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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Current shunt not working

I was using a 12 ohm current sensing resistor and I was getting 26mVAC across IN and IP. When I switched to a 100mohm resistor then I was getting around 8.2mVAC across IN and IP Load = 300W and ...
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2 answers
96 views

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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Feedback impact of collector-base shunt resistor in common emitter amp stage

I made this 3 transistor Rf amp which works well at 10 MHz and has 50 ohm output impedance, a gain of 8.2 (18.3 dB) and quiescent curent of 28.6 mA. It consists of a common emitter stage followed by 2 ...
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CSA - Pulses on the output of the low side current measurement amplifier

I'm a bit lost at the moment, since I see pulses on the output of my CSA and I cannot really see, why this happens. The pulses occur immediately, when I apply a PWM signal to the gate driver (...
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Current Shunt Amplifier Problem (MAX49921)

I'm currently trying out the evaluation kit for the MAX49921 from Maxim, and I'm having a few problems with it. First thing to note is that my board appears to be an issue a board, but all the ...
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5 answers
142 views

Can I use a normal diode as a Zener/Varistor ? If not, why not? (focus on Varistor use)

When I look at a normal diode graph like that I see the Vz Zener voltage of it looks just like a Zener, so why not using it reverse biased like a Zener? I ask like that because I never saw it being ...
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Current measurements - shunt switching

I have been designing a current measuring device, and since it requires high wide-range accuracy, I decided to use two shunt resistors of different sizes. The schematic is shown below: The design ...
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41 views

Shunt both op-amp input terminals individually

I'm working on a lab project for my class. My manual says that I need to shunt both OPAMP input terminals individually with resistors Rx = 1kΩ. I'm not sure what that means. Where should I put the ...
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Shunt voltage direction circuit [closed]

I need to know which terminal of a shunt is higher, ie whether I'm charging or discharging my 12v battery bank. The voltage difference is very small (max 74mv) since the current flowing may be tiny, ...
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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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2 votes
3 answers
185 views

How to parallel shunt resistors with 4-terminals (Kelvin connection)?

I would like to use multiple shunt resistors in parallel to reduce power dissiption to the power specified per resistor. However these resistors are 4-terminal resistors WSL40265L000FEB. The reason ...
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SMD "power" resistors : what constraints on PCB layout

I'm looking for current sens resistors. As those are rather big (and beeing for now the limiting element for my PCB size), I would like to stop using over-rated one and take some with "just" ...
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15 votes
4 answers
1k views

Why would a current measurement shunt design use 4 sense pins?

I am interested in low resistance shunts (tens / hundreds of microohms range) used in high voltage / high current setting. Typically, those are busbar-mounted shunt resistors like this one: The ...
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0 votes
2 answers
89 views

Do battery shunts (e.g. 500A/50mV) lower the final voltage on the system side by 0.05V / 50mA?

So I have this shunt in my power system connected just a few inches from the battery bank's final outgoing (to system) negative terminal. But I can't seem to find any data on whether or not these ...
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High Side, High Voltage Shunt Measurement with Differential ADC

I need to measure the high-side current out of an LED driver. The problem is that the output voltage can be as high as 250V. One solution would be to float an ADC and digital isolator just below ...
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3 answers
188 views

Why is it important to eliminate ground-shift at the ground of a microcontroller?

I've asked a question about differential amplifiers and their uses in measuring current through a shunt. In doing so, lots of people advised me not to sense current on the low-side since that can ...
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6 answers
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Do you have to use an instrumentation amplifier to measure voltage across a 0.01 ohm shunt?

I was planning on implementing a current sense feature on the STM32 Bluepill to measure the current output of a solar panel (150 mA short-circuit current, 14 V Open-circuit voltage) using LM358 ...
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4 votes
2 answers
709 views

Where does one find the minimum voltage above the negative rail an op-amp can output in their datasheets?

I was planning on using a UA741CP (from TI) as a differential amplifier (to get a current value from a shunt resistor and then administer that value to the ADC of an MCU to avoid noise). However, I ...
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2 votes
0 answers
86 views

Shunt current measurement on phase

I measure the current of two phases (directly phase current, not the low side MOSFET current) of a PMSM motor and on some hardwares (2 of 10) I have issues with the phase current measurements. As a ...
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2 answers
154 views

How to calculate the pulsating current flowing through a shunt resistor?

