Questions tagged [current-measurement]

Measurements of the current flowing through a circuit

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Designing a high voltage power supply controller [closed]

I'm going to design a high voltage power supply controller board with 8 channels that will be remotely controlled via Ethernet. I will use a microcontroller, DAC IC like MCP4922, then an analog switch ...
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Using CAT5 cable for low current, CTs in mains panel, and in general

I couldn't find anything searching on the internet, I suspect it's either because the question is so stupid it doesn't warrant an answer... But I don't know whether it's obviously not a problem or ...
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Why is the ACS712 VIOUT more stable with a current limiting resistor?

Below is my circuit for an ACS712 that is connected to a relay that joins to s capacitor bank: In the diagram I using two 5V power supply, one for relay module and one for (PIC, voltage reference, ...
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Is my ACS712 sensor showing normal characteristic?

I bought a new ACS712 current sensor. VIOUT to ground is 2.560 V under no load conditions. This is very accurate as my supply is 5.12 V. I plug in an old fluorescent tube that needs a ballast and ...
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Need to modify PZEM-004T 10A to 100A

I accidentally purchased PZEM-004T 10A instead of 100A version. I have spare CT transformer from 100A version. It is possible somehow to modify 10A version to be able to measure 100A? I can solder ...
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Why does the LED turn off when I try to measure current?

I have the following circuit: simulate this circuit – Schematic created using CircuitLab I'm trying to measure the current in it, which should be \$\frac{\text{5V}}{\text{220}\Omega} \approx 22 ...
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Resistive current sensor shows reading when I connect it in series with a battery while no current is flowing through it

I need to monitor the charge and discharge current of two 12V lead-acid batteries in series using an INA219 current sensor, and a 0.75 mOhm shunt. At first, I placed the current shunt in the low side ...
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Add current limiter to this circuit

I made and built the following circuit. It measures current of an AC square wave of roughly ~19 V. The uController calculates a running average of 5 samples every millisecond. If the average exceeds ...
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Type of transformer needed to measure 4-20mA process current?

I occasionally work with 4-20mA process signals and need to read the current value flowing through the wire. I now use a standard Fluke 17B+ and must disconnect the loop and add the meter in series ...
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Current measurements for a DC motor being rectified when in reverse direction (differential low pass filter implementation)

Recently for a project I've been trying to capture voltage and current characteristics for a DC motor. To measure current, I'm using a single resistor (R1) in series with the motor, and feeding the ...
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Why doesn't my difference amplifier get saturated in LTSpice?

I'm currently simulating my high- side current sense amplifier for measuring mains current(along with the LP filter) .I also have the voltage sensing in the corner and I have attempted to simulate a ...
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How much smaller/bigger is ampere/second than miliampere/hour? [closed]

How much smaller/bigger is ampere/second than miliampere/hour? I want to check with people who know this way better than me at this.
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Voltage regulator consume more current

I have used LP3961 3.3V regulator cicuit for my STM32 microcontroller circuit. I have implemented low power stop mode in STM32. Micro controller consumed 25uA itself. When I Measured the current ...
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Removing 0A offset voltage from current sensor

I would like to use the CUI CS0312U current sensor in my application where its output voltage is fed into a non-inverting Schmitt Trigger circuit to realize a simple hysteresis current controller. A 1 ...
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Implementing A/D conversion circuit to a DIY clamp meter

I was looking for cheap clamp meter projects and found this one: DC non invasive current clamp for oscilloscope DIY. After reading about this project, I noticed that it had a BNC output to read values ...
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Measuring PoE power consumption with an oscope: Is PoE Ethernet non-grounded?

