Questions tagged [multimeter]

A multifunction measuring instrument used for measuring AC and DC voltage [V] and current [A] as well as resistance [Ω]. Many digital multimeters can also measure frequency [Hz], duty cycle [%], capacitance [F], temperature [°C], and/or other electrical or physical properties. Most are handheld; more expensive bench models are also available for applications requiring high precision.

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How should I use a multimeter to determine which AA batteries to keep and which to toss?

I have a bag of about 50 non-rechargeable AA batteries (1.5 V) that I have collected over the years. I bought a multimeter recently and would like to know the best way to test these batteries to ...
LeopardSkinPillBoxHat's user avatar
43 votes
3 answers
47k views

Why don't typical digital multimeters measure inductance?

Even with predominantly digital circuits, I am using inductors much more often than I used to, generally because of all the buck or boost converters (a recent board I was involved in has 12 different ...
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38 votes
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If I am measuring 2.3 V on a 1.5 V AA battery from Duracell, is my multimeter broken?

I recently measured a brand new Duracell AA battery which is labeled as 1.5 V. The reading was 2.3 V. Is this ever normal for a fully charged battery, or is my multimeter broken?
merlin2011's user avatar
33 votes
12 answers
26k views

Multimeter exploded during ACV measurment - What did I do wrong?

simulate this circuit – Schematic created using CircuitLab A DT-830B meter. I bought a new transformer, and I was trying to measure the output voltage. I plugged the probes on 'VΩmA' (not 10 A)...
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31 votes
5 answers
5k views

What does the multimeter dial do internally?

Everyone who has ever handled a multimeter is familiar with these dials. The position of the dial indicates the maximum range of the quantity that can be measured. But why are we required to adjust ...
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28 votes
5 answers
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Capacitor Gaining Voltage Over Time?

I recently bought two 3300uf 100v capacitors and have connected them in parallel. I charge them up to 100v and discharge them. I then hook up a multimeter and notice the voltage going up very slowly, ...
Erik's user avatar
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27 votes
3 answers
74k views

What does it mean when multimeter accuracy is marked as: ±0,03%+10Digit?

I have a digital multimeter and its accuracy for VDC is marked like this: ±0,03%+10Digit This multimeter has maximum display of 80000. So in the 80 V range it can show for example 79.999V. 0.03% ...
ria's user avatar
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26 votes
6 answers
63k views

What not to do with a Multimeter

So I just bought and installed a new fuse for an analog multimeter I scored for free and now it works like a charm. The new fuse is the same rating as the blown one I found inside, which is 0.5A 250V....
Alex W's user avatar
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25 votes
7 answers
5k views

How do we know that voltmeters are accurate?

Something that has always puzzled me is how we know the accuracy of voltmeters. From googling around, it seems that today's digital voltmeters use an ADC. An ADC works by comparing the voltage that is ...
John Allen's user avatar
25 votes
9 answers
17k views

What is the easiest way to connect a breadboard to a multimeter?

The test leads on my multimeter are too large to fit in the holes in my breadboard. How can I easily connect my multimeter to test voltage on my breadboard?
Anonymous Penguin's user avatar
24 votes
5 answers
3k views

Why are multimeter batteries awkward to replace? [closed]

I teach introductory physics labs, and inevitably when we do our labs on introductory circuits or mapping electrostatic potentials, there are one or more multimeters whose batteries die or fuses blow. ...
Michael Seifert's user avatar
22 votes
7 answers
36k views

Do digital multimeters require calibration?

This article Understanding Digital Multimeter DMM Specifications / Specs mention A digital multimeter will only be able to meet its specifications when it is within a certain environment. Conditions ...
user275517's user avatar
21 votes
7 answers
14k views

Where to leave the test leads on a Fluke multimeter

I think this is somewhat of a "trade secret". Being a software engineer for embedded devices myself, I often find myself using oscilloscopes and multimeters. I have always wondered about my Fluke 87-...
Stijn's user avatar
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20 votes
10 answers
46k views

Is it worth really buying a Fluke for hobbyist use? [closed]

Well, the question is the title: Is it worth really buying a Fluke for hobbyist use? I have a cheap meter at the moment. Is it worth spending a 3 figure sum on a nice, shiny, new Fluke? I honestly ...
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19 votes
3 answers
88k views

What is Full form of hFE of a digital multimeter?

