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Questions tagged [current-measurement]

Measurements of the current flowing through a circuit

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15 views

ST VNH7070 current sense specification

I don't understand the way ST specifies their current sense pin in the VNH7070 H-bridge motor driver, see the datasheet below. How do I know what the current Isense will be? Why does the voltage ...
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1answer
26 views

What is the predictable difference of the voltage drop between the V+ and V- lines on a shunt resistor?

I am making an electronic speed controller, and the half-bridge driver I am using has a built-in overcurrent protection feature. In order to utilize this feature, I have to supply the pin (a ...
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3answers
154 views

Current measurement with shunt

I need to measure pretty high currents (maximum 100A) flowing from one battery to another. I came up with a solution involving the measurement of the voltage drop across a shunt resistor. The supply I'...
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1answer
31 views

What's the easiest way to implement portable current measurement for a ~200W dc motor?

I'm tinkering with an electronic skateboard build and I'm looking for a way to do some current measurements "on-the-go". What's the easiest way to implement this? It wouldn't be a part of the final ...
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4answers
174 views

Understanding “Current Draw” in terms of “Ohm's Law”

I'm having trouble understanding Current Draw as it relates to Ohm's Law (V = IR). I have a power supply rated at 5V and 500mA. I'm trying to power a string of LED lights. According to my ...
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2answers
51 views

Arduino + Current Sensor -> Not always working

I am trying to measure power consumption of devices by using an TA12-200 power sensor with a Arduino Uno board. This sensor is using a 800 ohms resistor and a 1:2000 ratio. My measure to get mAh ...
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0answers
42 views

micro controller cant able to sense analog value (ADC input) from op amp output

I am trying to sense the current in my motor controller using shunt resistor and an op amp. Opp amp amplifies the voltage drop of the shunt resistor, multi meter shows the output voltage good. But ...
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0answers
66 views

measure 4-20 mA and also power from loop powered

we know to give a command to an actuator in instrumentation we use 4-20 mA loop power. for reading this 4-20 mA I used the circuit below.so the problem is if my circuit only consumes 3mA, how should ...
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2answers
77 views

Full wave rectification by opamp

I am trying to read a current waveform from a shunt resistor series with the power line. Using a full bridge rectifier, I got the following waveform: The waveform was sampled every 2 millisecond ...
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1answer
29 views

Current readings of Ammeter

I was trying to solve this problem (number 27) and as per the KCL equations I am getting that an infinite number of Ammeter readings are possible. I used KCL after taking the outer loop as the ...
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0answers
43 views

Unstable speed with A4964 BLDC controller

I am using an Allegro A4964 for controlling a BLDC micromotor. I have tuned the PID and all available parameters according to the documents available from Allegro. Problem: In the control modes I ...
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0answers
36 views

Precise current and voltage measurement

I do current and voltage measurement at the same time with a low side ayrton shunt resistor network and a high side voltage divider. I want to measure voltages up to 400V positive or negative. The ...
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4answers
61 views

LTspice - analyze current with varying resistance

I would like to graph current from V1 over varying resistance instead of voltage. Is there a way to do this?
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1answer
33 views

Best method to determine current in ESR meter

I've recently found the need for a ESR meter(My daughter and her boyfriend brought me 8 broken LED/LCD TVs and 6 have power problems). I also decided to go all out and build a full blown ESR meter. ...
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2answers
35 views

Rogowski coil current rating

Is there any relationship between sensitivity of rogowski coil and voltage rating of coaxial cable with it. For example if I just have the sensitivity of the coil and spec of coaxial cable, is there a ...
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1answer
63 views

Current calculation for circuit diagram

I am new to this field and need help calculating current I2 through voltage source 2. U1=1V U2=3V R=10 Ohm Unfortunately I have no clue how to calculate this. Would be so thankful for help!
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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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1answer
53 views

How to connect INA321 in order to measure current across a resistor?

I need to measure control over a resistor using an instrumentation amplifier. I am using INA321 but for some reason, it does not work. Here is my circuit: In this circuit, the output voltage is ...
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1answer
50 views

Switch current sense resistor: series or parallel?

I am building a device that measures current in various ranges. For this I want to switch in different current sense resistors. To do this I see two ways: the resistors in series or the resistors in ...
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2answers
64 views

Real-time measurement of motors' current draw for a mobile robot

Found an Arduino-compatible Voltage-Current Sensor; it could remove the need for a separate voltage sensor. Is there a more recommended method to continuously and simultaneously measure the current-...
3
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1answer
60 views

AD8217 High Side Current Sensor Output at Low Currents

I am using an AD8217 high side current sensor to measure currents up to 20A. It works as expected when testing with lower currents and sense resistors of 1\$ \Omega \$ and 0.3\$ \Omega \$ and ...
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4answers
1k views

Why are current probes so expensive?

I notice that clamp-type current meters range in price from a few dozen dollars to a few hundred, but current probes for oscilloscopes cost significantly more, with many close to $1000 and some well ...
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3answers
75 views

How Much Current is Usually Used with IR Transmitting LEDs, in Remote Controls?