If the current flowing through the shunt (0.5 ohm) is in pulsating form (PWM with 50% duty cycle and 100 Hz frequency,) how do I calculate power loss through shunt in order to choose proper for ...
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3 votes
2 answers
924 views

-25mV output from op-amp with 0V input

I have this simple op-amp circuit used to amplify the voltage drop across an unknown resistor with a value between ~0 and ~20 ohms. The circuit works close to expected, but there is an offset - when I ...
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1 answer
138 views

Why does the value of shunt resistor need to be very high for solar cell's greater efficiency?

In the circuit equivalent of a solar cell, shunt resistor is described as "The irregular polycrystalline lattice grain boundaries that resist to the flow of electrical current in the silicon ...
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64 views

Why do I keep blowing this current shunt amplifier?

I'm using an INA293B3-Q1 current shunt amplifier in the standard high-side configuration as shown below. The supply is a variable DC power supply (0-20V). Rsense = 1 mOhm. And, the load is a ...
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High current thermal bypass

I am using a shunt to measure the current on a 12V system on a boat. Most currents are very low (under 4 A) but when using the starter the peak current reach peaks of 250 A. I've sized the shunt to 50 ...
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95 views

Current sense resistor - Should I consider self-heating contribution?

I am trying to implement a precision current sense amplifier. I am calculating now the tolerances introduced by the resistor. I know the maximum drop will be 20mV and I will use a 5mΩ resistor. Max ...
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4 votes
2 answers
2k views

Resistor in shunt regulator not following Ohm's law?

I was reverse engineering a power tool battery charger (21V SMPS) that derives its 5V rail from a simple shunt regulator, employing a TL431 programmable precision reference and a NPN transistor, as ...
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2 answers
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creating a differential amplifier for low voltages (current shunt)

I'm trying to create a "precision" fully differential amplification stage, to measure uA on a 10R shunt, and mA on a 0.01R shunt. shunt resistance values are set at those values for burden ...
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1 answer
165 views

Shunt resistor after MOSFET and op amp to amplify voltage

I'm trying to figurate out how to measure current in circuit. I have idea to use shunt resistor but after connecting op amp on shunt I have some unpredicted measurements on output of op amp. I want to ...
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0 votes
1 answer
123 views

Best practice for paralleled four leg shunt resistors connection to a shunt amp, and best placement

I am using three WSK12161L000FEB paralleled together on a four layer PCB for a three phase motor controller (9 shunts total in design, 3 for each phase) From my understanding, a kelvin connection to ...
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1 vote
1 answer
146 views

Limiting current with a shunt resistor

For my project, I am using a 3.3V source to run two motors. If the motors pull more than 1A, then they have to stop. I was told to do this with software and hardware protection. As a programmer, I ...
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58 views

Fixed voltage drop (current and temperature independent)

simulate this circuit – Schematic created using CircuitLab Is there a clever way to create a fixed voltage drop say 2V that is not affected by current or temperature? Voltage stability should ...
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2 answers
176 views

Voltage stability factor of voltage regulation circuits

Here a shunt voltage regulator circuit with two Zener diodes. One Zener diode Z gives the reference voltage at the comparator given by T1 for the feedback signal out Ra-Rb potentiometer. I can't ...
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1 vote
1 answer
323 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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0 votes
1 answer
92 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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0 votes
0 answers
52 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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0 votes
1 answer
285 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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1 vote
2 answers
117 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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1 answer
95 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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1 answer
136 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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1 vote
0 answers
56 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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1 vote
2 answers
498 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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1 vote
1 answer
81 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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0 votes
1 answer
126 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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1 vote
0 answers
274 views

DC current continues measure using shunt resistor with ADS1115 and ESP8266

...
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0 answers
175 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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2 votes
0 answers
108 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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1 vote
2 answers
102 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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1 answer
76 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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0 votes
1 answer
54 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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1 vote
1 answer
137 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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