Questions tagged [current-sensing]

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4answers
169 views

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 ...
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2answers
68 views

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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2answers
55 views

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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1answer
64 views

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. ...
0
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1answer
24 views

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 ...
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2answers
66 views

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 ...
1
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4answers
139 views

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. ...
-1
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2answers
79 views

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 ...
0
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1answer
63 views

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 ...
0
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1answer
43 views

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 ...
0
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1answer
82 views

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 ...
0
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2answers
67 views

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 ...
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0answers
21 views

Multiple statuses displayed in LEDs and piezo [sometimes]

Essentially [and this may sound a little overkill] I'd like to run current sensors from three sources to indicate whether electric or EM locks are engaged and to feed off of reed sensors to feed the ...
0
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2answers
93 views

Current sensing relay that momentarily closes contact each time state changes

I have a 240V dust collector that I manually switch on and off using a one-button wireless remote. The dust collector is connected to several machines. I'd like to use a current sensing relay to ...
0
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2answers
447 views

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 ...
7
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1answer
569 views

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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0answers
29 views

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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0answers
50 views

CMRR error calculation

I need to calculate CMRR error for the current sense circuit. From Texas Instruments I have the following formula to calculate the CMRR error: Schematic of my device looks like this: There are two ...
0
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1answer
63 views

Switched Mono jack + battery: Make circuit when plugged in

I would like to replicate the functionality inside the Ampoids guitar amp (9v battery) in which the circuit is turned on only when you plugin a male 6.3mm mono jack to it I believe that the most ...
1
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1answer
38 views

Dedicated current sense amplifier vs simp,e difference amplifier

I need to implement low-side current sensing for a H-bridge motor driver. While there are dedicated current sense amplifiers such as TI’s INA180, can I use a simple difference amplifier for this with ...
1
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2answers
58 views

Why most non-invasive current sensors have a minijack at the other end?

If I search on google for non-invasive current sensor and click on the images tab, in most cases, I see a minijack at the other side of the wire. What is the reason for this? Is this minijack supposed ...
0
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1answer
141 views

Compact Voltage-Controlled Current Source Array

I'll start by asking what it seems to me a trivial but I don't know what is the most efficient solution. Electronics is not my main occupation, so I may need some indication to proceed: I need to ...
0
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1answer
96 views

Adjustable CC/CV supply with voltage and current limiting having no output voltage at low voltage levels?

Im trying to create a power supply with an addjustable output between 0-12V or 0-3A (CV and CC adjustable). To make sure that the components don’t get damaged I'm trying to implement a protection for ...
0
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1answer
38 views

How to share a current sense pin on a single GPIO

The BTS7040 is a 2 channel High Side Switch with diagnostic feature, im planning on using 2 of the IC and i dont have extra GPIOs to spare. The way you read a fault from the BTS7040 is to select a ...
0
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1answer
51 views

Detect power outage and disconnect heavy loads from the UPS [closed]

I am looking for a simple system to detect power outage and disconnect heavy loads from the UPS backup to maximize the longevity of the power backup. The UPS works on a 24-V battery. The UPS switch ...
0
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1answer
603 views

INA219 current sensor not working properly with DC motor

I use INA219 module to read DC motor current for control propose. I connect INA219 in series with motor as shown in schematic. simulate this circuit – Schematic created using CircuitLab The ...
0
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1answer
89 views

Current Sense circuit with digitally programmable gain

I'm designing a precision source meter and I wanted to put a couple ideas out to the community. One thing I will note is that this device has 32 channels, so I need to be very cognizant about both ...
0
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0answers
112 views

How to average output of current sensor to get smooth output?

I am using INA138 current sensor with 100Hz, PWM duty 5%, 8-bit resolution signal load is a resistor, I getting zero readings while actual current readings also appear, edited - zero current sense ...
0
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0answers
34 views

Designing high bandwidth current sensors for inductor current sensing

I am designing a high-frequency current sensor, suitable for sensing +/- 20 Amps at frequencies of 200kHz. This is being used in average current mode control application in an isolated forward ...
2
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1answer
118 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 ...
0
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1answer
268 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 ...
0
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2answers
221 views

Converting a 4-20mA 24V signal to 0-5V?

