 to 2MHz, but if this matters, you can stop it auto-ranging into that range.

As I said before, highly recommended