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Questions tagged [multimeter]

Single universal measurement device that can be used to measure voltage [V] and current [A] in both AC and DC, as well as resistance [Ω]. Often many other ranges are available like frequency [Hz], duty cycle [%], capacity [F], ... Most are hand held, some more expensive ones come as a bench model.

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18k views

Wrong multimeter readings measuring 12V lead acid battery

I just got my first multimeter and when I measured a 12V 1.2ah lead-acid battery I get AC 28.8V and DC 13.4V. Is this normal? In addition I tested an AA 1.5V battery and I got 2.9V (AC setting 200) ...
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1answer
1k views

In a non auto-ranging digital multimeter, what do the increasing numbers in the Ohm section represent?

For my science fair project I am measuring the resistance of nichrome wires under different conditions. I am using an Innova 3300 digital multimeter to measure the resistance. Other websites have told ...
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3answers
18k views

9V battery and resistor are connected in series - the voltage across the resistor is < 9V. Why?

I am taking my first steps into learning about electronics as a hobbyist and I am struggling to understand something about resistance. I have read about Ohm's law and it seems fairly straightforward ...
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3answers
9k views

Why can't I measure resistance when there is current on the potentiometer?

Probably a very basic question but I have no idea why this happens. I have a 1K potentiometer. When I measure the resistance over its legs when it is not connected to anything, the results are as ...
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1answer
10k 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.
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1answer
5k views

Measuring uA current with DMM?

I'm wondering if anyone knows the accuracy of measuring uA current with a cheep (~25$) DMM? I need to measure some low power circuits (10-500uA) and I'm deciding whether I should get an analog uA ...
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3answers
254 views

AA battery current

For some reason whenever I play with a multimeter it always gives me results I never expect. In this case I am attempting to measure the current of a AA battery. I have the multimeter set to 10A on ...
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2answers
156 views

Current measurement maximum time

On my multimeter I have two current measurement connection. One for the mA and one for the A. On the ampere one there's a time limitation but not on the mA one. Also they mention in the manual a kind ...
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1answer
404 views

How to measure current with a multimeter? Currently getting inconsistent measurements

I have a current controlled power supply giving out 8 A (at least that's what I'm setting), plugged into a cable (call it #1) which is then connected via screws&crimps to a copper coil (call it #2,...
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2answers
3k views

When measuring a resistor with a multimeter does polarity matter?

When measuring the resistance of a resistor using a multimeter does it matter if I turned the resistor around and have the probes at opposite leads? Should I get the same results?
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3answers
35k 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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5answers
49k 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 ...
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6answers
48k 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....
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3answers
5k 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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5answers
2k views

Detect electrical signals from plants

My daughter wants to do a science fair experiment that involves reading the electrical signals in plants, but the cost of a multi voltmeter with data logging is very high. Can anyone suggest a setup ...
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10answers
33k 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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1answer
29k 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 ...
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2answers
3k views

How to calibrate multimeters?

Without buying an expensive calibration tool, how can I accurately calibrate my multimeters?
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1answer
2k views

Why can't a multimeter measure its own current and voltage?

Well I finally obtained another multimeter, so now I have a Mastech MS8226T and a Ben Electronic M92A. I decided to measure at which voltages would the low battery warning appear and how much current ...
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2answers
2k views

What are the dangers of a DIY fuse in a multimeter?

For the past few years I have been running my Fluke 79III without a fuse in its F44.100A 1kV fuse holder. This has meant that I've been unable to use the 40mA circuit. When I blew the old fuse, I ...
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6answers
6k 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 ...
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3answers
29k 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 ...
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3answers
427 views

What features give reason for such a wide range of prices for digital multi-meters?

Ever since high school, I've been using the same multi-meter. It works well for low voltage purposes, but I'm scared to use it for anything else (high voltage, unless it's a little zap from an ...
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3answers
15k views

Measure voltage difference between ground and DC floating power supply lines

110/220V AC to 12V DC switching mode power supply (metal enclosed, input is 220V with separate L,N and ground.) Measured voltage difference with a multimeter between V- and V+ 12V DC as expected ...
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1answer
605 views

STPM34TR multimeter IC

Hello I am working on a project that requires utility grade metering, and so we using the STPM34TR. The hardware is working and we have looked over the datasheets, the internet and anything else we ...
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3answers
2k views

4.75 digit count meters explained

What does it mean for a digital instrument when its readout is 4.75 digits "long'. And what is it like in comparison to, say a 4.5 digit meter?
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2answers
13k views

Measure high voltages with a multimeter

My multimeter is rated to 600V. How can I readily (and safely) use it to measure higher voltages?
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3answers
51k views

Why do measurements displayed in multimeter inconsistently vary by factors of 1000 depending on range?

