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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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4answers
78 views

Solar cell outputs full voltage but barely any amps

So I've asked a similar question in the past, but I'm still curious about something. On a fully sunny day, the solar panel tops out at 5.5v @ 260 mA. On overcast or cloudy days, the voltage stays ...
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3answers
119 views

How do digital multimeters measure capacitance?

How do digital mulitimeters (DMM) measure capacitance through their typical 10M Ohm input/output impedance? Providing a logic level of 3.3V, attempting to measure 1F would mean a time constant of ...
5
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2answers
1k views

Why can't I get a resistance reading on my temperature probe?

I'm a complete beginner to electrical engineering, so I think I might be doing something stupid here. I have a set of grill temperature probes I ordered from Amazon. I am trying to find out the ...
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3answers
72 views

What does DC voltage reading from a DMM mean?

When a DMM is set to measure DC voltage, does a read-out value correspond to an output of the ADC inside the DMM, or do multiple ADC outputs are averaged over a time interval and then converted to the ...
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1answer
190 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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2answers
285 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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2answers
58 views

multimeter, current measurement (beginner)

From this little circuit I try to calculate the current for Ic, Ib, Ie. For Ic , I put the multimeter on 20mA and positive wire connected to 10A and I got 0.01 ... 10mA ? for Ie it is the same (Ie = ...
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3answers
37 views

How to measure current in very low duty cycle circuit with DMM?

My circuit has 4Hz 50% duty cycle. How do I measure the average current using a DMM? I have a Fluke 87 DMM. It has an average setting but for 100 ms which less than one complete duty cycle. My ...
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0answers
42 views

Why is there a positive body voltage when grounded, but none when not?

So after reading about earthing and earthing mats, I decided to make myself a very basic one for cheap to test the concept before jumping in with purchasing more sophisticated products. Here's what I ...
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3answers
147 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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3answers
2k views

What is the peak - peak voltage of 15mV rms white noise?

I've been experimenting with zener diode based noise sources. I have such a source for which I want to determine the peak to peak noise voltage. I've measured the noise with my trusty multimeter and ...
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3answers
621 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

How do I find the right resistor for an LED panel? [closed]

I purchased one of these cheap LED panels to light a room. One review suggested that it's important to put a resistor on it, to keep it from frying itself. But, he didn't list what resistor to use. ...
1
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1answer
70 views

LED intermittently fails but works when voltmeter applied

I have an LED in a home project. It's in a simple loop with a resistor and the GND and V+ ends connected to appropriate pins on a microcontroller. The LED works properly for extended periods of time ...
4
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3answers
222 views

Good equipments to measure current consumption for IoT devices [closed]

I was asked to bought some equipment to measure the current consumption for the IoT devices. The company is a startup and has a limited budget for this (let's say less than 5k$). I'm looking for an ...
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1answer
106 views

Resistance reading on digital multimeter

I'm working my way through a beginners electronics book (to be specific it's 'Starting Electronics' by Keith Brindley). I've got up to the second chapter which introduces resistors and their colour ...
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2answers
58 views

Diode meter of my DMM does work for red LEDs but not for white LEDs

I have a diode meter on my DMM Powerfix Profi and I want to measure the forward voltage. (actually it is not so profi at all). So I tried the steps needed, and found the Vforward of a red led to be 1....
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1answer
98 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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5answers
142 views

How can a multimeter measure current while being parallel to the element

An ammeter is a low resistance device connected in series with the element through which we want to measure current However, a multimeter is connected in parallel with the element under observation ...
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2answers
96 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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2answers
179 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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1answer
66 views

Can I use a multimeter to measure audio signals by testing amperage or voltage?

I'm in the process of adding a subwoofer to my car. In doing so I spliced in a T harness to audio wires from the head unit and routed the wiring to where I Will be placing the Amp. I tested the ...
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3answers
75 views

powering an old 9V multimeter with a 6x AA battery pack

I have an old Nimex NI2100 multimeter that is working fine with 9V batteries. Btw i'd like to power it with 6x AA batteries instead so i've bought a battery holder and wired like this: I've checked ...
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1answer
140 views

Why do two different multimeters show completely different resistance readings?

I just received a brand new Brymen 869s and I'm concerned it may be broken as it's giving a strange reading. When measuring a 100k 0603 resistor which is soldered into a PCB (forming part of a ...
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1answer
69 views

Ammeter scale, not sure what my amp reading is

I have a basic multi-meter that I am using to measure amp on a load. I am trying to figure out how much amps my small entertainment system draws. (LCD TV, PC, speakers.) I want to build a small DC ...
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2answers
102 views

Would I be able to use a rechargeable battery in a Fluke 87V (based on specifications)?

