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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 to Read Unipolar Square Waves on TRMS Multimeter

I'm trying to switch from reading my high-voltage unipolar square wave signal from a benchtop oscilloscope to a handheld multimeter, but I don't understand why my multimeter is giving the voltages it'...
asyndeton256's user avatar
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Tinkercad multimeter doesn't work [closed]

Measuring voltage and current in Tinkercad, tell me why the voltage does not change when connected in series and the current in the circuit does not change when connected in parallel.
Foma Loktionov's user avatar
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Current Measurement of a Brushless DC motor

I am trying to measure the current drawn by a brushless DC motor under load. This is to check if the propeller and the motor are a correct fit at the desired conditions (a range of rpm, say 0-8000rpm)....
Ahmed's user avatar
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While Identifying Transistor terminals with Multimeter diode mode, why does B-E junction yields a slightly higher forward voltage then B-C junction?

I've learned that multimeter produces a small current in the diode mode and then measures the voltage drop across the diode. So a high resistance should produce a high voltage difference. Since ...
Osama's user avatar
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What would cause an AC multimeter reading to change if you reverse the probes?

I'm measuring the voltage in to a thermostat. It's supposed to be AC. When I measure wire1 and wire2 with black and red probes I get 0VAC When I reverse the leads I get 1.8VAC How can that even happen?...
Clay Nichols's user avatar
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How does a multimeter measure small voltages without being connected to ground?

I have a multimeter powered by a 9 volt battery. I put it in AC voltage mode that allows me to measure 0.001 volts. I have the red probe connected and the black probe (common / ground) detached. When ...
CausingUnderflowsEverywhere's user avatar
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No voltage difference between driven MOSFET gate and floating drain/source

I'm measuring the voltage of a discrete MOSFET using a multimeter. The gate is connected to the output of a logic circuitry, while drain and source are floating. The voltage difference between drain/...
Darsh Oian's user avatar
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Error measuring the voltage with a multimeter?

When testing my batteries, I wanted to test the battery on my multimeter without taking it out because I wouldn't have other new 9v batteries if I did. But, it just displayed a 1 (which means an error)...
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Trying to understand (and mimic) the multimeter's interference with a circuit

I am trying to use a microcontroller to regulate the speed control of a sewing machine, rather than the foot pedal that normally serves this purpose. The pedal cord has 2 wires that connect it to the ...
Fitter Man's user avatar
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2 answers
70 views

Best tool for measuring short duration voltage/current?

I'm reusing a watering timer (Melnor 4-port) by removing the circuitry and using only the latching solenoid-driven valves with my own microcontroller. I'd like to determine exactly how much voltage/...
Akom's user avatar
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Measuring the resistance of an LED -> getting conflicting values

I couldn't find the resistance values for an LED so I tried to measure it and ended up much more confused than before: I have a plain (red) LED and initially I used a multimeter to measure the ...
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UNI-T UT181A question: what is confidence interval used in the datasheet?

So the question is: https://www.batronix.com/pdf/uni-t/UT181A-Manual-English.pdf The manual has So if you are measuring perfect 50 Hz source you have resolution 0.001 Hz the values are in interval ...
Валерий Заподовников's user avatar
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Determining if a multimeter will damage ICs - How to confirm?

I’m looking for a straightforward way to determine if a particular multimeter will damage sensitive electronics such as ICs. Specifically, let’s say I have a Fluke 117 multimeter and I am trying to ...
KRitiCal_m4ss's user avatar
4 votes
2 answers
219 views

Capacitance on floating terminals of a multimeter

Why does a multimeter show some capacitance when its terminal are not connected to any capacitor? My multimeter is showing 30pF. Does this imply that my multimeter is not calibrated properly or it is ...
Technaut's user avatar
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Why isn't tungsten used for multimeter probes?

Gold is considered the best multimeter probe tip (though disadvantages are that it comes off easily when rubbed and is expensive) since its surface hardly oxidizes when exposed to room-temperature air,...
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UT61E multimeter AC Voltage measurement issue

when i connect to AC 220V it start at 99 acv and drop to 70 or 60 which is wrong value for that AC..how can i fix this issue? i cleaned VR2 with some alcohol, rotate it, the voltage changed to +350 ...
pharaon's user avatar
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Measuring current with a multimeter around a closed circuit [closed]

A question from physics lab: Referring to the circuit you built to measure currents, what would happen if we completed our circuit with a wire and measured the current with the multimeter at the same ...
Dee's user avatar
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How does a process calibrator source a resistance? [closed]

I have a Fluke 743b Documenting Process Calibrator. It is capable of measuring and sourcing current, voltage, and resistance (and a few other things that are out of scope of this question). It has a ...
adamj537's user avatar
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Do industry true RMS volt meters use a transformer?