For my science fair project, I am measuring the resistance of a 100 foot piece of 32 gauge Nichrome wire. Using a Innova 3300 digital multimeter, I get the following results for each resistance range ...
2
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3answers
680 views

Possibly Incorrect Current Reading

I'm not entirely sure if I have done the following equation correct or not, but based on the calculations, my multimeter result seems to be incorrect. I have a very simple circuit, containing a 9V ...
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0answers
676 views

Why does a multimeter in resistance mode show initial continuity over a diode?

I originally phrased this question very differently; the original text is retained below in case background information is useful to clarify the context. When I using this digital multimeter to ...
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5answers
16k views

Continuity Test on Resistor

I have a newbie question. I'm learning about electrical engineering and I bought my first multi-meter. It has a feature called "Continuity Test". I believe this test is to make sure conductors such as ...
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4answers
10k 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?
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2answers
12k 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. ...
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2answers
6k 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 ...
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4answers
2k views

Why aren't high-current ammeters protected with a fuse

Why is it that the low-current range on an ammeter (200mA) is fused and not the 20A range? I recently lost a multimeter because I connected the ammeter in parallel with a power source by mistake. ...
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3answers
4k views

Why do DMMs have so low update/refresh rates?

My DMMs ($50-$100 range) refresh the displayed value every ~250mecs. Are there technical reasons (limitations) for this, or is this just a UI thing?
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4answers
20k views

why is wall voltage measuring 175V?

I was trying to use a DM-4100A multimeter to verify a power supply, and I'm not sure I'm using the multimeter correctly. The multimeter is >10 years old too, so maybe it is not working correctly. ...
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3answers
5k views

Multimeter ranges

I am a software developer trying to understand how computers work at a lower level. I have purchased a digital MultiMeter. I realise that MultiMeters enable you to measure voltages, ohms, amps etc. ...
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1answer
4k views

How to interpret diode-mode readings from a multimeter

I'm using this multimeter to examine a heat gun fan. The fan has four contacts placed in a circle (well in a square inside a circle). Two opposite each other are labeled ...
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1answer
2k views

Multimeter reads negative even without leads

I have a cheap multimeter that used to work fine but now it has negative readings -- even when the leads aren't connected. I changed the battery, looked for a blown fuse but no luck. Any idea what's ...
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2answers
5k views

How do I fix my multimeter, which doesn't seem able to measure resistance?

I've got a Caltek CM1200 multimeter, which I bought ages ago. http://www.caltek.com.hk/cm1200.htm It can measure voltage perfectly. I'm pretty sure the battery works, as it displays 0 when you go to ...
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4answers
6k views

different current readings with a multimeter between the 200 mA and the 10 A slots

I have a cheap multimeter, which gives me different readings between the two inputs. I would like to set 100 mA using a potentiometer in a circuit, which runs from two AA batteries. If I measure the ...
3
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1answer
1k views

What's the low voltage displayed by a voltmeter when only one of its probes is connected?

Recently I was toying with a digital multimeter and observed the following. The multimeter was set to measuring AC voltage with the upper limit of 750 volts. It has two probes which I will call "red" ...
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1answer
167 views

Measuring surface and volume resistance of a cylinder with a multimeter

I'm trying to measure the surface and volumetric resistance of a cylinder shaped object using a multimeter. At what points should I place the probes, and what formulas should I be using to calculate ...
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1answer
9k views

How do I choose the right replacement fuse for my multimeter?

I have a BK Precision 2709B Multimeter. I managed to blow the uA fuse (500mA/500V fast blow ceramic) on it. Is it an ok to replace this fuse with a 500mA/1kV fast blow ceramic fuse? What impact would ...
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3answers
5k views

How usable can results of measuring MOSFET resistance with a multimeter be?

When the resistance of a MOSFET at a certain gate voltage and current is needed, the correct value is ordinarily obtained by reading the datasheet for specified values. Since a MOSFET is supposed to ...
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4answers
752 views

Failed multimeter

I have a cheap handheld multimeter that has stopped working. It basically behaves as if the leads weren't connected: the Vdc readout stays at zero, and the ...
2
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4answers
6k views

How can I test my multimeter's battery without a low battery indicator?

I a few months ago needed a multimeter, and I didn't have one. Not wanting to wait for one to arrive, and only needing it once, I went out to the hardware store and bought a cheap digital multimeter. ...
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3answers
537 views

Resistor before voltmeter

Let's say I take my multimeter and measure the voltage across the poles on my battery, I get some reading X volts. I then put a resistor between one terminal and the adjacent probe, this resistor has ...
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2answers
854 views

Not understanding why my resistor R4 for the circuit schematic is reading 35k ohms on a multimeter when its meant to be 47k ohms?

For the following circuit i am confused to as why Resistor R4 when measured on the breadboard is 35k ohms, when it is meant to be 47k Ohms (as it is a 47 k ohm resistor. Also when it is taken out of ...