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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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40 views

Is this transformer working?

I found this transformer and I am not sure if it is working. I am confused with the multimeter readings. For example: when I am using the buzzer option to check the connectivity it buzzes when I ...
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1answer
145 views

Meter fuse availability/substitution conundrum

I own a Brymen BM235 multimeter, among other test instruments. While it's a nice multimeter, I have one problem with it: the fuse for the mA jack is a Siba 7017240.0,4, and nobody even bothers with ...
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69 views

Seared my circuit while checking voltage [on hold]

I was attempting to diagnose a problem with my dvd player as I was not getting any power, I wanted to use my multi-meter to see where the circuit was shorting out, I set the setting on the multi-meter ...
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1k views

Why do LCR meter manufacturers give the details of measurement frequency to us?

When you want to purchase a DMM, more probably you don't see at what frequency the DMM you considered would work, but in the situation you're considering to purchase an LCR meter, manufacturers give ...
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1answer
53 views

Measuring USB power adapter quality using multimeter

I have heard horror stories about poor quality USB power adapter. I have a collection of no less than 20 USB power adapters, most are from cell phone manufacturers and some from small projects. I ...
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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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1answer
3k views

Microphone voltage output - is it AC?

Can anyone tell me if the output voltage of a microphone (like the type on a webcam) is an AC voltage? And whatever it is, can it be measured on a standard voltmeter? Thank you.
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39 views

Continuity testing - Why does swapping DMM probes give differing results?

Continuity query - Can anyone explain this? Circuit is a simple 12v DC, wired as follows -battery pos to bulb to spst switch back to battery earth. Testing with DMM in the dedicated audible ...
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69 views

Darlington Transistor TIP142 same type but different values

I have a bunch of Darlington NPN Transistors TIP142 that are removed from two separate identical boards. The 1st one have the TO−218 CASE (left side of the image) and the 2nd the TO−247 CASE (right ...
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2answers
53 views

CB blew when trying to measure the current using multi meter. What went wrong?

I set my multimeter like this. Plug the black lead to the short tab of NEMA5-15 receptacle first and the red lead to the long tab. The moment I put the red lead in, there was a big spark. The ...
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2answers
181 views

DC current consumption with sense resistor, different measure on oscilloscope and multimeter

I'm doing low side current measurement over a 0.1ohm resistance. Load is a DC motor powered with 12V. Cable length between resitor and power supply ground ~60cm I get a voltage of : 75mV => 750mA ...
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1answer
604 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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111 views

Can I use any HV Probe for a Voltmeter/Ampmeter gauge?

I purchased the multimeter pictured below for a high voltage power supply I'm working on. It's rated for 100V DC and 10A, but I hope to measure several thousand volts. Is it possible to use a HV ...
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3answers
86 views

how to avoid brownout caused by a multimeter on esp32

I am using the VOLTCRAFT VC130 multimeter for measurement of current through my esp32. The microcontroller runs perfectly with two 1.5V batteries(~3V as read by multimeter in voltage mode). But when I ...
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3answers
98 views

What is line to line voltage supposed to meter at?

I'm pretty new to this but I know that in three phase power, when I'm metering line to line its usually at 208V, but I've been told that line to line meters at 240V. I don't know what would cause for ...
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805 views

Is a multimeter with 1,200,000 counts actually a 6½ digit multimeter?

The Keysight 34465A Digital Multimeter is specified as a 6½ digit multimeter. However, the meter is actually a 1,200,000 counts meter, since the meter wraps at 1.2, so if measuring a 1.19 kOhm ...
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1answer
59 views

How can I make my measurements of full-wave rectified AC using an A/D match a Fluke meter on its DC range?

I am trying to measure the DC voltage of a full-wave rectified 60Hz AC signal using an A/D and have it match what a Fluke meter reads on its DC scale. My current approach is to take as many (16 bit) ...
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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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1answer
62 views

Which current can a multimeter measure for an indefinite duration?

It might vary, depending on multimeter. But if on a multimeter, there is printed "10A for 30sec. MAX every 15 min" or "20A for 15 sec (time unspecified)", below which approximate threshold is the ...
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40 views

What is the difference between voltage across battery and voltage across a resistor?

simulate this circuit – Schematic created using CircuitLab I am doing an experiment for a lab and I am confused as to what they are asking. They ask to measure the voltage across the battery, ...
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3answers
992 views

Measuring a small resistance, ~0.001 ohm

I have a low resistance resistor that I would like to use to measure the current through another circuit, but first I need to accurately determine its resistance. Its data sheet says it is 0.001 ohm +...
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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
2k 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 ...
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1answer
43 views

Trouble testing capacitor

I have a Radio Shack DMM (Cat #2200811). I'm trying to test a 100uf 16v electrolytic capacitor on the auto range capacitance setting. I tried it with a 30uf 160v cap. and it worked (measured as 29uf)...
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1answer
99 views

Is it safe to use my multimeter to test UK wall outlet voltage?

From the question it should be clear I'm no expert. Just want to learn. I have a digital multimeter. If I connect the multimeter to hot+ground & hot+neutral on the 240v 50hz (max ~30A) AC wall ...
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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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52 views

Did my multimeter corrupt the ROM/EEPROM in my TV remote?