I have a need for measuring current (and thus power) delivered via Power over Ethernet. I have created a modified Ethernet cable by splicing shunt resistors into it already, but I'm unsure about the ...
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Measuring AC current with a current transformer and ADC

I'm looking at using a current transformer (CT) to measure 50hz sinusoidal AC current with a microcontroller's ADC. Is there a way to measure the RMS or average of an AC signal with good response ...
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Hall effect sensor output

I am planing to use an LF 510 -S / SP15LEM current transducer. I am expected to sense -300A to 300A. What is the output of the Hall effect? Is it mA or mV? If it is mA I will need a resistor to have a ...
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LED Current Draw Questions

I need a little help with understanding the current I'm working with. I have these LEDs, and trying to power them with an Arduino type board, a Wemos/Lolin D1 R1, based on an ESP8266. I measured the (...
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1 answer
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Why is one current reading ~20% higher than the other two in a balanced high-leg delta load?

We are using eGuage watthourmeters to monitor the outdoor unit on five VRF systems powered by two different 3P4W 120/208V high-leg delta panels. The neutral is not connected to the outdoor units. We ...
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Where To Connect Wires on Pin Out

I am very inexperienced in wiring. Where do I connect the wires from my trans-impedance amplifier to my DAQ to measure the voltage out and also to apply a voltage. I don't understand why there are ...
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How to test if current reading functionality on multimeter is working

I have a new multimeter that I've tested the voltage of a 12v flooded lead acid battery with before. Today I tried to test the amps running on the battery, to see if there was parasitic draw. As ...
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RF high power amp bias scheme

I am using the TGA2237-SM for the TX side in a front end design. I am trying to figure out an analog method for doing the bias up and bias down procedures. Bias up Set gate to Vg=-5V Increase Vg till ...
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How to input range of current values in LT Spice

Firstly, I'm a beginner at LT Spice. I wanted to learn how could you input a range of values for current. For example, let's say, I want my waveform to oscillate from 10uA to 10mA in the circuit below ...
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Is this op amp circuit a promising idea to measure 300VAC?

I need to measure 300VAC. I am using the following circuit and it is working good. In the circuit, I am using 2mA/2mA current transformer. More details about this transformer are available here. ...
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How do Fuel gauge ICs compensate for battery aging?

I came across this Fuel gauge IC recently and although I understand how the SOC is determined, I do not understand how the age compensation constant(the one used to determine the actual SOC) is ...
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Measuring the diode current

R1=15kΩ R2=40kΩ R3=40kΩ E=4V VI--> -8V<VI<8V. In this circuit, diodes D1 and D2 are the same model 1N4007 diodes. (Is=7.02767E-09, VJ=0.7) When I assume that D1 is on and D2 diode is off, ...
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5 answers
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Best way to measure current through LED with oscilloscope

I'm using the following circuit: simulate this circuit – Schematic created using CircuitLab What's the best way to measure the current through the LED with an oscilloscope? Because the ...
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4 answers
455 views

What is the lowest component cost way to detect ~50 mA current flow?

I'm looking for a method to detect when a power output connector is in use and I imagine the best way(?) to do this would be to monitor the current, which is guaranteed to be >50 mA @ 5 V. ...
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IV curve has non zero current in open circuit condition

I have an IV measurement program running in LabVIEW, where I measure the IV curve of a photovoltaic module using a programmable electronic load from a quick backward sweep (from Voc to Isc.) I have a ...
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High-side current sensor causing feedback oscillations during overcurrent

I'm trying to design a circuit which uses an INA138 current sensor to shut off a load during overcurrent conditions (max current = 1A). However, when the current is over 1A I'm creating a feedback ...
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1 answer
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Calculating Fuse Panel Wattage

I am trying to figure out how many watts my house is drawing. I used a clamp-on meter to measure the current on the hot leg of my fuse panel which showed 128.8A. I am then assuming 120V which gives me ...
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2 votes
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61 views

No current changes using INA219 to reading industrial sensor

I intended to use the INA219 chip to read the 4-20 mA current loop of the industrial sensor for the automation project. the sensor voltage is 12 V, my first schematic was as follows: The ground of ...
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Large signal current measurements of a loudspeaker

I'm trying to work out a method of measuring electrical current through a loudspeaker load for voltages in excess of +-20 V to be read by an audio interface - I need to scale down both voltage and ...
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How to accurately measure average temperature of a heating element?