I'm trying to build a true RMS volt meter that plugs into my 120 RMS outlet. Since I want to do it safely, I'm using a very handy transformer (ZMPT101B AC voltage transformer module) that takes the ...
cj91's user avatar
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Are measurements of battery voltage enough to test its state of health?

What I mean is that I might have 3.5 battery voltage, and I rarely use it. Note: If I measure the voltage it shows 3.5, but is not the internal resistance changed decreasing the current? If that is ...
Ali's user avatar
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Why does a DC voltage float with respect to ground? [closed]

What is the reason for a floating DC voltage? Why does it start from half of the output voltage? Example: We have 1300 V Connect one multimeter probe to positive and the other probe to ground. The ...
Vivek 's user avatar
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1 answer
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Can diodes be tested successfully in situ? [closed]

I have tested a bunch of diodes in situ on a washing machine PCB. One comes back as expected with values of 0.6v and OL depending on testing direction. The rest show the same 0.6v in the expected ...
watsoft's user avatar
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34401A Remote Measurement Time

I am using an HP 34401A as an ADC for data acquisition. I am triggering the device within a 'for' loop in MATLAB, so that I can synchronize the measurement with a separate device. I am able to collect ...
nudge's user avatar
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Can I measure the internal termination resistance of a MIPI receiver?

This question is further to: How accurate are internal terminators on chips with high speed differential inputs?. I would like to measure the actual termination resistance inside one of these chips (...
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Resistance measurement with DMMs

I had one doubt regarding resistance measurement from multimeters. I cannot show the schematic because it is confidential but I have added a circuit diagram. It refers to a gate driver circuit. I am ...
Andr7's user avatar
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Why do I measure a voltage between me and the hot wire?

If I plug one lead of a multimeter to the outlet phase wire and the other lead to my hand, why does it show 100 V when I stand in carpet, and 150 V when I stand at pure floor? What causes that voltage?...
electrixx's user avatar
4 votes
1 answer
112 views

How do modern cheap multimeters survive a massive range of voltages?

I bought a little, rubbish multimeter for $2. If I set the voltage range to 200 millivolt, then stick the probes into a mains socket, all I'll see is "1" on the display indicating ...
SF.'s user avatar
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How can I measure the internal resistance of a thermoelectric generator?

How can I measure the internal resistance of a thermoelectric generator? Can I use a standard multimeter? I am using a TEC1-12706B thermoelectric generator. I tried to use a standard multimeter to ...
Phạm Sáng's user avatar
4 votes
5 answers
2k views

Why do different multimeters give me very different current measurements?

I was trying to calculate R_TH using an open-circuit voltage and a short-circuit current, and I am having trouble with the current measurement. I noticed that my calculated R_TH didn’t match my ...
Samantha Garcia's user avatar
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Multimeter won't read resistance

I have an issue with my digital multimeter (Flir DM66). It won't read resistance. I've tried reading dc voltage and continuity, both work fine. But when I try resistance, it shows 0.8 when touching ...
Lovely Noises's user avatar
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Testing thermocouple functionality

I am currently working on diagnosing the functionality of a thermocouple from a vintage gas stove, whose safety valve does not stay open with the pilot light heating the hot end of the thermocouple. ...
gothicsurf's user avatar
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SDM3055 injects 50Hz noise

I am performing some measurements on this circuit (simplified). Some details: Power supply is linear Circuit is mounted on a breadboard Oscilloscope connected using a ground spring Oscilloscope and ...
Fab's user avatar
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Do digital multimeters work the same in vacuum?

