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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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446 views

measurement of differential signals using multimeter

Though differential signals are measured through oscilloscope or differential probe, i tried measuring the signals through a multimeter out of curiosity and my observation was that when a voltage was ...
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3answers
422 views

How to check continuity or shorting using arduino

I was trying to build a multimeter using an arduino (just for learning purpose). I am able to measure voltages directly using analogRead() and for measuring currents I am using a o.o1ohm shunt ...
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75 views

Is it really problem if 0,3 voltage more than required applied in digital multimeter?

Does it negatively affect if more 0,3v voltage than Power Supply (PS) required by general digital multimeter (DMM) supplied ?. I have a DMM with PS requirement of 2 x 1.5v AA battery and in hand is 2 ...
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2answers
383 views

Measure small voltages in a high voltage circuit

I'm troubleshooting an oscilloscope where the cathode voltage is ca. -2000V respect to ground and chassis. There are parts of the circuit (eg. the heater filament, or the blanking / un-blanking ...
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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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2answers
733 views

I need explanation on some digital multimeter (DMM) specifications

What is digital multimeter (DMM) ranges reading; resistance : 400 ohm - 40 Mohm supposed to mean? would it mean the DMM cannot measure a material resistive property of less than 400 ohm ? And what ...
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3k views

Why are the 10A inputs on many multimeters unfused?

Most multimeters have a current measurement setting for low currents where a fuse is present. However, to measure high currents up to 10A, you need to use a second input that is often unfused. Now, I ...
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84 views

Beginner Q: Measuring current via USB charging cable

I was trying to use the multimeter to find out what current does my charging cable actually provides to the phone. How do I accomplish this without completely destroying my cable? Right now I can ...
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2answers
96 views

Need help interpreting a Energy Meter datasheet

I am reading this datasheet for an energy meter, to start understanding how this market works. A friend of mine wants to make a test in a small office building to see if it pays having one of these ...
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2answers
188 views

Is it possible for a digital multimeter to be modified to read 10 times the ac voltage?

I would like to modify a kit multimeter so the ac voltage can be read ten times larger for teaching purposes. The test bay has been set up on 24 V AC but I want the students to be able to read 240 ...
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1answer
74 views

How would you go about testing a USB cable for a short?

I have had an issue with a USB cable blowing up a device when plugging it in (pop, burning smell) assuming a resistor blew. I'm trying to figure out if this was caused by the cable or the port. If I ...
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2answers
137 views

What is this VU-meter?

I just made a "home made" adjustable power supply and I want to attach a voltmeter to the output so I can easily set voltage using a potentiometer. I don't want to complicate my circuit with a ...
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4answers
5k views

Measuring current with a multimeter - What did I do wrong?

I wanted to measure the current of a generic lithium ion battery charger. I set I plug my red lead in the A 10A max fused and black into COM. The charger is rated at 600 mA and my other lead plug ...
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1answer
7k views

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?
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230 views

modern replacement for dip meters?

Dip meters are no more manufactured (and old ones are no more calibrated). These devices were thought to be very useful to a large game of ham radio and electrical engineers. Usually, when a device ...
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2answers
860 views

Accuracy error of ammeter from specification : is it really just a constant offset?

On ammeter specifications it is often written accuracy specification $$ (....\% rdg+ ... digits) $$ While the ammeter can have a certain last digit on the screen, which determine the resolution if ...
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1answer
571 views

Problem in identifying positive and negative terminals of a capacitor

I have got a capacitor from a fan. The electrician says that it's not working, but I think he is lying. I want to test it with a multimeter. But I cannot understand which plates are positive or ...
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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 ...
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129 views

How to determine accuracy of multimeter?

I have two multimeter of local brand both work good but both have slightly different Reading. When i check it with 7805 ic voltage one says 4.91V and one says 5.12V. I know its very low differance but ...
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2answers
376 views

high resolution analog AC voltmeter mystery

I have an old Pekly multimeter that can be seen here. This is an analog multimeter, and only its Ohm-meter needs batteries. It can measure current intensities, DC and AC voltages, and resistances. The ...
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3answers
3k views

Why doesn't my multi-meter diode tester work on this LED?

I own a TENMA 72-7720 Multi-meter with LCD/continuity tester: I've used this on other LEDs to test, no problem, using the diode tester setting (approximately 2:00 on the dial by the hold button) I ...
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5answers
317 views

Measuring small current (<1mA) at high DC voltages (~30KV)

I was wondering whether I could use a simple multimeter to measure small currents (<1mA) at high DC voltages (~30KV). From a cursory internet search I got three answers which were repeated ad ...
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1answer
162 views

How to read USB voltage with my multi-meter? [closed]

I am a complete noobie (though built a disco light when I was a teen). I am trying to read voltage on a USB slot in my PC. I suspect it's supplying too much of it because it fried 2 USB devices (usb ...
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1answer
44 views

V-meter's value is stabilizing when measuring

I am curious about my V-meter behaviour. Sometimes when I measure voltage the voltage showed by V-meter is slowly dropping until it stabilizes after few seconds. And same for current, except current ...
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1answer
37 views

Current draw different results

I'm hoping somebody can shine a light on this crazy scenario that I can not get passed right now. I have a device that needs 3.6v to be powered on. When I put a 3.6 battery straight to the device, ...
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1answer
148 views

How can I measure total current used

I have a circuit that includes an arduino and an electromagnet thats periodically turned on. I can easily measure the current consumed when its turned on and when its off by wiring in my multimeter in ...
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3answers
399 views

Can a multimeter measuring current damage low voltage devices?

