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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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82 views

Difference between using large vs small test resistance to check internal DMM/SCOPE resistance

For my intro lab to my Analog Electric Circuits class, one of the analysis questions is to calculate the internal resistances of the digital voltmeter and the oscilloscope, using the equation The ...
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123 views

Measuring wattage to PoE device - how to hook up a multimeter inline?

I'd like to measure the amount of power drawn by a PoE client device (PD) and would like to hook up a multimeter inline to do so. However, power is supplied to the PoE device over two pairs of wires (...
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117 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
168 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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1answer
63 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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1answer
49 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
75 views

Can you determine RGB pinouts with a multi meter?

I have a Swiftech Apogee XL2 that has an addressable LED inside it. I want to connect it to my other RGB setups but I need to know the pin signals and voltage of the LED. I have a multi-meter at the ...
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1k views

resistance measurement problem with digital multimeter

I accidentally caused a short circuit with DMM common lead while measuring 220 AC voltage. then when I tried to measure resistance it gives me a reading of 3500 ohm while there is no resistor ...
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75 views

Display input from multimeter on PC

I have opened a Multimeter (Model:DT830D) and I want to take the input that is fed to the LCD display and display it on my PC instead using the serial monitor of the arduino. But I am confused about ...
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52 views

Multimeter temperature coefficient - Specified accuracy

I want to calculate the temperature coefficient for a digital multimeter. The datasheet I read it is calculated as: 0.1*(specified accuracy)/°C (<18°C or >28°C) Do you know what specified ...
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68 views

Ammeter for 24V power that can be read by a Raspberry Pi?

I have a project I'm trying to design and build that involves a "more accurate/useful" battery gauge for an electric scooter. The scooter runs on 24V off of two AGM cells in series. The details of the ...
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1answer
59 views

How to determine which camera batteries will take the most photographs?

I recently bought a used digital camera, complete with 6 lithium-ion batteries. The batteries all have different date codes on them, but some of the older batteries seem to last longer than the ...
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1answer
71 views

Questions About My Solar Home System School Project

I have a battery, light bulbs, a solar charge controller, and a solar panel. The actual issue has come with me testing the solar panel. I have both a 30W and a 50W solar panel, so I am assuming the ...
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167 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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251 views

Innova 3320 multimeter calibration

Anyone have experience adjusting the Voltage reading on these? My less expensive meters have a single pot for calibrating, but this one has three. Labeled on the circuit board as V1, V2, and V3. I'd ...
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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
96 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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1answer
105 views

Ground loop current for voltmeter

I am trying to build a voltmeter, but the voltmeter is powered by a 12V dc adapter. My concern is if the ground potentials between the analog input source and the voltmeter are different (e.g. due to ...
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691 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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385 views

A DMM low current measurement question

I'm stuck with a question when reading a textbook: The question is a situation as follows: The very high internal resistance of digital multi-meters, in their voltage measuring ranges, can be used ...
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681 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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48 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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154 views

How can I measure the power given to a USB WiFi adapter's antenna in dBm or mW?

I have an Alfa AWUS036ACH USB WiFi adapter, and would like to know how much power is being given to the antennas (in dBm or mW). The Amazon link to it is here: https://www.amazon.com/Long-Range-Dual-...
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Multimeter shows 4.3V AC AND DC

Today I wanted o repair my door's buzzer system. After removing the front, there were a number of cables protruding from the wall. Pretty old building, so there was no clear color coding of the cables....
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Mulimeter Ripple Current Error

I have two multimeters. One is very good, the other one is quite cheap. I am measuring a regulated power supply to see if it is in indeed regulated. Both so 5.4 V, unloaded and loaded. This seems to ...
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420 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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1k views

Why are readings from multimeter leads are too high?

One of the multimeters I have is a cheap Craftsman 82140 65EA. Today I was using it and it was giving wildly high readings for everything. A battery that measured around 9V on a working multimeter ...
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41 views

Transformer, and Resistance Probelm

Is it possible to test the pins of a transformer using the resistance part of the multi-meter? I was testing a 6 pin transformer, and resistances measured 4.1 Ohms between two pins connected to a ...
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264 views

Supercapacitor ESR

I am trying to automate a method of testing the ESR of many super capacitors simultaneously. I have read that a good method of measuring the ESR of capacitors is to apply a square wave across the cap ...
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203 views

Do “True RMS” meters really do RMS if the input is a high frequency signal?