Would a Fluke 87V meter be able to run on a 9V Li-ion rechargeable battery capable of 550mAh? In general (for any device), what information (device specifications) would I need in the future in order ...
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3answers
2k views

Determine voltage drop over 10G resistors with cheap multimeter

I have two 10G resistors connected in series with a 3V battery. I want to determine the voltage drop across one of them, which of course is 1.5V. When I use my multimeter to check the voltage drop, it ...
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1answer
59 views

Measure voltage of the panel light bulb inside a vintage radio

I'm new to Electronics. I have recently received a vintage radio Pioneer TR-305. I am trying to replace the panel light bulb inside this radio. I opened the radio panel and found the bulb soldered ...
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2answers
111 views

Multimeter “false” measurement in car

Given my mom's car, I measured a voltage in an electric connector equal to the voltage across the car's battery. This is when the multimeter is connected to the connector supply pins. If I take the ...
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1answer
71 views

Wheatstone Bridge - strain gauge sensor

I'm trying to optimize a Wheatstone bridge with a strain gauge sensor and I'm considering all possible wire resistances. The circuit is shown in the following figure: I don't understand the comment ...
7
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5answers
16k 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
112 views

Current decrease in a lamp due to the change in scale of an analog ammeter

I do not understand what happens in the following situation regarding internal resistance of an analog ammeter. The internal resistance of analog ammeter changes if the scale is changed. For example ...
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2answers
64k views

How to check earthing using handheld digital multimeter?

I would like to know to how to check for earthing (electrical) ina house using handheld DMM.
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2answers
91 views

How to use a multimeter to test the resistance of my tongue?

I just purchased this cheap-o multimeter: https://www.amazon.com/AstroAI-Digital-Multimeter-Voltage-Tester/dp/B01ISAMUA6/ref=sr_1_1?keywords=astroai+am33d&qid=1551837071&s=gateway&sr=8-1 ...
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1answer
101 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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7answers
106k views

How should I use a multimeter to determine which AA batteries to keep and which to toss?

I have a bag of about 50 non-rechargeable AA batteries (1.5 V) that I have collected over the years. I bought a multimeter recently and would like to know the best way to test these batteries to ...
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2answers
31k views

What color is positive on a multimeter?

I bought a multimeter with attached leads. I would think red is positive but when I take a reading it only works if I use black as positive. Was it assembled wrong? There's nothing in the manual. It's ...
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3answers
17k views

Measure voltage difference between ground and DC floating power supply lines

110/220V AC to 12V DC switching mode power supply (metal enclosed, input is 220V with separate L,N and ground.) Measured voltage difference with a multimeter between V- and V+ 12V DC as expected ...
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1answer
124 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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1answer
68 views

Multimeter Giving Wrong Temperature Probe Readings [closed]

I want to ask a question about my multimeter, it's new but when i plug in the temperature cable - red to VOhm, black to COM and turn to tempreture it displays temp of period(-886°C/-900°C), and when i ...
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1answer
58 views

Circuit Failure How to fix it? [closed]

I'm sorry I am very specific here, I have a problem with the charger of my motorbike dashcam and I hope you can help me fixing it (see picture and video test with multimeter). I really have no idea ...
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2answers
127 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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3answers
120 views

multimeter temperature accuracy [duplicate]

I have tried searching for an answer and looked online, but I'm just getting more confused. I have a DMM that measures temperature with a thermocouple lead, with a resolution of 1 degree C (shows 020)...
2
votes
1answer
225 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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3answers
91 views

How to read a multimeter (digital) — should I get 2A readings from a couple of AA batteries?

I have been using some old multimeters in a high school science lab. We did a current an voltage reading from a AA supply (two batteries) with a variety of resistors. In some cases a 1M resistor. I ...
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1answer
823 views

Voltage sensing using Arduino with and without common reference

I wish to make a voltage sensing circuit (range -15V to +15V) using an Arduino's ADC. The problem is that since this circuit will be part of a much larger circuit in which the Arduino is performing ...
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1answer
219 views

Why can't I use lithium batteries in this multimeter?

I have essentially the same question as this. In that question, it seems lithium batteries are prohibited for use in the device because it wouldn't adequately warn the user that the batteries need to ...
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2answers
40 views

measuring resistance on hv transformer

I need to verify the resistance on a HV transformer that receives 208v single phase through terminal 1 and 2, or 240v through terminal 1 and 3 and delivers 4000v through terminal 4. As per the ...
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2answers
161 views

Testing crystal oscillator with multimeter crashes system

I have an old XT computer with a crystal oscillator that I would like to test. My multimeter has a Mhz setting that as far as I know should allow me to test it. (Providing the crystal is powered) ...
13
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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 ...