If you take various Remote Controls from your home, such as for a TV, Audio System, TV Box, etc, and measure the current that is supplied to the IR LED in the remote, what would be common current ...
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1answer
81 views

Resistor values on a 12v 10a circuit with LT3045 LDO

I am currently working on a project that aims to provide 12v 10a in the final output. I am quite new to EE and wasn't quite sure if I have choose the correct resistors value as highlighted in the ...
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1answer
46 views

Correct way to ground components for solar panel measurement

I'm currently doing a project where I'm supposed to measure the current and the voltage from a solar panel and am unsure of how I should ground all the components in the circuit (since electrical ...
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2answers
124 views

Oscilloscope range affecting voltage reading

I am trying to measure the current usage of a device using an oscilloscope. Every second the device turns on for a few milliseconds and then goes back to sleep. I need to find how much current is ...
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1answer
83 views

Current sensing techniques in SMPS

I have gone through the following circuit provided by microchip technology and I get trouble in understanding the circuit circled in red the the image!! As I understood, this circuit is used as a ...
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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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1answer
60 views

Fast 5V DC power monitoring

I am designing a camera that is powered by a 5 V DC power line. I need to evaluate the peak power consumption of the device during image capture. At a pixel clock period of 40 microseconds I expect ...
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1answer
36 views

Help understanding amperage of DC motor and heat generation

I am diagnosing an issue in an automotive HVAC system and have been testing the blower motor. I would expect somewhere approximately 8A to 15A of current draw. I have test wired the motor with 14AWG ...
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0answers
75 views

Measuring a small distance via capacitance

I am interested in measuring a small \$d\$ between two objects shown below by measuring the capacitance between the Terminals denoted as T0 and T1: The distance \$d\$ is roughly 1mm +/- 0.5mm ...
1
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1answer
43 views

Why ACS712 is abruptly dropping its voltage output?

I have built a board as shown in the images and the schematic below. I know that according to the datasheet when no current is flowing through the ACS712 it should output something around 2.5V always. ...
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1answer
57 views

Measuring integrated current

I want to measure the amount of light striking a photodiode in a specific time window (about 1ms). In this window, we get \$10^6-10^7\$ photons, which get converted into electrons with about 80% ...
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1answer
107 views

DC Current Measurement (resolution of ~ 1 uA)

I haven't worked with electronics in a long time, and now have the task of measuring the power consumption of a low-power device I'm writing firmware for... When the device is drawing very little ...
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1answer
75 views

Does a common neutral between solar inverter and utility affect current measurement?

I have solar hybrid inverter at home that's connected to the mains using both, the line and neutral wires. However, to save the costs, I've connected the load to it using a common neutral i.e. I've ...
6
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3answers
625 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). ...
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2answers
68 views

Measuring Power across a dummy load - use voltage or current?

I have a high power 8Ω resistor dummy load (approximating a speaker) which is being driven from the output of an audio amplifier. I want to measure the power consumption and display the results on an ...
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0answers
91 views

Detecting both short and open circuit voice coils in coil driver

I'm building a voice coil driver for a science experiment. The coils are in an environment where both coil shorts and coil open circuits are common problems. I'd like to build in a fault indicator to ...
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0answers
86 views

Capacitor in the circuit - Bypass capacitor

I was trying to measure the supply current of a CAN transceiver during fault conditions, one thing which I noticed was that during CANH to GND(when the current consumption is supposed to be the ...
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0answers
55 views

Measure low AC Power consumption (oscilloscope? MCU?)

I would like to measure AC power consumption of devices such as AC/DC charger, AC LED bulb or an electric circuit in the main box of a house. However, their power consumption are quite low and the ...
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2answers
206 views

Circuitry to measure sub-nano ampere current [duplicate]

Is there a well known methodology to design a IC circuitry to measure sub-nano ampere or even pico ampere currents within a very short delay of nano seconds? The SNR could be assumed to be fairly good ...
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4answers
134 views

How to measure micro watts (uW) [duplicate]

In an extreme low power project (MCU+BLE SIP running on a CR2016 battery for year(s)) I would like to measure the power consumption under different environments/algorithms. What would be the correct ...
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0answers
53 views

20 kV 100 mA Voltage Current Sensor

like the title says, i need to measure 20 kV 100 mA line. For the voltage part i found this:http://www.koncar-mjt.hr/en/docs/koncarmjtEN/documents/61/1_0/Original.pdf and this:https://www.hivolt.de/...
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2answers
29 views

Use of UC3843BD1G for current measurement

I was trying to develop an accurate current measuring circuit. So I opened up a multimeter for some reference. In which I found this UC3843BD1G Current Mode PWM Controller. Can this chip help me in ...
3
votes
2answers
1k views

Current measurement op-amp calculation

I am trying to measure the current using sense resistor method. Low Side Current Sensing method: I am using shunt resistor in the low side, there will be a voltage drop across the resistor. Since ...
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1answer
164 views

5V Current Transducer to 3.3V Analog GPIO Input

I am trying to find 3.3V variant of the 5V Current Transducer LTS_25-NP but so far no success. Is it possible to interface this 5V analog output to 3.3V STM32F407 analog input GPIOs? Edit: I want to ...
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1answer
550 views

ESP32 using acs712 give wrong values

I'm trying to measure current with acs712 30A current sensor connecting to NodeMCU-32S but I'm getting wrong and unstable values. For zero current the ADC pin should read value of 2048 (esp has 12 bit ...
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2answers
61 views

Selection of External Current Transformer

simulate this circuit – Schematic created using CircuitLab I am designing a product for motor protection circuit. where I want to use customized external CT for application which gives me ...
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1answer
71 views

What will be the current flows through the following circuit?

I`m confusing to see a textbook there is no current flows through the 7 ohm resistor. But why? And what will be the total current flowing through the circuit?