I'd like to measure the average of a signal which is mostly zero (less than a few nanovolts as best as I can tell) but may have occasional nonzero "blips" of maybe 20-100 nanoseconds (maybe 1V tall). ...
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408 views

Measuring the frequency of a 0-5V signal with DMM and no oscilloscope?

I'm trying to determine whether I can use a DMM to monitor a 0-5V signal of a cam and crank sensor. Both are magnetic. I have a 5V ref. The sensors should vary between 0V and 5V with a short pause ...
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79 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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52 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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40 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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79 views

Reverse Continuity Testing

I am interested in testing some low voltage cables for their quality. For example, USB, audio and Ethernet cables. Testing continuity is simple, but I want to know if these cables may momentarily ...
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96 views

Logic analyzer not shown signal

Good day. I am trying measure signal on ISO 9141 K-line - bidirectional serial link using logic analyzer. The device is Atmega based device with L9637 K-line driver chip. Problem is that, no signal ...
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Waveform monitoring on PC

I'm searching for a simple multimeter / oscilloscope simulation on Windows/Linux, which has the ability to import txt. or csv. datafiles and generate a video of an alternating voltage. I've been ...
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49 views

Continuity Testing

I have a fluke 381 and i was talking to another tech about testing voltage sensing fuses in a live Automatic Transfer Switch, the fuses are 2 Amp HRC type fuses and i made the comment that i have in ...
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46 views

On AC coupling DMM , does the DC part of the signal make a normal mode signal?

Suppose I want to measure the AC part of a signal using a AC coupling multimeter. Does the DC part of it (mean value) turn to be a normal mode signal?. Should a Normal mode be include in an error ...
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55 views

Moisture Sensor Resistance

I have made a soil moisture sensor by taking two lines of Veroboard and soldering a wire to each line. The theory is that the resistance will change with the moisture - resistance dropping as the ...
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54 views

Using a larger fuse in my multimeter

I am trying to replace the burned out fuse in my multimeter. It is very small with dimensions of 3.6mm X 10.25mm and has a rating of 600mA @ 250V. I can't seem to find this fuse. I can find one with ...
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179 views

What to use instead of 1k1 Ohm PTC thermistor?

I've got uni-t ut60a damaged. IC was replaced. Two tracks were repaired. The PTC thermistor of 1k1 Ohm is left. Unfortunately it is not easily available, in fact I couldn't find any of these being ...
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303 views

Is it possible to test capacitors on a logic board?

First, I would like to know if it is possible to test a capacitor while it is soldered to a logic board, or does it have to be unsoldered first? Second, is it possible to do so with a multimeter? ...
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2k views

How to test a schottky diode with a multimeter

I am trying to fix the backlight on an lcd monitor, I get the "2 seconds to black", the monitor is dell 23", and the inverter in built it the power board. I know caps are most of the time the ones to ...
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164 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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46 views

Should I get a multimeter to check size of voltage to avoid damaging a logic analyser?

I am looking into getting a Saleae logic analyser for a project to reverse engineer an electronic display and buttons for use with a RaspberryPi. I think it should be OK as I would doubt, by my own ...
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Multimeter shows too low voltage readings but everything else is mostly fine

I'm only asking if someone knows what might be the cause of my multimeter being broken. It is called DT-830LN. What's not working properly: The voltage reading is way too low, a 3.3V lithium battery ...
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173 views

MQ2 sensor VCC and GND continuity

If I use a multimeter on continuity mode and test my MQ2 sensor between the 5V and GND pins, I hear a beep. Is this normal behavior? If I set it to resistance, I get a reading of 40 ohms between the ...
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DT830B malfunction

I had this cheap multimeter (DT830B) laying around for some time, until its battery drop dead. After i changed the battery for a new one, then things got weird. The first test i did with it after i ...
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703 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 ...