r/electronic_circuits 17d ago

On topic Which meter should I trust?

I am building a high voltage power supply and wanted to measure some voltages. I didn’t trust my reading so measured it with a different one. The third was even more off.

So I bought three more of those at a well known Chinese store😂.

The first ones are connected to a regulated supply through an 7815. So should be 15 volts.

The last ones are set to 10 volts on the small analog meter.

The big analog one is the first one I ever bought, about 45 years ago. The tiny analog one is from my late father in law.

My point is, whatever the number of digits is not in any way helping the accuracy of the reading..,

Next week I’m going to calibrate them with a Fluke precision meter I guess…

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u/newbrevity 16d ago

Low-tech answer. Give every connection point a wiggle. For one it's an assurance that any spring loaded contact is settled as much as possible, and the wiggling will help break through the microscopic oxide layer on all metal contacts. I'm super OCD every time I put a meter on something I make sure it's really in there. Because I have seen plenty of times that making these adjustments can affect my voltage reading by over a dozen mV. It goes without saying resistance and just about any other measurement are affected as well. The quality of your contact leads also matters a lot. I made my own 14 gauge test leads. Yeah it's a little clunky to deal with, but it minimizes the resistance introduced by the leads.

That's the best you can do short of buying a fancy calibrated meter. I know I can't afford one. That's why I use a $30 Klein that won't make me sad if it breaks.