In digital multimeter, there is a transistor-check function, and there is a term hFE. I do-not know how-to use-it, however, different Websites say it is a measurement transistor's gain ("the ratio of ...
Always Confused's user avatar
19 votes
4 answers
3k views

Determine voltage drop over 10G resistors with cheap multimeter

I have two 10G resistors connected in series with a 3V battery. I want to determine the voltage drop across one of them, which of course is 1.5V. When I use my multimeter to check the voltage drop, it ...
John Smith's user avatar
19 votes
3 answers
28k views

How does a DC clamp meter measure current?

I understand that for AC clamp meters, a changing magnetic field induces a voltage/current in a wire loop and therefore it is possible to measure AC currents by induction. But how does a DC clamp ...
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19 votes
2 answers
26k views

Can I burn components / short circuit by using a multimeter

It's probably not new to you, but sometimes we want to analyze a powered circuit with a multimeter. I love to do that, but I'm a little worried that I might burn some components or the whole circuit. ...
Antoine_935's user avatar
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18 votes
4 answers
15k views

Using diode mode on my multimeter to debug circuits. A good idea?

I've seen a few YouTube videos where the presenter, who appears to be experienced in board repair of Apple (and presumably other) circuit boards recommends to use your multimeter in "diode mode" to ...
Nick Gammon's user avatar
17 votes
6 answers
8k views

Why isn't there any 9.5 digit multimeter or higher?

Why can't you buy a 91⁄2-digit multimeter? Isn't there any need for it? Is a 81⁄2-digit multimeter the latest high end you can buy? I have tried Keysight, Keithley, and Fluke, but there is nothing ...
voltage_drop's user avatar
17 votes
8 answers
19k views

How to measure gigaohm resistors?

I've got an issue that appears to be caused by damaged resistors that are either open circuited or of too low a value due to contamination. The problem is that they're gigaohm resistors, so to a ...
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17 votes
4 answers
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What to look for in a multimeter?

When selecting a multimeter, what should one look for in terms of safety features and measurement capabilities? What can you look for in the specifications to tell a good meter from a crappy one (...
Grant's user avatar
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16 votes
2 answers
3k views

Why doesn't my multimeter show the correct Zener reverse voltage?

I have a 3.3V Zener diode, brand new from a reputable source. When I set my Fluke 101 multimeter to diode test mode, and put the black lead next to the dark bar on the diode and red on opposite side, ...
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16 votes
5 answers
70k views

What is the difference between a multimeter with RMS and one with True RMS?

I am looking for multimeters. I am only a beginner in electronics, but I want to buy one that will be good enough for me for a while. I found a multimeter that measures True RMS, and another one that ...
Neinstein's user avatar
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15 votes
2 answers
4k views

3.3M resistors not registering on multimeter - are they faulty?

Please keep in mind this is my very first electronics project so it’s entirely possible I’m doing something wrong. Here’s the deal: I’m building a contact microphone from a kit that came with four ...
Michijake 's user avatar
15 votes
4 answers
19k views

What's the hold function on a multimeter for?

All it does on my multimeter is freeze whatever value it was reading at the time. When would I need to use this?
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15 votes
6 answers
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How to calculate the maximum current a AA battery can deliver for a short period of time?

I want to measure the maximum current a AA battery (full charged) can deliver for a short period of time (let's say one second) I have in mind to do this with a multimeter : setup multimeter to ...
tigrou's user avatar
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14 votes
4 answers
6k views

Why does most test equipment have 10 MΩ voltage input impedance?

I'm only speaking for equipment interesting in voltage measurements. Multimeters, oscilloscopes and conventional lock-in amplifiers seem to have mainly input impedances of 10 MΩ. I understand the need ...
BlackPenguin's user avatar
14 votes
5 answers
3k views

5V LDO blowing up only when testing current draw

I have a circuit to power some 5-volt logic from a +24VDC source. It has some basic reverse-polarity protection and uses a TI 5VDC LDO. It all works great during normal operation however, when I use ...
user2434889's user avatar
14 votes
2 answers
12k views

Why does a multimeter put more voltage to measure a smaller resistance?

I noticed this behaviour on two different multimeters (different models and brands as well). At first I did not put a multimeter in the way to measure how much voltage changed for the different scales ...
Dakatine's user avatar
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14 votes
4 answers
18k views

What does it mean that a multimeter is four and a half digit?

The fluke 87-V is advertised as a "four and a half digit" meter. What does that mean, how does half a digit fit into the equation?
David Högberg's user avatar
13 votes
6 answers
7k views

Why are these readings violating ohm's law? (Are they?)