How do I convert a 4-20mA 24V signal to a 0-5V signal, suitable for A-D conversion with a 5V microprocessor? Can this be done while isolating the 24V from the 5V output?
1
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0answers
55 views

Detect Battery Insertion in USB Charging Circuit

I'm using an MCP73831T as the charger IC, I've figured out how to detect the charging/charged, this was easy, however, I would like to know when the battery is actually plugged in, I know when the usb ...
1
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1answer
214 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 ...
0
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1answer
38 views

How to sense current AC of a sinusoide -100mA to 100mA with 70kHz

Any suggestions about a chip or PCB component that could work? I tried to use the the current sense transformer PA1005.050NLT https://www.digikey.com/product-detail/en/pulse-electronics-power/PA1005....
0
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1answer
129 views

Current Sense Amplifier Potentials

I'm trying to implement a current sense amplifier in my application, but I have a question about setting it up with regards to current flow. Basically, in this case, you put a very small shunt ...
0
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3answers
435 views

Current Sensing on positive and negative voltage rails

I'm working on a design that uses two separate buck regulators to generate a positive and negative voltage, and I'm trying to implement current limiting with a current sensor. However, I am running ...
0
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2answers
84 views

I am looking for a 40 input OR gate which minimize PCB space

I am using 40x ICs INA301 to measure overcurrent in 40 interfaces Finally I want to have 1 single "output" to signal if there is an overcurrent in ANY of the 40 interfaces I don't want to utilize any ...
4
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4answers
123 views

Charge indicator with comparator - very sensitive to noise

I need an indicator when the current from my charger is larger than 100mA. I tried the below circuit but this seems very sensitivity to noise. Probably I am getting some ripple in the mV range from ...
1
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1answer
174 views

Reading registers from ACS71020 over SPI

I'm trying to read registers from current-sensing chip ACS71020 connected over SPI. This is how I initialize the SPI: ...
1
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2answers
87 views

AC phase current sensing using Isolated delta-sigma modulator

I am trying to design a isolated AC current sensor. I've chosen the AMC1106 Isolated Delta-Sigma Modulator. (change my mind if you think there is a better solution for 220V AC; 2A Max; 0.25%) The ...
1
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1answer
75 views

Load sensing relay/power switch/adapter which switches on when it detects some load on its input

Complete newbie here. I'm not using the right terms, so my apologies in advance. The problem is simple. I want my powered computer speakers (2.1) to turn off when the computer is turned off. I have ...
0
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1answer
43 views

Method for sensing fault currents with microcontroller

How do I choose a proper approach for detecting ground fault currents (20 mA through 30A, 60Hz)? Let's say I have a zero sequence CT and calculate a burden resistor. I have a 12-bit ADC in the micro. ...
2
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1answer
102 views

Measuring AC Current at High Voltages (up to 600VAC)

I've been looking at various ways to measure current for a while now, and am stumped on how to read high-side AC Current Measurements ohmically (no Hall Effect sensors). My initial thought was to use ...
0
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1answer
129 views

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 ...
2
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2answers
361 views

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 ...
0
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1answer
400 views

Current sensing relay with delay on break for dust collection system

I am in the process of planning our a new workshop in a single car garage. I have a large 20A Dust Collector that needs to be on its own circuit or else it will trip. I also have a ceiling mounted ...
2
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3answers
759 views

Detecting switch closure

Any techniques/circuits/sensors that can determine the open/closed state of a set of contacts, independently of whatever power or signals are being switched by the contacts? Obviously easy if there's ...
0
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1answer
67 views

Output current and voltage levels regulation in ac/dc adapter

On the picture below is the output circuit of AC/DC adapter. I understand how voltage level contol works, but I don't understand how exactly current limitation works and how should I calculate ...
1
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1answer
444 views

High voltage and cheap differential amplifier

Can I use a LM324N (very common) op-amp to act as a high-side differential current sense op amp at high voltage? The Differential Amplifier The differential input voltage rating is 32v, but my load ...