I'm using an arduino due (3.3V) which its power regulator can deliver 800mA of current. Can I connect a multimeter in series and get a reading of the current my circuit draws, and can i leave it ...
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2answers
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 ...
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3answers
91 views

Voltage measurement using the following circuit

I was given the following circuit for a mains-voltage measurement system. The oscilloscope in the schematic is meant to analyze a low voltage representation of the mains voltage supply. After ...
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1answer
417 views

Is this a cheap Chinese fuse or a current shunt?

I got this cheap DT-830B multimeter as a bonus when ordering stuff from a Chinese internet shop. I opened it up and was wondering if this is a fuse or a current shunt? Since the multimeter works out ...
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0answers
363 views

Unexpected results measuring AC from secondary of toroid transformer

I am trying to measure AC voltage from the secondary of a toroid power transformer, and I am baffled by what I am seeing. The AC measurement (less than 4 volts) is too low; the transformer is rated ...
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2answers
173 views

Why are the ADC and DMM readings different?

While doing an experiment we reached a conclusion which we wrote down as the DMM and the ADC reading being different. Now after doing some research It does confuse me as a DMM does contain an ADC of ...
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3answers
650 views

What does “AC frequency response : (60-1000)Hz” mean for multimeters?

I'm considering to buy a multimeter. The following is its specs as listed at Amazon: Size:KT6666 Featuring a wealth of functions, it is intended for troubleshooting various electrical issues arising ...
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1answer
75 views

Instrument(s) for measuring (and recording) temperature, voltage and current

I'm about to embark on a series of experiments regarding thermoelectricity. I am pretty new to instrumentation etc - though I played with electronics as a hobby, when I was a boy. I am starting to ...
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1answer
154 views

Measuring electric current in shield

I have noticed that there is some current (not dangerous levels) in the shield around the power supply in my computer. Would it be safe to measure the current (Amps) going through the shield with a ...
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2answers
4k views

Is voltage an accurate metric for testing the charge of an NiMH battery?

I regularly use rechargeable 1.2v AA NiMH batteries, and I'd like to be able to use my multimeter to test both how much charge they have when I've finished charging them, and how much charge they have ...
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1answer
292 views

How to measure the output level of the sub out of an A/V receiver

I want to measure the output level of the RCA subwoofer output jack of an A/V receiver. How do I do that? Should I use the DC Volt mode of my multimeter and stick the positive prove into the hole of ...
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1answer
295 views

Varying resistance on same types of capacitors

Just tried to troubleshoot the following pcb I am checking the capacitors first, none of them have any marks of them so I'm using my multimeter to check their resistance. (I've checked online and ...
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1answer
1k views

How do multimeters measure inductance?

I know that some multimeters measure capacitance by applying a constant current in a time Delta t, measuring the voltage difference before and after the current was applied, and solving I = C * (...
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2answers
4k views

How to test the voltage of a speed sensor and identify the +ve, ground and signal wires using a DMM?

I am a novice and would like to identify each of the wires going to a speed sensor. Below is a photo of the connector from the mainboard (left) to the sensor (right): Is it possible to identify ...
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0answers
156 views

Test a battery with diode test

I have just learnt how PN junction work, depletion region etc. And finally I got what actually multimeter's diode test is measuring. If there is potential difference between P and N material, and ...
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3answers
1k views

How to figure out if a 25V capacitor can replace 50V in this circuit

I'm following this video Astable 555 timer - 8-bit computer clock - part 1 where he builds this circuit: simulate this circuit – Schematic created using CircuitLab I just realized that the ...
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2answers
291 views

Digital multimeter - How does the wrong probe insert (input) alarm work?

I'm using a digital multimeter (UT61E) and it doesn't have the "Wrong Probe Insert" alarm feature. I mean when I select the Voltage Measurement with the knob but leave the probes in the Current ...
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5answers
3k views

Measuring the resistance of a real inductor?

Real inductors can be represented as perfect inductor plus a series resistance \$R_s\$. The impedance of this component is \$Z_{L+R_s}=R_s+j \omega L\$ therefore $$\frac{1}{Z_{L+R_s}}=\frac{1}{R_p}-\...
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1answer
80 views

Negative and positive electrodes on a battery - confusing results

We created a voltaic pile battery and tested voltage with a multimeter. Each cell is comprised of a penny and a nickel with wet paper in between (vinegar + salt solution). Then you simply connect ...
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2answers
1k views

How do I find internal resistance of multimeter, in both voltmeter and ammeter capabilities?

I was wondering how can I find internal resistance of multimeter, in both voltmeter and ammeter capabilities? I thought it was termed as input impedance but when I looked up the specs of multimeter, ...
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1answer
590 views

How can I make a DIY clamp sensor for my power meter project? [closed]

My aim is to make a power consumption data logger and analyzer that is non-intrusive and can be hooked anywhere to monitor the power consumption on that line. I've come across clamp sensors which uses ...
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4answers
771 views

How to know if a multimeter is defective?

One of our service engineers asked me(or tested me) how to know if an analog multimeter is defective without measuring any current, voltage or resistance. Just by looking at the device itself. Do you ...
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2answers
549 views

Can I measure the relative output gain of a power amplifier with a multimeter?

If I wanted to measure the gain that a power amplifier provides to a signal with a multimeter, do I simply do the following: Measure the input signal's voltage e.g. 1 Vrms Turn the amplifier up to ...
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1answer
2k views

Multimeter current measurement: internal resistance or input impedance specification

As the internal resistance (or input impedance) of a multimeter influences the circuit you are measuring, and therefore influences the reliability of you measurement, it would make sense to me to if ...