Questions tagged [current-measurement]

Measurements of the current flowing through a circuit

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55 votes
7 answers
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What is the usage of Zero Ohm & MiliOhm Resistor?

I am new to PCB design and I noticed that some schematics use 0Ω or 100mΩ resistors. What is their purpose and why do we need to use them in our PCB design? Normally if we wish to probe how much ...
Dennis's user avatar
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3 votes
2 answers
4k views

What's the most economical way to digitally measure 240V mains voltage, current and power factor?

I'm looking to capture and analyse measurements of the mains energy that I use per circuit. I've found a few consumer products that offer powerpoint energy monitoring such as the Kill-A-Watt, but PC ...
i336_'s user avatar
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14 votes
5 answers
12k views

How to Measure Power Consumption on Extremely Low Power Devices?

This might be old news in a half a decade or two but by today's means, I am referring to electronic prototypes and designs which would draw in a μA (uA) and even nA range of current. Some recent MCUs,...
Mehrad's user avatar
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33 votes
7 answers
36k views

How do I calculate the power rating for zero-ohm resistors?

Based on my earlier question, since there supposed to be zero voltage (V=IR) drop across a 0 Ω resistor, how do we select the power rating of such a component? For example, let's say I were to ...
Dennis's user avatar
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0 votes
2 answers
599 views

Ordinary Differential Relay Problem

The answer given in my workbook to the above problem is A. The things I was able to point out secondary c-phase current = 300A and other secondary phase currents = 0A since the entire current ...
Nikhil Kashyap's user avatar
21 votes
3 answers
117k views

What value does ammeter or voltmeter measures (RMS, Average or Peak )?

What value does these meters measure? Is it RMS, Average or Peak value ?
Arun M's user avatar
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15 votes
2 answers
8k views

Why don't hall effect current sensors exist for low currents?

There do not seem to be hall effect current senors available for small currents, say on the order of 500mA. I'm guessing this is due to some technical or physical limitation. What is it?
Phil Frost's user avatar
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6 votes
2 answers
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Measure current in high voltage (10kV)

In a plasma application (Helium or Argon Plasma), we would like to measure the current. The voltage is around 10kV AC and modulated with a function generator. Currently we only have one of those ...
Martin H's user avatar
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5 votes
1 answer
401 views

How to measure supply currents ranging from 1μA to 10mA?

I’m building a battery powered data logger with a microcontroller and several sensors. I’d like to measure the supply current of individual parts with idle currents in the μA range and peak currents ...
Michael's user avatar
  • 883
4 votes
2 answers
4k views

How do I design a current transformer?

I want to make a Current transformer using toroidal ferrites to measure 220/50-60Hz AC current(40A max). Is it possible? And how can I calculate secondary turns count? Ferrite properties: H = 2000, ...
Edward's user avatar
  • 165
0 votes
3 answers
669 views

Why is my multimeter stopping device from booting when measuring current?

I am using a BK Precision 2709B multimeter and attempting to measure the current of a device that runs off of a ~3.7V battery. The device boots up, initializes and then goes into its lower power state....
Sean's user avatar
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61 votes
6 answers
20k views

Why am I not dead after repeatedly touching a high-voltage source?

While playing with mosquito racket in my home, I unscrewed the racket and touched the 2 wires with my hands. I felt that my bones were dislocated, I got shocked, but I am not dead. My calculations ...
pankaj prasad's user avatar
16 votes
1 answer
2k views

Why use an input resistor in this current sense circuit?

In the Linear Technology AN 105 on current sensing one can find the following circuit. I am wondering what the purpose of the 200 ohm resistor on the inverting input is. It appears to have no effect. ...
Max's user avatar
  • 193
13 votes
8 answers
3k views

Measure wide range of current 800 µA - 1.5 A

I am having difficulty measuring current into an IoT device that I am making. I need to be able to gather data about power consumption over time, and about the sleep mode current. I was trying to use ...
Reid's user avatar
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12 votes
4 answers
35k views

How does a non contact voltage tester work?

How does a non contact voltage tester pen detect voltages and/or currents? Are they limited to voltages of a certain range or type (AC or DC)? Here's some experiments I have conducted that lead to ...
JWVincent's user avatar
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8 votes
3 answers
2k views

Why is my circuit's current far lower than expected with 2.6v / 220Ohm / and LED?

I have a very simple circuit which I have measured the current to be only 3mA but should be in the range of 18mA. I have a simple circuit using 2 AA batteries (NiMH) at 1.3V each in series for a total ...
raddevus's user avatar
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8 votes
1 answer
3k views

Why shunt resistance has 3 line?

