# 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.

554 questions
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 = ...
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 ...
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 ...
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 ...
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 ...
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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### 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. ...
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 ...
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 ...
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 ...
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....
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 ...
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 ...
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 ...
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 (...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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.
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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)...
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 ...
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 ...
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 ...
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 ...
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 ...