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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Using reverse conduction on board repair

I am sorry if the title is misleading. As I am not a native speaker, I really don't know what the correct words to be used in the title. If you know the right words, please tell me so I can update the ...
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LED bulbs increasing measured AC line voltage?

I was troubleshooting an LED light flickering issue on a ceiling fan. Note the house is a partial knob and tube conversion with no grounds, switched neutrals etc. First I measured the voltage at the ...
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4 answers
922 views

How can a DMM measure open circuit voltage?

This question has bugged me for some time now. How can a DMM measure open circuit voltage? I have a general grasp of how ADCs work. How is an open circuit voltage measured when that should produce a ...
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How to test if current reading functionality on multimeter is working

I have a new multimeter that I've tested the voltage of a 12v flooded lead acid battery with before. Today I tried to test the amps running on the battery, to see if there was parasitic draw. As ...
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3 answers
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Is it normal that an analog voltmeter has about 7K ohm input impedance?

I have bought 10V 6c2 DC analog voltmeter, and I have tested it with a regulated DC power supply and it measured pretty accurately different voltages, however when I tried measuring the voltages in a ...
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What could the component be if the diode test result shows finite voltages for both orientations?

I was trying to identify a 2 terminal component using the diode test in DMM- It measured 0.420V in one direction and 1.88V in other direction. I am not sure what this component could be. For other ...
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What would cause an ohm meter to read .4 ohms when the leads are touching, but 0 when reading a short in a circuit?

I was talking to someone who does a lot of laptop board repair work and he was commenting that when he touches the leads of his meter together in OHM mode, he gets a reading of about .4 ohms ... which ...
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-1 votes
3 answers
97 views

Best socket for 2mm multimeter probe

I'm looking for a 2mm jack suitable for plugging a multimeter probe into (the probe end of the cable, not the meter end). I believe a 2mm banana jack would work and I've narrowed things down to two ...
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Have I been poisoned by lead dust from my blown fuse

just wondering if I've poisoned myself. I was doing something silly and the 10A fuse exploded in my multimeter with the glass cylinder and alloy dust shattering and splattering making a mess on the ...
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1 answer
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Help needed in understanding the lab observation regarding a diode

I was trying to understand the connections in a power supply board. It was found that anode of below diode is connected to GND and -ve terminal of bulk capacitor. Cathode of diode is connected to +ve ...
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3 votes
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Digital voltmeter reading half the voltage measured with Fluke multimeter

I recently purchased these cheap digital voltmeters from Amazon to display the output of my 2.5 kV HV supply. The HV supply has a dedicated 1/1000 output (0 - 2.5V)for monitoring, which I am trying to ...
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The Operation of multimeter [closed]

1.Does a multimeter operate With AC voltages? 2.What range of frequency does it operate?
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Using a multimeter to measure the VPP directly from an AWG output, how to?

tomorrow I'll have a lab class and we were told what we'll do in advance. So, since I don't want to be unprepared I started thinking about how to "solve" the problems, and I'm hardstuck at ...
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2 votes
1 answer
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Why does testing with multimeter fix my circuit issues?

I am using this heater along with this thermocouple and this amplifier and am just trying to be able to set and hold a consistent temperature. I have the heaters connected to a transistor circuit and ...
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1 answer
53 views

How to check ac current on ac adapter with dmm?

I tried by plugging the red cable into '10a' (measures current between some milliamps value to 10 amp, or so), and then putting black probe into the plug, then the red onto the jacket/outer part of ...
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1 vote
1 answer
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I can only read voltages <3V with my multimeter, why?