I know that the there is two lines to connect it to the integrator like the below picture , so what the 3rd line do? how to use it? is it necessary?
xsari3x's user avatar
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6 votes
2 answers
19k views

How to build very low cost current transformer?

Im building low cost home energy monitoring system. I want to see how much energy is used by water heater, big water pump, kitchen equipment, lightning, computer. I would be awesome if I could measure ...
Kamil's user avatar
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6 votes
2 answers
262 views

Current measurement maximum time

On my multimeter I have two current measurement connection. One for the mA and one for the A. On the ampere one there's a time limitation but not on the mA one. Also they mention in the manual a kind ...
Emmanuel Istace's user avatar
4 votes
1 answer
3k views

What's the difference between a shunt resistor and a four-terminal resistor?

I want to know if the four-terminal resistor and the shunt resistor are the same. Is there another use for the four-terminal resistor except measuring current?
R Djorane's user avatar
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2 votes
1 answer
1k views

Device to detect current (for cable including hot, neutral, ground)

I am trying to determine if an electrical device is on in a non-invasive way using an arduino. My understanding is that devices like current transformers and Hall sensors must enclose only the hot or ...
Alex's user avatar
  • 123
2 votes
3 answers
555 views

Measuring Current in Combination Circuit with a Shunt

I've done a fair bit of looking/asking around for help with this but I'm struggling to come up with an answer .... I'd like to measure and record current in a circuit. There is a 12 VDC / 2 A power ...
RIz's user avatar
  • 21
2 votes
1 answer
8k views

Measuring uA current with DMM?

I'm wondering if anyone knows the accuracy of measuring uA current with a cheep (~25$) DMM? I need to measure some low power circuits (10-500uA) and I'm deciding whether I should get an analog uA ...
MadHatter's user avatar
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1 vote
1 answer
160 views

How To Connect Silver Wire Electrodes to Transimpendance Amplifier

As the title suggests, I need to connect silver electrode wires that are about 1 inch long and 1mm diameter (sticking rigidly out of a microfluidic cell) to a transimpedance amplifier. The problem is ...
Gerald Wilson's user avatar
1 vote
4 answers
2k views

Question on the relation between Transformer's primary and secondary coil current

Suppose I have a 12-0-12 1Amp step down transformer. The primary coil is connected to 220V AC. How is the current flow in primary coil impacted in following 3 scenarios: When no load connected to ...
sribasu's user avatar
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1 vote
1 answer
5k views

how to resolve LM358's huge error as a current sense differential amplifier

I've built a current sense differential amplifier that measures the voltage across a 1 Ohm resistor, to give me a reading for the current through it. I've connected it as follows, all resistors are ...
MAM's user avatar
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1 vote
3 answers
381 views

Current measurement over a fairly large range

A part of a circuit I'm building has the following components: simulate this circuit – Schematic created using CircuitLab For clarification, the transistor's base is being supplied with ...
user34920's user avatar
  • 1,902
30 votes
2 answers
18k views

What are the advantages of a shunt resistor vs. a hall effect sensor?

I'm constructing a boost converter, and I need to measure both the input current and the output current. Currents range anywhere from 25A to 200A, depending on the model. My controller is referenced ...
Stephen Collings's user avatar
22 votes
5 answers
32k views

What is the difference between burden resistor and a normal one?

I just came across the word 'Burden Resistor'. Is it any different from a normal resistor? If it is different, where can I possibly get one? Sparkfun hasn't got one listed. Any help is appreciated....
Daniel Euchar's user avatar
16 votes
6 answers
26k views

How to plot current in ngspice?

I wish to plot out the current and power in ngspice. In the case of voltage, for example, if I wanted to plot the voltage at node 1 I would use: plot v(1) ...
sj755's user avatar
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11 votes
2 answers
836 views

Do batteries last longer with constant current draw or spiky current draw?

Do batteries last longer with constant current draw or spiky current draw? Or, as is implied by the accepted answer to "Making a battery last a long time in a microcontroller circuit", do some ...
davidcary's user avatar
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11 votes
4 answers
7k views

Is current flowing backwards a bad thing?

In the circuit below: I find it awkward that the direction of the current on the 2V power supply is running opposite to the direction of the current on the 5V power supply. In the 5V power supply the ...
T555's user avatar
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10 votes
3 answers
2k views

How OPA333 withstand 400V bus without burning in this current sensing application?

I went through following app note, where OPA333 is used in 400V bus current sensing application, also i have seen current sensor which have term called common mode voltage, which is specify the max ...
kobi89's user avatar
  • 194
9 votes
1 answer
3k views

Why can't a multimeter measure its own current and voltage?

