@gunrunnerjohn posted:1. None of the cheap panel meters on eBay are true-RMS meters, I believe I specifically pointed that out when I talked about my desire to have a pure sine wave transformer for the bench.
2. The required accuracy is really application dependent. However, I equate voltage measurements to something a wise old rifleman said once: "Only accurate rifles are interesting". Same applies to electronic measurements of any kind for me, only accurate results are interesting to me. Townsend Whelen is the man you quoted!
Lastly: What the cheap meters we're talking about do is actually exactly that, they rectify the voltage and then measure the DC value. However, that is NOT true-RMS as you'll see in the references below.
There are also a number of ways of varying accuracy to actually do true-RMS measurements. When you delve into true-RMS measurements, you'll find it's a fairly complex issue.
Below are few pages that talk about the various measurement methods. IMO, the most accurate one is time slicing the instantaneous values at a 100x or greater frequency than the signal being measured with a microprocessor and computing the true-RMS value.
Scroll down on this page and they describe the various methods of measuring AC waveforms.
How Accurate is Your RMS Multimeter?
A couple more references about RMS and true-RMS and how they're derived.
What do RMS and True RMS stand for? Here we explain you the differences
Many thanks GRJ, your always a big help and an asset too this forum.
FWIW, grj, the old rifleman you quoted is Townsend Whelen. My Dad was a fan of the 35 Whelen caliber that bears his name.
Quick question, whats the maximum panel thickness I can use too mount these meters?
@Santa Fe Jim posted:Quick question, whats the maximum panel thickness I can use too mount these meters?
From looking at the mount, I'd guess 1/8" for the two clips on the side. However, you could mount them in much thicker panels by just clipping those clips off and using a couple spots of RTV to secure them from the back.
That’s kinda what I thought, the description on EBay doesn’t give any dimensions except hole size and depth. I will order some and give it a try. Thank you GRJ for your help.