Some time ago I bought a multimeter from a not so known brand (I think): The LOMVUM T 18D. Below is the official product page: http://www.lomvum.com/pid18291854/T18A-B-C-D-E-Intelligent-Multimeter-...
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2 answers
140 views

Interpretation of multimeter displaying "OL"

Multimeters normally displaying "OL" when measuring resistance in ohms and the cables are not connected. My friend told me that apprentices in Germany learn it is "Overload", while ...
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Impossible current readings while measuring motorbike lamps

I own a motorbike that runs with a 6V (yes, 6V) electric system and I'm designing some LED lamps for it. My current design is dead simple, here is a falstad simulation, it's just two 1W 2.5V drop LEDs ...
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1 answer
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Noise when measuring OCV in a battery using Arduino and Adafruit ADC

I want to measure the Open Circuit Voltage of an electrochemical battery. When I measure this voltage using a multimeter, I get the measure correctly (around 1.12 V and without noise). However, when I ...
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-2 votes
1 answer
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Testing on an intercom amplifier

I am trying to test a door phone intercom amplifier. How can I test that the amplifier is not faulty with a multimeter. I have a tested fully working amplifier and another faulty one. If I measure the ...
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2 answers
183 views

Accuracy of analog multimeters

What accuracy should I expect from an analog multimeter that cost 50$ when measuring resistance? It's measuring 1.5 kilohm correctly, when measuring a 10 ohm resistor it's about 30% off. I tested it ...
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How to find what is eating up current in electronic circuit?

I have 2 exact electronic circuits, with one malfunctioning while the other is functioning. The total current consumed by the malfunctioning circuit is 0.48 A, while the functioning PCB has 0.271 A. ...
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Reading of ammeter

In my university, we are using these ammeters to measure current: What do the top series of numbers show (0-0.6/1.2), and what do the bottom series of numbers show (0-3/6)?
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5 answers
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Can I use 10A multimeter to test 445 watts solar panel

I want to know if I can use a cheap multimeter, model DT-830D, which has a maximum current rating of 10A to test voltage and amperage of a 445 watt solar panel with the following characteristics: <...
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3 votes
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Reading a couple of ohms when touching multimeter probes together

Around 10 months ago, I purchased a cheap-ish (~25$) hardware store multimeter: it's a K2M KDM-600C, 3.5 digits, 2000 counts. While messing around with resistance measurement on the smallest scale (...
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3 votes
1 answer
159 views

Can a DMM measuring voltage inject voltage?

Here are two behaviors that I cannot explain: I have an ESP8266-12F chip that is connected to an USB-TTL adapter (FTDI) through a breadboard. The adapter has TX and RX pins connected to RX and TX of ...
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Am I reading the multimeter uncertainty correctly? [duplicate]

I am using a multimeter that has an uncertainty (from the manual) of 0.5% plus 5 digits in DC voltage measurements, 4V range. I have a reading of 1.6172 V. That means an uncertainty of 0.508 V. Isn't ...
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1 answer
60 views

How to test the 5 terminal regulator with multimeter?

How do I test the 5 terminal regulator (e.g. LM2575) if it's defective or not with the help of multimeter?
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1 vote
1 answer
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Does CT act as a constant current source for a specific primary current?

I connected several resistors (1, 10, 100, 560 Ω) at the output of a 1000:1 CT (0-100 A measurement). I saw that the secondary current doesn't change for different resistors for a constant primary ...
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6 answers
239 views

Why is it not possible to measure PCB trace characteristic impedance using a multimeter?

I was looking into StackExchange posts for PCB trace impedance measurement. How to measure trace impedance? This posts clearly explains what the methods to be used for trace impedance measurement are. ...
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5 answers
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Huge difference between oscilloscope and multimeter

I am quite novice in electronics, but I have a great interest. I am analyzing an analog signal coming as input to a speaker. The purpose is to introduce that signal (after its corresponding leveling) ...
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Testing a Split Core Transformer based energy monitor circuit using a breadboard

I'm trying to validate my wiring for a variation of this circuit: which is taken from https://www.poweruc.pl/blogs/news/non-invasive-sensor-yhdc-sct013-000-ct-used-with-arduino-sct-013 Before I ...
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0 votes
2 answers
103 views

Multimeter kind of not working [closed]

Before I throw it out I thought I'd ask. I have a Craftsman 82141 multimeter that I bought 10+ years ago and never really used. I decided it was time to give up the Harbor Freight freebee now that I ...
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2 answers
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Oscilloscope or bench multi-meter for ultra high sensor sample rate measurement

