Questions tagged [current-sensing]
The current-sensing tag has no usage guidance.
180 questions
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Is amplification needed for high-side current sensing?
I have a 5 V system and I want to monitor the current in different parts of the system. I am planning to place a small value resistor on the positive power rail and feed the rail voltage and the ...
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Current detector transformer on optocoupler
I need a current detector that outputs a logic signal (1 or 0). I DON'T need to measure current.
Detected current: AC.
Voltage: 220V.
Load power: ~1kW.
FOR EXAMPLE: I need a current detector that ...
- 25.5k
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How to sense if a heater is plugged and on
I want to remotely check if one of my home sockets (which happens to power a heater) is transmitting current or not. I do this as a hobby project, so my main priority is to learn through the process ...
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Removing the effects of Parasitic Inductance in current sense resistor – Low side current sensing
We are evaluating MIC21LV32 from microchip in one of our applications.
For the current sensing we have used 3 mΩ sense resistor (1206, 1 %, 1 W), as these sense resistors have higher ESL+ parasitic ...
- 16.8k
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LEM current transducer 2.5 V internal reference
I am testing a LEM LTSR-25-NP current transducer. According to the datasheet, the current transducer should be outputting 2.5 V +/- 0.025 V when the input current is 0 A, but this is not what I am ...
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AC Current Sensing LED indicator circuit
I'm playing around with a circuit to drive a LED based on the output from a current sensing transformer. The idea is to have the LED appear proportionally brighter with the output from the current ...
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How can we say this current sensor doesn't measure DC?
Digikey is saying this current sensor "CS0305B" from CUI Devices can measure AC and not DC.
But in datasheet there is no reference or note mentioning this current sensor will not measure DC.
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Best approach for using multiple power monitors with single MCU (SPI)
I'm working on a project where I'm using several buck converters controlled by the same MCU (ESP32) and I will be adding a digital Power monitor to each converter. but I'm concerned about the number ...
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Current sensing resistor placement [closed]
I will be adding a current sensing resistor to a Buck-boost DC-DC converter. Based on the IC datasheet, the resistor is placed at the low-voltage side next to the power inductor.
But, as far as I know,...
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Current Sensing Trace Routing
I'm developing a motor control board (sensorless FOC). I have a question about the differential pair traces, they are very long (the longest is about 80 mm) and crosses several gate lines. How bad is ...
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Current sensor for sensing 6 mA DC & 30 mA AC current [closed]
I want to sense very low currents for both AC & DC for an EV charger application. General AC & DC sensors do not have that much range to sense the current. Please suggest some good component ...
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What does sensitivity mean for a current sensor when given in "mV/N" or "mV/mT" rather than "mV/A"?
I have been analyzing various datasheets of current sensors and majorly getting sensitivity given in "mV/A," from which I understand the output voltage per 1 ampere. I do not understand it ...
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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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Self powered current sense in tapped inductor buck converter
I am interested in designing the autonomous (both turn on and off) high-side high-voltage switch proposed in this paper. The proposed topology of the high-side switch is as follow:
Auto-turning on is ...
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How to sense the current an amplifier is supplying?
Consider the circuit below. It is made up of three parts: input, bidirectional amplifier, and output. If we set the gain of the amplifier to 1, then it as if we've just connected the input to the ...
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Choosing the kind of current sensing method and the voltage of the testing signal for a DIY LCR meter
I have been designing my own LCR meter that uses the V-I method to make measurements. I have finished the sine wave generator and processor side, but I got stuck at the sensing part.
Here I have 3 ...
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Unexpected behaviour of current sensing circuit with op-amp
I would like to use the schematic below to measure the output current of a buck converter (0-10 A) and convert it to a voltage of 0-3.3 V which is read by a microcontroller. During startup I sometimes ...
- 47k
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Can a non-invasive AC current sensor measure DC current? [closed]
Can a non-invasive AC current sensor measure DC current? What is the theory behind it?
- 16.5k
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Closed-loop Hall-effect sensor operation
I know that closed-loop Hall-effect sensors generate a current in the secondary winding to oppose the flux in the core such that the net flux will equal zero.
At this point the current in the primary ...
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143
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Help understanding conflicting results from INA190 current sense amp
Built a board for a drone that has a few things onboard, though the one that is messing me up is the current sense chip, INA190, though it's most likely not the problem.
Picture 1 show the big yellow ...
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3-phase inverter low side current sense
The setup
I'm currently doing some experimentation with 3-phase inverters for BLDC motors and current sense. I have at hand this board featuring:
IR2103 MOSFET driver. LIN# inputs are connected to ...
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How to select current sense resistors for ir2136 ITRIP signal
Looking at the datasheet of the IR2136 it suggests this little resistor network as input for the ITRIP pin.
https://www.infineon.com/dgdl/Infineon-IR213-DS-v01_00-EN.pdf?fileId=...
- 473k
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op-amp level shifter
I'm working on a brushed dc motor driver and I have to monitor the current. so I use ACHS-7121 current sensor. This sensor convert +-10A into 0V to +5V and have +2.5V in zero current.
Now I want to ...
CommunityBot
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Some questions regarding measuring current using ACS712
I'm using an ACS712 0-5A current sensor to measure the input current to a boost converter for the implementation of MPPT algorithm. To do so, I need to connect the ACS712 chip in series with a PV ...
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How critical is the sense resistor?
In the following topology, two 0.68 ohm resistors are paralleled to result in 0.34 ohm for sensing the source current. Can I use three paralleled 1 ohm resistors to result in 0.333 ohm? Does this ...
- 38.5k
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Most accurate way to measure universal (AC) motor current?
