Questions tagged [current-measurement]
Measurements of the current flowing through a circuit
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Heat element /coil voltage calculation [closed]
I have been wondering,
How do you calculate the highest voltage and current needed to power a coil or heat element?
Is it by the resistance + lenght + size?
I need to know the best way to calculate ...
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2
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What is the current through the resistor?
In the figure we are supposed to find the current in 8ohm resistor. So by using simple KVL rule I was able to figure it out to be -1.25A.
But in the second approach
When I calculated current in 8 ohm ...
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Measure power & energy usage in tapped line
Here is the schematic of the circuit in question:
The horizontal lines are from the AC mains. Ammeters and wattmeters are connected at any 2 points in the main lines. I am trying to detect if the ...
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Would a Hall effect sensor be damaged by gross saturation?
There's this old question that is almost what I'm looking for, but not quite.
I want to make a current direction sensor - I don't care about magnitude - for a car starter battery. I care about the ...
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Low side BLDC motor phase current measurement
I'm trying to design a current sense circuit for measuring a phase current in a BLDC motor. Here I'm using the embedded opamp in the STM32G4 MCU. What voltage will be at the output of the opamp here ? ...
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Monitoring ground mA current via voltage transformer [closed]
The TL;DR
Can a voltage transformer act as a milliamp current sensor? They resemble in structure.
Explanation
I want to build an approximate ground leak milli-ammeter (0.1-30 mA) for some appliance.
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PNP BJT current mirror across shunt resistor used as current meter
Usually, to measure current in the line the next sch can be used:
simulate this circuit – Schematic created using CircuitLab
Here Vref is proportional to current through Rshunt as
$$
V_{ref} = ...
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Signal conditioning for a current transducer
I am using a current transducer (LPSR 15-NP) to measure the current that is flowing through my AC servo motor powered by my SVPWM PCB. I have currently implemented an open loop control to the motor ...
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Designing a self-power current range detector
I need to design a current range detector i.e. a module with an AC current as input and a digital output. When the current is within range (i.e. between 0.1A AC to 2.5A AC), the output should be a ...
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ESP32 simulate a current transformer
I currently have a current transformer that generate a 0 to 0.7 V AC voltage (in my case) when reading. It is actually an SCT013A current transformer.
I would need to simulate it using ESP32, so ...
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Lower current than specified with LEDs' calculations for power supply
I have 1 meter of this ledstripe with 144 LEDs per meter. It is specified:
144 diodes/m = 34.56 W/m
That would make 6.912 A per meter. But when I connect them and ...
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What limits amplification of transimpedance amplifier?
I'm designing a transimpedance amplifier but I'm having trouble getting higher gain. I started with Rf being 16.5 kOhms but then I realized I will need higher gain, so I simply switched it out for 50 ...
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Hall effect current sensor offset removal using opamp
My hall effect sensor (WCS1700) outputs 2.5v at zero current, I need to remove this offset voltage, and also amplify output.
I utilized both the opamps of LM358, first stage (A) to amplify signal and ...
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Is the "two-wattmeter" method enough to measure active power into a BLDC motor?
I have a 4-channel scope, 2 current clamps (to measure \$i_2\$ and \$i_3\$) as well as 2 voltage probes (to measure line voltages \$v_2-v_1\$ and \$v_3-v_1\$ according to the aforementioned formula). ...
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Calibrating a high current shunt resistor
In a circuit I'm developing I have a shunt that is used for current measurement of +/- 80A. How can its calibration be done? Suppose our budget for this can be 1000 to 1500 USD, what would be the best ...
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How to properly measure the power being delivered to a BLDC?
There's a battery connected to an ESC, connected to the Motor, coupled to a Dyno.
How can I measure the electrical power going into the BLDC?
As far as I'm concerned a simple measurement of line ...
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Connecting current sense transformer directly to MCU/ADC vs using an OpAmp
I am currently designing a circuit where a current sense transformer is used to measure the current in a flyback transformer. The current sense transformer is connected in series with the flyback ...