We want to use a RS14 Handheld Digital Multimeter inside a glovebox and therefore we submit it to vacuum (0.1 bar) to come in and out of it, and to inert N2 atmosphere once it is inside the box. Does ...
psansoldo's user avatar
1 vote
1 answer
53 views

Multimeter reading discrepancy on output of HV converter circuit

I am trying to measure the high DC voltage after it is converted from 5 V to 3 kV through the EMCO AG30 voltage converter. I set the PWM output from the Arduino to 255, so theoretically the voltage ...
Hao Gu's user avatar
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1 answer
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Question on testing transistor TIP120 NPN using multimeter

Could someone please help to confirm if these values for a TIP120 NPN transistor based on the diode setting of my multimeter, indicate any potential fault? Base (Positive) with Emitter (Negative): 0....
user21971539's user avatar
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2 answers
92 views

Multimeter Range and Resolution

I'm confused as to how my multimeter takes readings, especially since its not an auto-range multimeter. I have to switch to the desired range to carry out measurements. Unfortunately, the resolution ...
imran muhd's user avatar
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1 answer
158 views

18V battery charger showing hazardous voltage symbol on Fluke multimeter

I have this little drill battery charger and I was testing the contacts for output voltage with a Fluke 87V, and the result was "-0L" and was showing the hazardous voltage lightning bolt ...
wdbwdb1's user avatar
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1 answer
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Does measuring current with a multimeter in series affect battery life?

I have noticed that a lower-power device that I am testing is running out of power much sooner than it should. The device should last up to 2 years, however, it is running out of battery at the 5-...
Calco's user avatar
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2 votes
1 answer
147 views

Multimeter resistance measure repair

I have ancient multimeter, recently the resistance range shows very incorrect values (or nothing). I have schematics and started to analyze, but can not identify how the resistance measure works. ...
Peter Novotny's user avatar
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2 answers
504 views

Capacitance measurement mode on the multimeter

I have one more question related to my cheap Aneng SZ08 multimeter, which I've purchased recently and am discovering its capabilities. This question is related to the capacitance measurement mode. To ...
Gog's user avatar
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1000VCATIIII0A marking on my multimeter probes

I've purchased a cheap Aneng SZ08 multimeter recently and I'm learning how to use it. The one thing I've noticed is that the handles of my probes has two markings on two sides: one of them says: CE (...
Gog's user avatar
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2 answers
41 views

Using central heating pipe to detect neutral line with a multimeter

I'm exploring the capabilities of my cheap Aneng SZ08 multimiter, which I've recently purchased. I have a question related to the detection of a neutral line in the wall socket using a multimiter. ...
Gog's user avatar
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2 answers
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Is measuring 220v AC current from wall socket with multimeter safe?

I've purchased a cheap Aneng multimeter (model SZ08). Since I'm not an expert in electronics, I have some questions related to the usage of this device. For instance, I wonder if measuring 220v AC ...
Gog's user avatar
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How can I test IC LM2903 TSSOP8 with multimeter on the circuit board to see if it works?

I have IC LM2903 on broken circuit board, and I want to check it with multimeter. I'll be very thankful on any advice or answer. Images from ST LM2903 datasheet
Leo's user avatar
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Higher Resistance Measurement on Wet Tongue than Dry Tongue?

I'm trying to start learning about electrical engineering as a hobby. I'm reading from a book right now, and it suggests using my multimeter to measure the resistance of my tongue while it's wet and ...
verarox's user avatar
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2 answers
151 views

Troubleshooting inaccurate resistance readings in SMD resistors on PCB

My PCB has high-precision SMD resistors (0.01%, 25ppm/C) - some pre-installed, some I added. When I measured their values in-circuit with a multimeter directly at the pins, some of them showed ...
flower.fish's user avatar
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1 answer
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Connecting a multi meter across a single resistor

simulate this circuit – Schematic created using CircuitLab When I connect a multi meter to AB it shows 5V, but isn't the resistor supposed to decrease the voltage/current? V=IR (5 = I*1000) ...
Dan's user avatar
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2 votes
1 answer
220 views

How can I check continuity longer than my probes?

I'm trying to sleuth out a wrongly wired connection on a small injection molding machine. I'm starting by verifying the connections match the diagrams from the manufacturer. However, some of the ...
Maxthecat's user avatar
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4 votes
2 answers
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Multimeter Negative Resistance

I have a Fluke 87V multimeter and sometimes when I measure some resistors (in power supply PCBs I saw it) it shows me negative value of resistance. Why this? It is some flaw of the multimeter or it ...
DarkKnight's user avatar
1 vote
1 answer
58 views

What result does digital multimeter show when measuring filtered AC V? Is it Vavg or Vrms of the ripple voltage? What's the formula to calculate? [closed]

Can somebody tell me what result does multimeter show when measuring filtered AC V? Is it V avg or V rms of the voltage ripple? And what's the formulas to calculate this?
Günter Guss's user avatar

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