So I got my first multimeter today... I understand the basics needed, but maybe I was a bit overzealous... My TV remote has 6 pins sticking out next to where the batteries go. I assume these are for ...
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27 views

Measuring MOSFET Voltages not adding up. Vgs /= GNDs - GNDg

I am measuring a power mosfet with a multimeter. The voltage at the source with respect to GND is ~291V. The voltage at the drain with respect to GND is ~16V. The P-type mosfet is rated for 250V, so I'...
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1answer
137 views

Measuring voltage 10 times every second with HP 34401A DMM

I'm trying to measure voltage continuously for a short time using the HP 34401A digital multimeter. To do this I have connected the DMM to my PC via RS-232. The PC is running Windows 10 and I use ...
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1answer
42 views

How to fix 4AA battery pack holder

I have a battery pack holder. I have tested the batteries with my multi meter. It appears that the ground and power wires on my pack holder are not working. Does this mean that the wires are not ...
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1answer
362 views

Checking continuity using multimeter

I have recently took MCU board and testing continuity across button. When board is not powered i.e; not executing code, continuity on button is as expected (i.e; diagonally opposite pins are not ...
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9answers
3k 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 ...
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95 views

How does the multimeter measure the voltage? [closed]

I am using the fluke 88 multimeter and I know this digital multimeter measure the voltage drops when measuring the current(ampere) in a series connection because the current flows into the multimeter(...
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4answers
107 views

Multimeter, outlet and a Spark: the question of simple Voltage measurement

So I got a TekPower TP4000ZC MultiMeter. (Image source) It has COM port and two red ports: V-Ohm-etc. set at 600V Max and 500mA Max Fused 10A red fused port. Unlike other multimeters, there are no ...
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42 views

Multimeter ammeter resistance increasing

Recently I have been doing some measurements with a multimeter on some new transformers for my company. Lately I have noticed the resistance of the multimeter in current mode (ammeter) has increased. ...
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97 views

Why do different resistors of the same power rating burn out / not burn out?

I have a circuit board for a small LED light, which comes with an annoying strobe mode. To disable this I have found that I can wire a resistor from a pin on a chip to ground and the LED will stay in ...
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1answer
296 views

Relation between internal resistance and chosen scale on analog/digital voltmeter/ammeter

On Introductory Circuit Analysis of Boylestad I found out the following about the relation of internal resistance of a multimeter with the scale choosen on the instrument. Analog voltmeter: internal ...
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91 views

Voltmeter showing incorrect value when reading 12V battery

I'm building a battery box from a 75 AH deep cycle AGM battery, I have installed a voltmeter, but for some reason it doesn't display the correct value. I measured the volt with a multimeter directly ...
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68 views

Testing function generator with multimeter

I bought a used signal generator today. I want to check if it works with no problem but I don't have access to an oscilloscope right now. I have a multimeter that can measure dc and ac voltage and ...
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1answer
83 views

Using Voltage Regulator (9v to 5v)

I’m trying to ‘hack’ a LED Fire-effect light bulb to work on a 9v battery. Using a multimeter I can see that the bulb converts mains voltage to 5v. I’ve got my hands on a 9v-to-5v voltage regulator ...
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1answer
53 views

How to know voltage used on a data bus?

How do you find out what voltage is being used on a data bus for the high signal? On a small electronics I guess you can assume it will be 3.3v or 5v but what about other circuits, say in a car or on ...
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15k views

Why does a multimeter show VAC on VDC power supply output?

I used my simple digital multimeter to measure the real output of several small PSU's I have got at home. They all should give just direct current and show some values in VDC mode, but the multimeter ...
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1answer
41 views

Discriminate MOS from BJT easily

I have a transistor for which no datasheet is available the transistor is supposed to be NPN (which implies BJT). (BD247C-Transistor-NPN, 100V 25A, 120W in TO220) how can I find out easily if it's ...
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1answer
113 views

How to test transistor with Built-In Biasing Resistors

On a GPS device pcb, I found a small smd component that is marked as "22p V2". I found (tell me if I am wrong here) that it is a transistor like DDTA144WCA-7-F SOT-23-3 package, with built in biasing ...
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2answers
69 views

Why does this resistor network simulate differently from the physical package?

I am trying to simulate a Bourns 4310R-R2R-104 dual terminator 104 circuit resistor network. According to the datasheet, the circuit looks like this: When I read the resistance between pin 1 and pin ...
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29 views

Measuring (I vs. t) and (V vs. t) during welding

I am welding two plates using TIG machine welding. Before start welding I adjust the current value (i.e. 200 A) and voltage is 20 V. But, the real values of current and voltage will be changed when ...
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35 views

Mistakenly performed continuity test when power is on

I forgot to turn off the power of system before I did some continuity test using a multimeter. Basically an +-V dual supply was powering a transducer. Transducer was outputting very small offset like ...
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1answer
61 views

Any way to use external power for multi-meter instead of the 9V battery?

I have read discussions on NOT to use external power, say an ac adapter, instead of the 9V battery. But what if I mostly do is to test for continuity, would it be acceptable in such case? What other ...
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1answer
221 views

Why do I measure 5V in this circuit when I should measure 3.3V?

I have an audio processor board that has a 5V -> 3.3V LDO. For some very strange reason, when I measure the voltage of the output of the LDO, I read 5 instead of 3.3V -- which by the way is a lethal ...
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2answers
92 views

My multimeter probes are too big to measure a laptop battery

I'm having laptop battery problems, and the hardware manual gave diagnostic instructions involving measuring the voltage in the battery. So I bought a multimeter (never used one before in my life) and ...