I'm measuring thin foils, kelvin probe style, and the panel meters (200mV style, 3.5 & 4.5 digit, battery powered, independent ground) aren't cutting it. The last digit(s) always seem to drift/dither/flutter. I've tried this-and-that, decoupling capacitor, decoupling capacitors, on the supply, across the VIN, battery, etc. I don't see the flutter in my multi-meters, so I don't understand yet why? I might ignore the last digit fluttering, but others in my dept. are tasked with recording data, and with their limited training, this can be problematic.

I'm considering a benchtop volt meter, 4.5 to 5 digits, but only if it doesn't "digit-dither" or "hunt" excessively. As I mentioned, the handheld DVMM's I'm using don't do this. I might try this as a solution, but again, with technicians of limited training/understanding, initial setup can be intimidating.

So, my question(s):

1) What might I try to stop "digit-dithering" that I'm experiencing with my vanilla 200mV panel meters.
2) Do more expensive bench-top voltmeters ($200-500, used or new) also experience this problem?

 

How many digits are the multimeter and the panel meter? If the problem is noise in the signal, a higher resolution meter will make it worse.

The ultimate solution might be to sample less frequently. What time resolution do you need?

 

Cheap

Better

Typical specs. You don't get what you don't pay for.


Tell them to ignore it or replace them with analog panel meters.

 

It is com for the last digit to be uncertain. If you were close to me, you could just try several meters I have.

 

Do the digits flutter when measuring a battery voltage?

 

1sec sample rate is adequate. Measurement range is 4.5mV to 220mV. Yes, flutters with battery powered voltage reference.

 

Are these "real" DPMs based on the dual-slope Intersil chips of our ancestors, or modern ones that use mystery Chinese microcontrollers? The microcontroller ones aren't linear when compared to my Fluke.

 

independent ground

That might be the cause of noise pickup?

 

Keep in mind the panel meters are simply that - read the input and display its quantized value. While this is good for certain applications, it can potentially show the scattered nature of measurements, especially if they are sub-1V.

DMMs use other techniques to improve readability and accuracy, such as averaging and variable acquisition speed.

You might be able to improve the panel meters' stability by performing some averaging on its input.