Well I finally obtained another multimeter, so now I have a Mastech MS8226T and a Ben Electronic M92A. I decided to measure at which voltages would the low battery warning appear and how much current ...
AndrejaKo's user avatar
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8 votes
2 answers
27k views

How to measure max current of a power supply

I have a 220V to 12V adapter. According to the adapter label, the max current can reach 1.5A. But I want to measure the max current it can reach without depending on the information written on the ...
Wuthian's user avatar
  • 257
8 votes
2 answers
12k views

Why does an ideal capacitor give rise to a rectangular cyclic voltammogram (CV)?

Many scientists are interested in developing supercapacitors, which have electrolyte rather than solid dielectric between the charged plates. In the field of electrochemistry, cyclic voltammetry (CV) ...
Andrew's user avatar
  • 175
8 votes
1 answer
4k views

Using a Shunt Resistor to measure current

Usually when we measure current, we have to break the circuit and place the ammeter in series. However, if we want to make it easy to measure current at various points in a permanent circuit(for ...
Ammar's user avatar
  • 491
7 votes
2 answers
830 views

Best way to calibrate ADC for current sense MOSFET

I'm using the infinion BTS6143 as a current switch and current measurement device in combination with an STM32 controller. The BTS6143 is an integrated MOSFET with internal charge pump and \$I_{sense}...
JavaForStarters's user avatar
7 votes
2 answers
3k views

Capacitor for current transformer measurement circuit

I want to measure an AC current with a current transformer and an arduino device. I found on a website (http://www.homautomation.org/2013/09/17/current-monitoring-with-non-invasive-sensor-and-arduino/)...
CPA's user avatar
  • 197
7 votes
2 answers
20k views

Calculating a burden resistor for a current transformer

Background: I follow a reference design for a single phase power meter (230 V, max 3 A). The below circuit is to measure current via a current transformer. A current transformer will be ...
Angs's user avatar
  • 3,295
7 votes
2 answers
296 views

AA cells depletion

Currently I have two AA cells in series powering a 3.0v bus line for my application.Recently I am finding that one of these AA cells gets completely dead before the other. What could be the possible ...
Elsa Adams's user avatar
7 votes
4 answers
2k views

High-bandwidth current measurement

We need to measure +-50Amps of current (PWM) on a PCB. We need the measurement to be isolated, so I thought of using an ACS758, and feeding its output to an ADC. However, this hall effect sensor is "...
SomethingBetter's user avatar
6 votes
3 answers
2k views

Current sense amplifier + op-amp buffer + ADC: Measuring down to 0 with a single supply

I'm thinking about current sensing with a high dynamic range (10 mA - 20 A) and using LTC6102 as a high-side current sense amp (the voltage would be 54.6 V max, a 13S6P Li-ion battery). ...
axk's user avatar
  • 817
6 votes
1 answer
8k views

How do I detect servo stall with an Arduino?

I am controlling a standard 5-volt servo with an Arduino with PWM. My objective is to rotate the servo until it physically gets stalled (feels resistance) and then stop. Then I want the Arduino to ...
solutionhacker's user avatar
6 votes
3 answers
2k views

Recommended Layout for Parallel Current Sensing Resistors

I'm working with 12V DC systems and high currents (up to ~40A). In order to meet the wattage and price requirements for my design, I'm using two parallel sense resistors. The IC I'm using for sensing ...
Jack's user avatar
  • 61
6 votes
1 answer
2k views

How is this ground fault circuit working?

I am having a difficult time understanding a few things in regards to the ground fault detection circuit below. I have found this circuit while investigating ground fault detection. I intend to build ...
Jason's user avatar
  • 1,933
5 votes
1 answer
502 views

Parasitic capacitor current of an inductor

I am doing a double pulse test on SiC MOSFETs from 100-800 V and current from 20-80 A. The schematic is shown below (the values are not correct though): In my first round of tests, I was getting a ...
Autobot's user avatar
  • 155
5 votes
1 answer
1k views

Current sensing at μA accuracy and ADC nonlinearity

Project context A battery-operated positioning device sends location information through GSM at regular intervals. Between the fixes, the device is in low-power mode. The battery is supposed to last ...
Kasdonchu's user avatar
  • 165
5 votes
2 answers
12k views

Best way to test a USB wall charger for output current

USB chargers are tricky. Or at least they are when you don't follow the standards. I have a device that uses 5V to charge a battery. The device has a USB socket, with the idea of connecting it to any ...
Joel Santos Rico's user avatar
5 votes
3 answers
1k views

Measuring input current of opamp

I want to measure the current that goes into a noninverting opamp input. I've setup my experiment as follows: I can't measure the voltage drop across the 10M (R1) resistor directly since my DMM has ...
miceuz's user avatar
  • 5,561