Questions tagged [shunt]

Electrical shunt -- relating to a small resistance usually used to sense current. This is what your multimeter uses to measure current. This tag does not cover magnetic shunts.

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36 views

Hall effect current sensor ACS712 for battery application

I want to measure the current of 12V lead acid battery for charger application. So mostly, I need bidirectional current sensing.The current measurement can be done using shunt resistor or using hall ...
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49 views

Killswitch: switchable high voltage path/shunt to ground without any additional power supply

I have a circuit with a high voltage source (rectifet 400VAC) (part of a capacitor discharge ignition.) High voltage should only be available if normal power (low voltage DC power supply for the rest ...
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22 views

Load/Shunt resistor value calculation for DC-DC Converters

I have DC-DC converter with rating -4KV and 1W. The unit supports current monitoring of output voltage. I would like to test the current monitoring using shunt resistor. What should be the rating of ...
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29 views

current and voltage measurement circuits for battery [closed]

I want to measure battery voltage and current. Lead acid battery 12V. The supply of the lead acid battery is dc dc converter. Here I need to measure the voltage and current and should be given to the ...
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83 views

Very fast short circuit detection

I am working on a high current MOSFET switch project. I would like to implement short circuit/overcurrent protection, that would be fast enough to prevent MOSFETs from blowing up. In the actual ...
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2answers
93 views

Measuring high-side vs low-side current, different readings?

simulate this circuit – Schematic created using CircuitLab I'm measuring current consumption of several different handheld devices (calculators, flashlights, etc), at the [lithium] battery. ...
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36 views

How do you wire a transformer for multiple output and amperage?

I'm getting different answers watching the MOT (Microwave Oven Transformer) videos on YouTube. Some leave the shunt out, some leave it in, etc... I have a MOT and want to make a 12VDC power source ...
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1answer
62 views

How to measure shunt drop with an Arduino

I'm looking at a schematic like the following: simulate this circuit – Schematic created using CircuitLab I understand that this will be a very rough resolution as the drop will be in the 25 to ...
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31 views

Can I use two AD623 instrumentation amps on one shunt to cover broader current range?

I'm working on building a circuit with an ESP8266 module. I'd like to track its current consumption over time so I've cooked up a scheme to use a microcontroller dev board (Arduino or something ...
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65 views

What is the best way to parallel two shunt resistors using a switch?

What kind of switch in place of SW1 will have minimum amount of error in current readings? Max current is 10 A and we should be able to control the switch digitally. simulate this circuit – ...
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1answer
35 views

Determining the shunt resistance for DRV8301 BLDC Gate Driver

I am trying to study how to drive BLDC (Brushless DC) motors, and got stuck in the current-sensing part. I am using a DRV8301 Gate Driver IC, which contains with shunt amplifiers. My current ...
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1answer
69 views

Pulling down positive voltage to limit negative voltage current

Below circuit is the negative rail of a dual tracking power supply. How do I detect voltage drop on Node1 and pull down Node2 to limit the current without using an op-amp? Edit: I just want to define ...
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61 views

Relationship between speed against armature current/torque in DC shunt motor

I do not understand why the graph is like this as below when we use flux control method of DC shunt motor Also, can I change the x-axis of this graph to be armature current instead since equation of ...
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98 views

Why does my multimeter report a tiny current through a shunted 9-V battery?

Why does my multimeter report a tiny current (microamps, if that) through a shunt resistor (e.g., 1.5 kΩ) or even a short placed across the terminals of a new 9-V battery? The multimeter and all ...
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2answers
76 views

BLDC 3phase motor. The resistor 5W 0.1 ohm to ground very hot when motor working at 250Hz

Any one help me on this my issuse. I have a BLDC 3 phase motor controler similar to this Schem here encloses. When the motor working at 150Hz everything is ok. But if it is works at 250Hz then the ...
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1answer
63 views

Does a wide-band, high-current, inline ammeter circuit already exist?

I have an application where I would like to measure currents up to 1000 A, inline, but am also interested in using the same circuit for a low current part of the cycle. The thought is that if I can ...
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43 views

Which current types can be measured with a Shunt?

