| Electronics > Beginners |
| How do i calibrate my multimeters! |
| (1/4) > >> |
| XMA:
hi there so i got 2 multimeters, I've done some tests and it seems the voltage readings are off, here are comparisons. now my question is how do i calibrate them, i know that the cheap Chinese one has 1 potentiometer that u can calibrate it with and the thing with that is if i calibrate it, after 1 day it goes inaccurate again, and it be acting wierd by not reading voltage but it goes up and up, my guess its toast, now to me another meter, i dont know exactly how many potentiometers it has but i saw 2, so my question is what potentiometer would i need to adjust? Cheap Chinese Multimeter: LI-ION BATTERY VOLTAGE READING: CHARGER - 4.12v MULTIMETER - 4.10v BENCH POWER SUPPLY READING: BENCH - 4.2v MULTIMETER - 4.18v Cheap Chinese Multimeter voltage difference 0.02v MICRONTA 22-188: LI-ION BATTERY VOLTAGE READING: CHARGER - 4.12v MULTIMETER - 4.06v BENCH POWER SUPPLY READING: BENCH - 4.2v MULTIMETER - 4.14v-4.15v MICRONTA 22-188 voltage difference 0.06v |
| Kleinstein:
For a reasonable calibration is needs an accurate source or meter - normally something at least 10 x better is recommended. So without a much better meter / source, there is not much sense in adjusting the meters. With 20 / 60 mV off at 4 volts this 0.5 and 1.5 off - good enough for a cheap Chinese meter. With the cheap posts, there is a chance the surface is oxidized and it might need a few movements to clean, before doing an adjustment. How the adjustment is done is meter specific. In old ones it can be a pot, but in new ones it might be all software. |
| Old Printer:
From what you have posted I would not feel confident that eith of your two "control" voltages are any more accurate that your meter. Neither the charger or the power supply should be expected to be used as a voltage reference. The exception would possibly be a very high quality lab PS that had been recently calibrated. We would need to know more about it, but at this point I would tend to trust the meter before either of those. |
| rhb:
Get a bunch of new AA cells and put some in parallel after removing outliers. I forget what the voltage is, but I don't mind measuring a dozen with my 34401A. Another option is the AD584JH voltage references on eBay for $3 each. Those are good to better than 0.1%. I bought a DMMCheck Plus from Doug Malone, but it's a good bit more expensive. But exactly the tool for the job. |
| rstofer:
The DMMCheck source: http://www.voltagestandard.com/DMMCheck_Plus.html |
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