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False reading

JimB

Super Moderator
Most Helpful Member
Quick answer - yes.

JimB
 

unclejed613

Well-Known Member
Most Helpful Member
yes... digital multimeters have a very high input impedance, usually 10Megohm or more. random electrostatic or electromagnetic fields will induce voltages on the terminals. even more so with test probes plugged in. even your body can carry a very strong electrostatic charge. somewhere i have seen that the capacitance of the human body is 100-200 picofarads that's easily enough to couple a few millivolts of 50/60hz AC from your surroundings to the meter if you hold one of the probes in your hand.
 

Reloadron

Well-Known Member
Most Helpful Member
Yes, I have seen plenty of them do that for the reasons mentioned in Post #3. It's not at all unusual.

Ron
 

KevinW

Member
It just started doing this lately, usually it counts down to 0 but it seems to be holding at different readings.
I'm debating sending it in for repair but I might be better off to replace it.
 

Reloadron

Well-Known Member
Most Helpful Member
It just started doing this lately, usually it counts down to 0 but it seems to be holding at different readings.
I'm debating sending it in for repair but I might be better off to replace it.
They can't repair it if it isn't broke. One more time, what you are seeing is normal. I have Fluke 87 meters which drift less an input and free cheap meters that do it. Sometimes they do and sometimes they don't. There is no rhyme or reasoning a pattern. What is important is the measure as they should when they should. Some tend to drift when open circuit more on AC than DC ranges, primarily voltage. Now if you want to send it back to somewhere then if it makes you feel better have at it.

Ron
 

gophert

Well-Known Member
Most Helpful Member
As of right now it's working again so that makes me feel better for the time being.
Make sure the battery is good. Also, it is common on AC setting and even more common on "mV AC" setting. A few 10ths volt on DC is common as well.
 

unclejed613

Well-Known Member
Most Helpful Member
usually it counts down to 0 but it seems to be holding at different readings.
in moist air it will count down to zero because the moisture is draining off electrostatic charges. it's winter, so generally in cold weather, the air is much drier, and doesn't bleed electrostatic charge as well as moist air.
 

dr pepper

Well-Known Member
Most Helpful Member
One very crude test you can make with a meter is connect the leads to a device or pair of wires, then shake the leads from the meter, if the reading varies you know there is a high impedance or open on said wires, I've sometimes used it when theres a likelihood of mains voltages being present.
 

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