Which of the following current types are typically measured with the help of a shunt resistor? DC AC Impulses (4/10 us, 8/20 us, longer impulses > 500us?)
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20 views

Current sensing, clearance, trace width

I have to design simple PCB that will measure current by shunt resistor(R7, R8, R9) and voltage by divider. Board has 3xin and 3xout for different voltage/current specifications. I have the following ...
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87 views

Shunt Burn Issue

I've this schematic, where I'm blinking output bulbs (21W @ 12VDC). Rate of blinking is 85 counts/min. The wave comes to be of 700ms. On time 350ms. In this 350ms of On time, initially I skip 50~100ms ...
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69 views

Single shunt with multiple current sense amplifiers vs using multiple shunts

I would like to turn an Arduino clone into a current meter that allows me to measure the the power draw of a sensor node which has sleep and active modes. The sensor node's supply voltage is in the 4-...
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1k views

Is it practical to use relay contact resistance as a shunt?

I'm driving a DC motor and in its path is a relay with approximately 100m Ω contact resistance, can I use that resistance as a shunt resistor to measure the motor current? I don't want to measure the ...
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1answer
57 views

Isolated DC-DC common mode choke without shunt?

I was reading a page on the Recom site (https://recom-power.com/en/rec-n-very-low-noise-filter-for-isolated-dc!sdc-converters-46.html?3) where they devised a filter setup to achieve very low noise on ...
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239 views

The issues of common ground with voltmeter and ammeters

Apologies if this post is, yet again, another noob in electronics. I have an engineering degree in audio but have newly found a passion for electronics and am teaching myself as I go. I am trying to ...
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36 views

Comparator H Bridge current sense negative voltage input

I'm using lm339 basic comparator to sense current from an H Bridge. Current limiting was done somewhat successfully with acs712 after removing the capacitor from filter pin for limiting the bandwith. ...
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75 views

H Bridge vs Half Bridge current sense

Are there any disadvantages in measuring H Bridge current only via 1 shunt resistor? Since it will be made by hand on a perf board the only disadvantage will be the possible longer wires that connect ...
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1answer
49 views

Low Side Current Sensing Grounding Question

I recently made a low side current sense circuit to test a power supply. It works well, but I am trying to understand the strange behavior that happens when I apply the negative lead of my probe to ...
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1answer
89 views

ADC Measure from source with higher voltage and different ground

I would like to measure the voltage of a battery that varies from 4,5V to 3V. To do so I'm planning to connect this source to a STM32F4 DISCO board and one of its ADCs, which will be set to a VREF+ of ...
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1answer
73 views

Op Amp High Side Current Sensing

I'm trying to build a high-side current sensing circuit with a differential op-amp which can be seen below: The LT1006 is actually an LM358 IRL(I know it's a peanut op-amp, but it's what I have ...
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935 views

Why cap across shunt resistor, input bypass caps and small resistors on current sensing inputs?

I want to build a sensitive current sensing circuit using shunt, and since I also repair MacBooks occasionally, I have some contact with the schematics of real working expensive devices (although ...
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1answer
109 views

Microamp-milliamp Measuring Circuit: will my circuit work? Feedback/Advice

I'm developing a device which must be able to measure milliamps and microamps on one of its lines (down to 1 microamp, but also clearly seeing if it's less than 1uA). It's going to be DC of different ...
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44 views

Rectified DC current measurement using shunt or Current Transformer

I am working on a project to design a controller for battery charging solution. A 3 Phase delta power (440 Vrms ph to ph) is given to a 3-phase Variac Transformer ( Variac is operated ...
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59 views

What is the value of this shunt resistor from a drone power distribution board?

