Questions tagged [current-sensing]
The current-sensing tag has no usage guidance.
180 questions
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Current sensing nA to mA
I need to sense the current of a target MCU through various periods of its on/sleep/off state and then need to send this data back to another interface MCU to read out the value. They will be both on ...
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9
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Is it feasible to measure voltage drop across 0-ohm jumper resistors to determine excessive current draw?
We design very low-power devices which in standby mode use about 8 µA of current. They are powered by 3 V lithium primary cells and are designed to last for many years.
Every now and then we see a ...
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8
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3
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How is this a current mirror?
This article is talking about floating an IC's GND to use it at a common mode voltage higher than it is rated for. It then says it level shifts the IC's current output to ground by using the Q1-Q2 ...
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7
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8
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What is negative current?
I understand that voltage is relative to ground, so that can be negative.
However, I'm currently looking at current-sensors (ACS712 current sensor) and in the performance characteristics table, it ...
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7
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1
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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 ...
6
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1
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525
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Is it wise to determine heating element temperature from resistivity?
Context
I'm making an electric furnace for melting metal, and aiming to make my own controller.
Everyone seems to just use thermocouples and a control loop, I thought perhaps I could just measure the ...
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5
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2
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960
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The benefit to make or use a surface mount 4-terminal current sensing resistor
I find some precision SMD resistors are 4-terminal, like vishay's CSM3637P. It's constructed as below:
It seems it only make a slot on each pad, then get two extra pad to do the voltage measurement.
...
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5
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Measuring average current consumption in hardware
I'm working on a very low power budget, battery powered project. This project is allowed to draw 15uA (average) at 3v. The microcontroller we're using draws 4-10mA when active, and 2-3uA when asleep....
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5
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1
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430
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Wide range current sensing at +5kVDC
I am working on a control and interface board for high voltage supplies, which requires some current measurement to be implemented. The general terms of the question are similar to this one. The ...
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4
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3
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451
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Sensing current down to tens of nA with INA828 or other OPA
I need to measure the current draw of DUT that can be an MCU in deep sleep, such as Attiny85, or a more power hungry MCU that is powered off by TPL5110. In this post, I proposed a circuit where an ...
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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 ...
- 1,699
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4
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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 ...
- 265
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1
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2k
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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 ...
- 401
3
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2
answers
977
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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?
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3
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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 ...
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2
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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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3
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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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2
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Transimpedance vs. Non-Inverting Amp for high sensitivity application
In simple analysis, these two circuits give the same result ... i.e. producing 1V output for a 10pA input. Is there any advantage of one over the other in practice?
I am measuring currents in the ...
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1
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Automatic ranging current sensing
I am trying to implement a current shunt sensing circuit. This should be automatic and currently i want it to measure uA to around 200mA, and Change to the mA range at around 200uA. This is to profile ...
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3
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1
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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 ...
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3
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2
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386
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High side current sensing for negative high voltage
I need to monitor the current for a negative high voltage supply.
I implemented the following circuit in a simulation program:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/1867
But ...
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7
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1k
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Can a 4 to 20 mA current loop be measured without using a resistor?
Background
There is an electrical system typically consisting of a 4 to 20 mA transmitter and receiver.
simulate this circuit – Schematic created using CircuitLab
So far, everything is working ...
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2
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3
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899
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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 ...
2
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3
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341
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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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2
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1
answer
211
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High-side driver current monitoring via microcontroller
I'm building an automotive power distribution module which makes use of the Infineon BTS50010 high-side driver.
The high-side driver current is monitored via the sense pin (IS) connected to a ...
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2
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1
answer
172
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How to sense a varying current and voltage without affecting the load
I've been asked to build a circuit to switch a constant power (varying current & voltage) supply between two loads, for a research experiment the customer is carrying out. The loads are unknown ...
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2
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1
answer
265
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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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2
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1
answer
2k
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Shunt resistors and PCB layout
I have several questions about the current sensing through a resistance.