I'm designing a control circuit for a universal (AC) motor (single phase, brushed).
I've simulated the control circuit and it works as expected.
Circuit below is controlled by a STM32G4 series ...
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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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Designing a high-side current sensor
I'm trying to design a high-side current sensor for limiting the current in a circuit I'm building however I'm very inexperienced with the operation of high-side current sensors.
This is my circuit:
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Unexpected output with INA138 current sensor
I have no experience with current sensing ICs and I'm trying to build a current sensor with an INA138 IC that I've imported into LTspice. From the manufacturer's website, I'm expecting my output to ...
- 73.5k
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Sensing current into a battery while charging
I want to sense the current into a 84 V battery while charging and disconnect it when fully charged using a MOSFET. Is it advisable to use lowside current sensing? I used a noninverting opamp ...
- 16.8k
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AC current detection with 1-10mA sensitivity
I need to build a current switch that will be connected to an Arduino (or Raspberry Pi) digital input. I need it to set to HIGH (3.3 V) if the current is above some threshold, and LOW otherwise. The ...
Null♦
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Voltage divider dropping voltage more than expected
I'm trying to connect an ACS712 current sensor to an ESP32 ADC pin. The ESP32 expects 3.3 V, but the ACS712 can reach 4.5 V.
When there's no current going through the ACS712, its signal is 2.5 V, so I ...
- 172k
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Why do I have a sudden current peak when PWMing a valve?
I am driving a proportional solenoid valve with PWM from an MCU as follows:
The voltage of the MCU is 3.3 V. The gain of the amplifier is set to 20 V/V. Because the valve consumes 170 mA when fully ...
- 16.8k
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Current sense pin detect too quickly (Flyback)
Here is my circuit:
simulate this circuit – Schematic created using CircuitLab
There is two problems:
Firstly, the sense circuit don't open the mosfet at 1V, yet the zener at the V+ in the amp ...
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Current Sense Amplifier / Differential Amplifier Negative Voltage On GND pin OK?
Right now I'm picking a current sense amplifier for my application, and I'm looking for for amplifiers with maximum offset voltage of below 50uV (and offset and bias currents in nA/pA range).
Luckily, ...
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Isolated Current Shunt Amplifier
I have twenty isolated power supplies (around 40 V max) which need to have their current draw sensed and monitored. I'm currently using a TI INA138 current sense amplifier, which sort of works.
...
- 23.8k
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Current Sensing with Op-Amp, do I need a shunt resistor in series with the load on the output?
Hi I am building a circuit to measure current draw from a load, I opted for a voltage follower with a transistor and a shunt in between, The transistor is needed to allow higher currents to flow ...
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MAX9919 Thermal Pad
I am designing the thermal outline plane of this current amplifier ic in a 4 layer board using Eagle Pro. This board will be made using ENIG process.
After spent so much time trying to understand in ...
- 148k
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Measuring PWM controlled current with a microcontroller
I want to measure current using sensor MLX91220 which gives output in analog.
I have battery that I charge and discharge via switching MOSFET and want to measure current on this grid.
Problem is that ...
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Op amp with transistor in feedback
I am currently looking for a high side current sense IC. I have noticed that most of them that are without galvanic separation, are using an op amp with bjt transistor like in bellow schematics:
The ...
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Sensing voltage drop across the load in the H bridge
I use two BTN7970 to make a full bridge circuit. The load is a piece of shape memory alloy(SMA) wire.
I want to accurately measure the net voltage drop on the load excluding caused by mosfet's RDS. ...
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Why should the fullwave current sensor bandwith be about 10 times switching frequency?
This is an example of high side switch current sensor in a buck-boost converter.
I read that for high-side switch full waveform sensing the current sensor bandwith should be about 10 times switching ...
CommunityBot
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Bipolar high-dynamic range current sensing
I'm working on a project that will necessitate bipolar current measurement across a wide current range. It will need to accurately measure current from 750 mA down to 1 nA, although greater. The ...
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Power outage detection to kickstart a safe shutdown and data retention process
I plan a system that operates on a 5v rail.
The power is supplied from an outside DC source.
The 5 V powers an RPI CM4 and other components that are controlled by it.
The whole system requires up to 5 ...
- 16.8k
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How do you analyze this simple circuit? [closed]
I want to plot Vout vs time graph (which software do you suggest) and also want to find out max and min output voltage (Vout) of the circuit. How can I find the max and min manually?
Can I find them ...
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non-inverting current sense op amp output unstable during the measurement
I would like some advice on how to solve the following problem. The following circuit is motor driver with current sense circuit. The circuit run motor at cca 30mV when is not under load, but when the ...
- 11.8k
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How to measure very low current by amplifying it?
I am trying to measure current from a DC circuit. So it basically I am trying to make an ammeter. I am using ACS712 20A current sensor and Arduino UNO. Theoretically, I can measure a minimum of 50 mA ...
- 73.5k
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Can a floating capacitor terminal be used to collect electrons?
I want to collect charge from an electron beam source. For that, I'm proposing to put a floating capacitor with its bottom terminal floating and directly exposed to the electron beam gun. The top ...
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Sensing Ground Faults on a High Voltage Pulser - Coupled Inductor Issue in LTSpice
I am building a ground-fault protected High Voltage Pulser. The pulses may be as high as 500V and as narrow as 50us (20kHz).
The question of how to create GFCI protection is proving to be a ...
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Noise problems in current sensing
I have the following circuit:
simulate this circuit – Schematic created using CircuitLab
I am using a motor from an electric bike, as a generator and I am rotating it using a drill, to test ...
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