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How to interpret input common-mode voltage vs output voltage in INA823 Datasheet
First, a similar question was asked before Understanding common mode vs output voltage graph for instrumentation amps, however, I failed to understand it with regards to my use case and need more ...
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ZXCT1082E5TA current detection circuit
I am trying to create a USB inrush detection circuit using ZXCT1082E5TA shunt current sensor. I want to control a 3.3 V signal, when new USB device is inserted. I did some research about inrush ...
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Differences between "Dark Current", "Sleep Current" and "Quiescent Current" in automotive related products
I am from automotive electronics tier 1 manufacturing company which makes Automobile locks and Remote keys.
In our remote keys, our team uses the term "Dark Current" for the default current ...
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How to quickly detect and switch off a shorted circuit (e.g. 30 VDC, 20 A intended, <5 ms response)
Summary
I'm designing a circuit that's meant to provide a short pulse of medium-low voltage, high-current, power from a capacitor bank to a low-resistance load, and I want to interrupt it if the ...
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Why is there a high minimum current required for a clamp meter to measure frequency in addition to current?
Modern clamp meters use hall effect sensors to measure AC and DC current and normally calculate True-RMS. But for the meter to display the frequency of the measured current some require significant ...
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Estimate DC current from phase current in BLDC motor
I am using a BLDC motor with sinusoidal windings that I drive with FOC. The implementation uses a triple half-bridge and a DRV83 to drive the MOSFETs. I have 3 low-side amplifiers to measure the phase ...
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How to measure the electrical properties to ensure the performance of a thin electrode/insulator stack-up?
I am a mechanical engineer by trade, and I am looking at some basic electrical properties that I need to measure to ensure the device meets the desired performance.
The device consists of a two-layer ...
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2
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Trans Impedance Amplifier with a photodiode
I made a Trans Impedance Amplifier circuit using a OPA322 op amp with a photodiode (Hamamatsu－S2386). I use a MCP3421 to convert the analogy signal to I2C digital signal after, and use a MCU to read ...
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Current transformer & power calculation questions
I have 3 x AT 50 B10 current transformers (CT), one on each phase (240V RMS), Vp, going into a CNC machine.
The output of each is 0-10V where each volt corresponds to 5A RMS passing through the CT.
I ...
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Shunt + hall: any advantages from combining those two?
Are there any devices that combine shunt resistor and Hall effect to measure the current with better precision?
Or, do I understand correctly that shunt is better in all aspects except of the heat ...
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Interfacing current transformer to DSP
I need to measure an AC current that of a flyback circuit with a peak of about 40A-50A at a frequency of 50 kHz on a 3.3V DSP. I figured out that the best way to do it is probably a current ...
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How to calculate the voltage and / or current in a crystal radio?
I have thought of using V=E*d for the voltage across the antenna (d being its length and E the electric field strength of the incoming radio wave) and then use I=V/Z with Z being the total impedance ...
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Common Mode Voltage on Current Sense Amplifier (direction of current)
From reading some threads here I understand that the Common Mode Voltage of a Current Sensor Amplifier when measuring high-side is the average of the positive and negative input pin.
In my application ...
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Can you use a charging IC to monitor charge and discharge current (or just charge?)
For my project I would like to incorporate coulomb counting/current measuring so I can calculate the SoC and capacity of batteries. However, I am not sure if you can monitor the charge and discharge ...
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Are there MPPT solar chargers that can also do coulomb counting/current measuring or is that a separate function? (for NiMH)
Are there any MPPT solar chargers that can also do coulomb counting, or do you need a separate fuel gauge IC for that? I have been looking for a while and there is no proof that an IC even exists that ...
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When an electromagnetic relay is switched on, it shows a dip in the coil current for a millisecond but then increases again. why?
I am currently studying the effects of current on the coil of an electromagnetic relay and came across this graph:
Image source: Ramirez-Laboreo, E., Sagues, C., & Llorente, S. (2015). A new ...