I need a device to measure the output of a load cell at very high sample rates. I am aiming for a sample rate of at least 100 kHz. For this goal, I wanted to ask if it would be better to use a bench ...
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1 answer
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Mistakenly performed continuity test on the supply voltage (+12V). How can I determine if my multimeter was damaged? [duplicate]

I was testing continuity with ground in a breadboarded circuit and accidentally touched the supply rail (12V). My multimeter is a greenlee dm-820a. Everything seems to be working fine, but I am ...
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-2 votes
2 answers
89 views

Easiest way to make a resistor [closed]

What do I need to make a resistor of about 10 kΩ? After I make it, how do I measure the resistance with this device:
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13 votes
4 answers
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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 ...
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2 answers
212 views

Digital multimeter is reading erratic resistance ohm values

I have not come across this issue before in searches on this forum and searches on Google. I wonder if anyone else has come across it. My digital multimeter is unable to measure ohms. I'm just trying ...
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2 votes
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How do I destroy my multimeters?

During a task that involves current measurement in the mA and µA range, I managed to blow up the fuses of 3 DMMs. The DMMs were an old Voltcraft DMM from the 1990's, a PeakTech 2025 (similar to the ...
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4 votes
2 answers
2k views

How can I know if an IR LED (emitter) is working, other than using a smartphone camera?

I bought a lot of 5 mm, 940 nm IR LEDs like the picture below. I want to know if they are working or not. I tried the smartphone camera method, but I could not see the light. I have tested multiple of ...
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0 votes
4 answers
113 views

Measuring outside of multimeter range

While preparing a measuring setup for a project, I've realized that the multimeter our lab can provide only supports resistance measurements up to 10^8 Ohm. Since the materials we want to measure go ...
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8 votes
2 answers
869 views

Please help me debug my circuit

I am trying to build a guitar pedal but am unfortunately failing. I have about a high school physics understanding of electronic circuits, but the readings I am getting seem impossible to me. I might ...
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1 vote
1 answer
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How do I determine the actual measurement when the multimeter readings fluctuate?

The specifications of the multi meter state +/- 0.8% + 2. I will take that into consideration when I calculate the tolerance. But when I was recording values from the multimeter, I saw fluctuating ...
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0 votes
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111 views

How to check if L293D IC is working or not with a multimeter?

I know it is probably better to toss out a doubtful IC for a new one, but I would like to know if there is a way to check if the IC is faulty using a DMM.
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1 vote
1 answer
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Does the maximum voltage on a multimeter refer to the maximum difference between the two points or the difference between the points and ground?

I am trying to measure the current in a high voltage DC circuit (over 10 kV) and have an idea I think will work, but I want to make sure before I break equipment or create a dangerous situation due to ...
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What is the technical name for the "cap" on the multimeter probe's banana plug (or socket)?

Unlike the test leads that come with most portable, pocket size multimeters, the benchtop multimeter's test probe I had has a "cap" that sits tightly on and covers the banana plug. I'm ...
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Maximum input voltage to measure in multimeter/oscilloscope

I'm about to buy a Hantek 2D72 combined multimeter - oscilloscope. In the specs it says: Input: Maximum Input Voltage 150VRMS DMM: Maximum Input Voltage AC : 600V DC : 600V Maximum Input Current ...
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0 votes
3 answers
303 views

Why multimeter 10A fuse blew when measuring voltage? [closed]

Trying to figure out what happened to not make the same mistake. I was measuring if electricity is on or off on wires and with usual V port (600 mA) it showed weirdly huge number - above 1000, where ...
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1 vote
1 answer
281 views

Can I use a multimeter to verify if RX/TX of a device is working?

To summarize a problem: My electricity meter uses a HAN interface (via M-bus) to transmit the meter's data every 10 seconds. Apparently this HAN interface can be enabled/disabled by my energy provider....
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2 votes
2 answers
344 views

Identifying unique color code of non-inductive wire wound resistors: Weird resistor color coding, never seen before

Here we identify the color code determining the values of non-inductive wire wound resistors, specifically Yageo's NKN series (but applicable to other manufacturers of this class), which are a unique ...
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