Problem I'm trying to very accurately measure the heat of a nichrome wire as current is passed through it. My approach thus far has been to monitor current and voltage across the heating element and ...
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1 answer
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How to connect a 2 wire current sensor to a 3-wire set-up?

At the moment I have a couple of 3 wire current(4-20mA) sensors inside my setup that have the same connection as the schematic below. One of the sensors has broken. We can not directly get the same ...
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What is the purpose of this block in UC2854 based PFC circuits?

Below is a snippet from the datasheet of UC2854. Current transformer senses the input current of PFC. But Rs also does the same. What is the square block shown here?
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Trying to alternate power supplies seamlessly when a certain current threshold is hit?

I don't know much about electronics so asking the right questions is troublesome sorry about that. I need to swap from a 1S Li-Ion battery with cylindrical cells 3.8v to a 1S Li-ion battery with pouch ...
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1 answer
247 views

What is the advantage of servoing instead of directly measure?

I was looking at the LT6118 datasheet, since the TI amps (like te INA381) I am used to are not available. They mostly do the same thing, and probably are intended as direct competitors, IMHO. The job ...
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Current transformer with no load?

The apartment complex I’m in is only a year old, so we’re still in the Defect period with the builders. I’m on the Committee of the Owners Corporation, so I get to see the utility areas. The builders ...
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What's an easy way/circuit/load to visualize current (PWM)

I have a system that modulates PWM current output, and for a demo targeted at a general audience, I want to show that the duty cycle of the output is being modulated. The easy way to do this would be ...
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Current sense resistor vs transimpedance amp vs hall effect current sensor for instrumentation?

I'm using a photomultiplier tube; this creates a current output relative to the number of photons incident to it, on the magnitude of microamps. So, I need a precise and accurate way of measuring very ...
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1 answer
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4-20ma current loop and ESP32 [closed]

Following a previous question I'm thinking of using the following design for a 4-20ma 24VDC preasure sensor with an ESP32 ADC pin Will it actually work? Should I add aditional protection like two ...
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1 answer
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Is AC current clamp meter accuracy affected by the inner wire curving around the outside?

I have a SCT013-030 current clamp sensor I plan to use to read out the power usage of a mains AC load. It works by wrapping around one of the AC strands of wire to measure the magnetic field. The one ...
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1 vote
2 answers
102 views

Using two op-amps to measure the current in a predefined window

I've been trying to use an op-amp to measure the current and then use two op-amps as a comparator to detect the whether the measured current is within a window. The circuit defines the upper and lower ...
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1 answer
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Measure AC (24VAC) current with 3.3 MCU

I'm trying to use the following circuit designed by someone else : VCC = 3.3V It's aparently adapted from this one: Taken from : https://github.com/OpenSprinkler/OpenSprinkler-Hardware/tree/master/...
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2 answers
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4-20 mA current loop with a 3.3 V microcontroller

I have an analog pressure sensor that I am trying to read. The sensor is powered by 24 V and outputs a 4-20 mA signal. I want to connect it to an ADC pin of a 3.3 V micro. There are two designs I'm ...
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How To Connect Electrodes to Transimpedance Amplifier? [duplicate]

I wrote a post earlier last week asking the same question, but I have better information now. I have a microfluidic cell with silver electrodes with 1mm diameter and about an inch long. I need to ...
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1 answer
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Why is this oscillating / Why is shunt voltage undershooting so much

I'm building a circuit to switch shunt resistors to keep the shunt voltage within 0~100mV. The idea is to measure current over a larger dynamic range while keeping the burden voltage low. It does this ...
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1 answer
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How to get current value from a current transformer voltage reading value

Given the simplified current transformer setup and a transformer with 100 A : 50 mA ratio, how would I calculate back the actual current given a voltage reading on the ADC? simulate this circuit &...
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