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Virtual ground not close to ground in a current to voltage converter
I was hoping to get some feedback on a circuit I'm building. The schematic is as follows:
Some description: This circuit essentially functions as a constant AC voltage source with current booster ...
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Current drop with capacitor
I'm new to electronics, and there's something I can't figure out.
Can someone explain to me why, when I add C1, the current drops drastically in R3?
I was thinking that the impedance will be the same ...
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Is it safe to connect buck feedback after current sense shunt resistor?
Is it safe to connect feedback voltage divider to output voltage after current sense amplifier instead of connecting it before current sense resistor? Will this connection influence regulator ...
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Common mode voltage suppression for low side high bandwidth current sensing
I want to measure current of short duration high amplitude pulses using a low side shunt resistor. The test pulses are up to 400ns (2.5Mhz) with amplitude up to 3000V, depicted in the picture below.
...
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Shunt's thermal EMF (Seebeck effect) vs Kelvin connection?
While reading this Vishay document about shunts, I saw that temperature mismatch between the shunt's terminals can introduce a "parasitic" voltage drop which will in turn affects the current ...
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How to convert voltage reading to current when using the INAx180 IC?
I am using a INA4180-4181EVM to find a suitable solution for measuring 0-2A of current in a DC circuit. In the datasheet, there is no equation given for calculating the current based on the read ...
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How to reset a current transformer core
I use a current transformer for pulsed current measurement (with DC offset).
It seems to me the core stores some energy after pulse disappear.
The transformer works at about 30khz a it has 2 turns on ...
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I2C Current monitor for low current (0-2A) application
I want to monitor current draw from a solenoid and also the total current draw of my PCB. The solenoid specifications are 24V, 11W, which results in a current draw of 0.458A.
I have considered hall ...
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Current Transformer Connections - Resistors and Capacitors
I was just going through the purpose of the current transformer and its working & using.
I found some schematics where I found a common pattern as below. It is a single-phase connection.
Line and ...
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Unexpected behavior of simulated differential amplifier
I need to measure a current from 1uA to 1A with a CM voltage up to 18v. I decide to go with a differential amplifier as per the following figure:
The expected Gain should be 50 V/V (=R5/R4) but at ...
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What is more precise: using an op-amp or internal PGA of an ADC to amplify a low-voltage signal?
I'm wanting to current sense a 10A load with high precision. I'm planning to use a current shunt resistor and then amplify/filter this signal before sending it to an ADC. Which design flow is ...
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Calculating spindle current if measuring 3 phase line current
I currently have a spindle that is being powered by a 3 phase supply. I am measuring the line current in each of the 3 cables using 3 current transducers. I am trying to calculate the instant
...
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Current transformer to DAQ
I'm using a MCC 128 HAT DAQ on top of a Raspberry Pi. I'm reading the output from an AT-50-B10 current transformer that's around the mains cable (UK) that's powering the Pi & monitor.
I'm ...
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Measuring current with a microcontroller
I'm doing a project that involves sensing current. I'm charging a battery and I need to control how much current and voltage I'm giving out.
I thought that it would be okay to use an SCR like a 40tps ...
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Ammeter showing wrong value
I am trying to figure out why the multimeter is not displaying the right current.
I purchased a bayite DC 6.5-100V 0-100A LCD display digital current voltage power energy meter multimeter ammeter ...
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Current measurement with LT6015, simulation doesn't work
I'm trying to simulate high side shunt resistor current measurement using LT6015 op amp, but the simulation doesn't work I'm always having the same output even if I change the current. Can somebody ...
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LTspice simulation of a fluxgate excitation circuit with H bridge driver, Op-Amp and comparator not behaving as expected
Please see the following LTspice schematic:
This is an excitation circuit for a fluxgate current sensor. The inductor L1 models the magnetic core's B-H loop and dimension along with a sensing winding ...
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