# Questions tagged [current-measurement]

Measurements of the current flowing through a circuit

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

What value does these meters measure? Is it RMS, Average or Peak value ?
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### 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?
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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 ...
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### 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 ...
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### 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, ...
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### 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....
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### 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 ...
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### 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. ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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?
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### 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 ...
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### 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 ...
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### 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?
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### 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 ...
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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 ...
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### 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/)...
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### 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 ...
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### 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 ...
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### 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 "...
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### 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). ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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