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| Microamps and Millivolts Measurements on UT61E |
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| JenniferG:
I like my UT61E I just recently bought, but the Microamps reading mode -- 3rd from last on dial -- is way off compared to the same reading with Milliamps mode -- 2nd from last on dial. The same goes for the Volts vs Millivolts measurements -- 1st and 2nd on the dial respectively. Is this normal? The volts, milliamps and amps modes all seem fine and are within spec compared to my GDM-8251A. |
| Kleinstein:
There should be no significant difference between the ranges. However the internal resistance is usually different and this can change the actual voltage / current measurend. So for the comparison one whould have the voltmeters in parallel and the amp-meters in series. |
| Fungus:
--- Quote from: JenniferG on December 07, 2022, 03:45:56 pm ---Is this normal? --- End quote --- It can be. Remember that what you're doing is inserting a small resistor in series with your circuit (the meter), and it's a different resistor on each range |
| rsjsouza:
What Fungus described above is what is called the "burden voltage", a voltage drop caused by the shunt resistor used to perform the current measurement. The UT61E has a somewhat high burden voltage when compared with many more advanced meters, but even expensive models suffer from that. This is well covered in the uCurrent project description page from Dave: https://www.eevblog.com/projects/ucurrent/ |
| bdunham7:
--- Quote from: JenniferG on December 07, 2022, 03:45:56 pm ---I like my UT61E I just recently bought, but the Microamps reading mode -- 3rd from last on dial -- is way off compared to the same reading with Milliamps mode -- 2nd from last on dial. The same goes for the Volts vs Millivolts measurements -- 1st and 2nd on the dial respectively. Is this normal? The volts, milliamps and amps modes all seem fine and are within spec compared to my GDM-8251A. --- End quote --- Can you give specifics on how you measure this and what the numerical differences are? For current, you should have the GDM-8215A and UT61E in series so you can see how much the current actually changes when you shift ranges on the UT61E. Depending on your current source the current may change quite a bit due to the higher burden resistance of the microamp range. For voltage, both meters should be in parallel. I can't think of a good reason for the millivolt range to differ from volts, but we'd need to know your exact test setup and how much variation there is. Also, AC or DC? |
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