What is the value of the shunt resistor shown below? It is from the drone power distribution board, rated for up to 120 A. I am guessing, that the value is 0.25 mOhm. However, even with this value, at ...
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3answers
133 views

Non inverted OpAmp & Shunt circuit not working

I am trying to measure the output from a Hall effect sensor (LEM-LF 310-S) for a welding application. The maximum output of the sensor is 0-0.25A when sensing 0-500A. This range I need to convert to ...
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1answer
84 views

High Voltage DC - Shunt Resistor, Voltage Regulator Question

I'm a newbie here but was trying to wire a setup and was running into some issues attempting to calculate my required resistance, and resistor tolerance to current. I have a power supply that brings ...
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1answer
149 views

Current sense op-amp with integrated shunt vs expensive resistor

To simplify my question lets assume: I need to convert +/-7.07A RMS AC current into +/-707mV RMS voltage with high acurracy (0.1% or better). It may be also higher voltage, up to +/-2.5Vpk. For now ...
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2k views

How do I amplify the difference between two voltages?

Starting at the beginning: I have a shunt that carries DC current, and the voltage drop is very slight. I want to amplify it in order to see it better on oscilloscope, and to have it scaled correctly ...
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40 views

DC shunt motor electrical

A 5KW, 220V DC Shunt Motor draws 2A at rated voltage when running light. If the armature and field resistances are 1Ω and 165Ω respectively, determine its efficiency when running as a motor drawing an ...
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28 views

Measuring current output of a diode driver

I have a laser diode driver chip that can produce DC currents up to 200mA. The current is adjusted by a potentiometer on the driver chip. The driver chip has four pins: inputs: GND, SUPPLY outputs: ...
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48 views

Calculating uncertainty in a current divisor

I had the following exercise to do for college: I designed an analog ammeter exactly like this: simulate this circuit – Schematic created using CircuitLab The idea is to design an ammeter ...
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2answers
553 views

What is the purpose of clamping the gate and source of a mosfet

Is clamping the gate and source of a MOSFET really important? I have seen this in some articles and some datasheets of MOSFETs where they have built in clamping. As far as i know they are used for ...
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72 views

Why don't we need to consider \$R_4\$ and \$R_5\$ when why calculate \$I_1\$?

My book said that \$I_1=I_T \times \frac{R_1}{R_1+R_2}\$,and \$I_2=I_T \times \frac{R_4}{R_4+R_5}\$ simulate this circuit – Schematic created using CircuitLab I have two questions about these ...
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115 views

Why does the voltage across a shunt spike then settle?

I'm using a 50 Ohm shunt to measure a current of about 50mA driven by a voltage of 110v 60Hz AC as a zero-crossing square-wave (with a step at the zero-crossing). Using my oscilloscope I can see ...
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1answer
136 views

How can I accurately and precisely measure current in a 110V AC circuit, with a 1kohm-50kohm load, using an oscilloscope?

I need to measure the electrical resistance of a volume of ground. To do this I need to cause a current to flow between two metal electrodes pushed into the soil (let's call them the "current" ...
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2answers
124 views

LDO quality with current measurement shunt

I'm designing a power supply block and need to measure the current flowing trough a LDO. It is clear that the current in front of the LDO and after the LDO are the same (apart from some tiny bit used ...
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1answer
170 views

How to connect 50 A 12AWG cable to a shunt resistor in PCB?

I'm designing a PCB in which the current of a BLDC motor is measured through a PSG4NTEBL500F shunt resistor. The DC supply of the motor is connected to the PCB through a 12AWG cable and the circuit ...
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1answer
68 views

How to select shunt resistor value of the below circuit? We can use Ohm's law but I am still a bit confused

I am very new to hardware development. I am learning all the basics to design a battery management system for electric vehicles in the future. I would like to know how to select a shunt resistor for ...
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3answers
311 views

large voltage spike over shunt resistor even at no load

I'm trying to build a stepper-motor driver. Each windig is driven as shown: at the moment, im feeding this with PWNM signals of constant duty cycle, just to see how everything response. (PWMs are ...
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2answers
410 views

Wrong ground reference producing wrong output on ADS1115

I am currently working on a project, which involves measuring current in a DC circuit and storing that generated data on an arduino microcontroller. I decided to go with the ADS1115 and a shunt, which ...
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74 views

Understanding purpose of a resistor in reference schematic TIDU034

Gents, I'm analyzing this schematic, but do not understand couple of things. I would be grateful if someone could explain in detail these questions: 1) R6 - shunt? What's the purpose of it? Under ...

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