The resistances are 2-SMD package and I will use the 4-wire kelvin method for the layout.(see image) Specifically, there are ...
- 526
2
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4
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703
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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 ...
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1
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Can I use the existing current-sense resistor of LTC1473 for my own measurement?
I'm making a powerpath battery switcher using LTC1473. For its own inrush/short management, the LTC1473 uses a shunt resistor connected to its sense+ and sense- pins.
Since I also need the current ...
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2
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1
answer
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Troubleshooting Voltage Sensing Issues in Buck-Boost Chip Simulations
I performed a simulation on a buck-boost chip (LT8390). I understand that the sensing resistor placed between LSP and LSN is supposed to sense the differential voltage. This voltage is then amplified ...
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2
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2
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867
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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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2
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1
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864
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High side, high voltage, micro ampere current sensing
I am working on a project in which I am required to sense current in micro ampere range from a 2 kV power supply. Here is a link of an article which I am referring.
https://www.analog.com/en/technical-...
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2
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2
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160
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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 ...
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2
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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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3
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High-side current sensing diagram
I have a load that can be connected or disconnected from a +5V source (let's assume there is a switch). My target is to trigger an output to high-level voltage if the load is connected, and trigger it ...
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2
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1
answer
215
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Understanding current sense circuit
I'm trying to adapt a current limiter design that I found, and I'm having trouble understanding the "current sense" part of it.
The current sensing is implemented using a shunt resistor, ...
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3
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395
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Designing Eddy Current Sensor?
I am looking to build a eddy current sensor, I am having difficulty finding information on how I should be designing the sensor to fit my needs. There's a few studies and articles I've found that ...
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2
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1
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542
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Current Transformer Current Sensing via operational-amplifier
This is a current sensing circuit, L1(CT2320) is a current transformer, U1 is generated by IGBT inverter ，U is one of a three phase of the motor driver voltage. I have several questions about this ...
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2
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1
answer
223
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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 ...
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2
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2
answers
399
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Current Sensing Amplifier Circuit explained
I've been trying to understand why each every comment is in the circuit shown. I understand that the amp is taking the voltage drop across the Rsense and amplifying it such that the current across it ...
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0
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Window current detection through a current sense differential amplifier and a comparator
I'd like to implement a circuit to detect the over-current through a grounded load. The limits for that current are either 3mA DC current or -3mA and 3mA in case of bipolar AC current. I want to ...
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2
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1
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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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2
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0
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206
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High voltage 1100 V current sense on the high side
I have the circuit that you see below.
My load is a photomultiplier tube equivalent to a 3.63Mohm resistor.
My power supply can deliver max 4W (2kV and 2mA). I use it on 1100V and the load draws ~...
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0
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379
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Problem simulating LMP8645 current sense amplfiier in LTspice
Basically the problem i am getting is that the output offset voltage is extremely large (58mv)
here is the datasheet for the amp: http://www.ti.com/lit/ds/symlink/lmp8645hv.pdf
on page 9 it shows ...
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1
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2
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97
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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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1
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4
answers
696
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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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1
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2
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889
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High-side current sensing with a rail-bound instrumentation amplifier?
I know that current shunt monitor ICs and high common-mode voltage differential amplifiers like the INA117 and AD629 exist but I'd like to know if it's possible to use a regular instrumentation ...
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2
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7k
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AC Current Sensing Switch Using Current Transformer
I'm struggling to design a circuit that will interpret signals from a SCT013 current transformer and trigger a constant 5v signal (which will go to a microcontroller) when a certain current threshold ...
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1
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1
answer
439
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What are shunts, as related to their use in current sensing in microcontrollers?
Within the manual for the I/O module I'm using (a Loytec LIOB-153) there are wiring diagrams to aid in wiring up your sensors and other inputs/outputs. There are two wiring diagrams for the purpose of ...
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