I'm brushing up on my high school electronics knowledge and I decided to experiment with a small acquarium pump I had lying around. I took some measurements with a multimeter and the results confuse ...
Bas's user avatar
  • 463
13 votes
5 answers
71k views

how to measure the internal resistance of a voltmeter?

How to find out what is the internal resistance of a voltmeter? I imagine the higher the better - it'll have less influence on the measured circuit. What is the approximate internal resistance of ...
ria's user avatar
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13 votes
2 answers
11k views

Why one of my multimeter shows a small voltage when only one probe is connected to AC and the other dont?

I've recently acquired a Minipa ET-997 multimeter. I noticed that when I connected one probe to 127V phase and let the other disconnected, it will show around 12V. But I have an older and cheaper ...
Fabricio Breve's user avatar
13 votes
3 answers
62k views

How to check if my multimeter's fuse is damaged?

I recently bought a cheap multimeter. I played around measuring stuff on simple circuits and I think I managed to damage it as I don't seem to be able to measure current anymore (always get zero ...
geo909's user avatar
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12 votes
6 answers
5k views

Why can't capacitors on PCBs be measured with a multimeter?

While looking at this article, it mentioned that one cannot test the capacitance of a capacitor while it is on a PCB. The explanation given is: The reason is, that when a capacitor is inside the ...
HFOrangefish's user avatar
12 votes
9 answers
7k views

In which scenarios is it important to measure microampere?

With the situation of finding a new multimeter, I found myself lost to the number of available devices on the market. For sure, to find the most suitable device I have to set some requirements. While ...
Toby N.'s user avatar
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11 votes
5 answers
3k views

Did a blown fuse in my multimeter damage my multimeter?

May be a little newbie question, but I since I am an electronics beginner and couldn’t find a direct answer I will ask it. I blew the 600 mA fuse on my brand new multimeter, I think I didn’t change ...
Hoekplaat's user avatar
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11 votes
3 answers
13k views

"Beep" when testing VCC and GND with the multimeter

Sometimes I use my multimeter solely for testing if there is a contact between two points. However, sometimes, when I measure between VCC and GND on some of my PCBs, I hear a short "Beep" and then it ...
arc_lupus's user avatar
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11 votes
4 answers
8k views

Fuse blowing in 12 multimeters rated for 200mA, only measuring 12.5mA. Why?

I'm a high school electronics teacher and while doing a lab on Ohm's Law we just blew the fuses in 12 out of 18 brand new digital multimeters while measuring current, and no the meters were not hooked ...
Craig's user avatar
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11 votes
1 answer
13k views

How does autoranging work in a multimeter? What is the circuit?

I was curious how this is done. It seems you would have to vary the voltage and current to measure resistance from 1ohm to 10Mohm.
Bill's user avatar
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11 votes
1 answer
55k views

How to determine the units when reading a multimeter?

Say for instance I am trying to measure the current. The units around the edge of the multimeter is 2000u, 200m, 20m, 10A, etc. Does this mean that the reading displayed on the multimeter is in that ...
Wk_of_Angmar's user avatar
10 votes
2 answers
2k views

Reasons not to use these leads

I found the following note with a set of test leads we use for our Agilent 34461A[1][2]: This Test Lead Set is designed for use with the Agilent 34xxxA Multimeters, and also the U274A, U3401A, and ...
Mast's user avatar
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10 votes
3 answers
1k views

Why might a multimeter ask for "wrong" fuse sizes?

Why might a multimeter ask for the "wrong" sizes of fuses? On the front of my Fluke 87 multimeter, the two probe ports for amperage are labeled as fused at 10A (max) and 400mA (max). When opening the ...
Coldblackice's user avatar
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10 votes
4 answers
2k views

Why do multimeters have an aluminium foil at the back?

I was wondering what is the purpose of aluminium foil at the back of some multimeters? I did a continuity test and found that it is connected to the ground (COM) terminal. My initial guess was that ...
user avatar
10 votes
2 answers
4k views

How to calibrate multimeters?

Without buying an expensive calibration tool, how can I accurately calibrate my multimeters?
csadam's user avatar
  • 1,646
9 votes
4 answers
3k views

Differences between oscilloscope, multimeter, and power supply voltage readings

So I recently got myself an oscilloscope and am trying to learn how to use it by starting with the basics, a circuit with a voltage source, and a resistor. When I set my power supply to 5V, the ...
dka13's user avatar
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9 votes
5 answers
7k views

When we should use only an "analog" multimeter?

I know electronics testing with digital multimeters is easier than analog, but I'm wondering whether there is any electronic testing which can done with only "analog" multimeters? For ...
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