On Thursday, 21 September 2017 20:24:48 UTC+1, T i m wrote:
On Thu, 21 Sep 2017 12:05:59 -0700 (PDT), tabbypurr wrote:

snip


How accurate do you want the readings?

As accurate as the meter can be itself, ideally.

Your total error is all the errors added together, so you'd need some exceptional circuitry to not add anything significant to the meter's error, which might be 1% or so. More realistic would be to keep the electronic errors within 1%.

To get that you'd be using an opamp to knock 10v off, with 0.1% resistors everywhere it matters. Avoiding anything getting hot always helps keep the errors down, so anything that gets warm heatsink it, and operate parts way under their limits. Not that that will be a problem with this meter.


NT

Add your errors together. MC meters are usually pretty good on accuracy.

Ok, hopefully the biggest issue will be parallax error and my old
eyes. ;-)

Cheers, T i m