Measurements of the current flowing through a circuit

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2
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2answers
71 views

Inductors in series with different currents

I'm having trouble finding the differential equation that describes the circuit, at t=0 10A flow through L1 and 0A through L2, since current can't change instantaneously. But they're in series so ...
2
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3answers
205 views

How much current is a powered-down ATtiny84 supposed to take?

I know this sounds like a stupid question, but I'm wondering if the datasheet has an error or something. I have an ATtiny84 connected to my bench power supply set for 3 volts. It's fused for the ...
0
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1answer
38 views

Three phase motor current verification

I want to verify that the quadrature current through a permanent magnet synchronous motor (PMSM) is actually the same amount as I commanded the field-oriented control (FOC) motor controller to push it ...
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4answers
204 views

How do I average a complex waveform?

I am trying to figure out how long my project will last on a single battery. It's powered by a single AA battery with an NCP1402 3.3 volt boost converter. I've determined that the target circuit draws ...
0
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1answer
43 views

Solar power monitoring with Raspberry Pi

I want to measure the current and voltage from a set of small solar panels (about 10V and 100mA but not settled yet) using a Raspberry Pi. There will be between 4 and 6 panels. This project will ...
0
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0answers
29 views

How to measure the peak current (inrush current) and results assessment

I would like to peak the inrush current of a controller. The voltage input of the system is 24V and the only thing which is available, is an oscilloscope and a variety of resistors. The basic idea is ...
0
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4answers
87 views

Is it possible to power AVR micro project with just one coin cell battery?

My current project setup is: ATmega328P micro with 32 LEDS driven by 4 8-bit shift registers. System without LEDs draws 20mA of current continuously. With all LEDs lit at the same time, it draws ...
0
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0answers
51 views

DC shunt current measuring

I am trying to build DC shunt based high current measuring using bus bar. Each bus bar has a 1000V 20A rating. Is any IC available to measure? I have done with hall sensor based. So my plan to build ...
2
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2answers
197 views

calculating a burden resistor for a current transformer

Background: I follow a reference design for a single phase power meter (230V, max 3A). The below circuit is to measure current via a current transformer. a CT will be connected to...
17
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1answer
643 views

What are the advantages of a shunt resistor vs. a hall effect sensor?

I'm constructing a boost converter, and I need to measure both the input current and the output current. Currents range anywhere from 25A to 200A, depending on the model. My controller is referenced ...
0
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0answers
41 views

Determine current so that you have circular polarization

I have a problem in resolving the first point of exercise on antennas. Note: if it wasn't clear \$\phi_1\$ and \$\phi_2\$ are phase of alternate currents \$I_1\$ and \$I_2\$ I know that to have a ...
2
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3answers
209 views

How to build very low cost current transformer?

Im building low cost home energy monitoring system. I want to see how much energy is used by water heater, big water pump, kitchen equipment, lightning, computer. I would be awesome if I could measure ...
2
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2answers
72 views

Simple PWM regulator, current measurement without high-side current sensing

I have a very simple Lead-Acid battery charger with slow (1kHz) PWM regulator. I would like to add current and voltage measurement (with PIC18F ADC - 200kSPS). I have no problem with voltage ...
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2answers
103 views

Measuring Current Consumption of USB Devices

I was trying to measure the current draw of a USB-powered device (a Raspberry Pi) to determine the suitability of powering from an external battery pack. So I took a USB cable, split the +5v (red) ...
-1
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2answers
204 views

RMS vs DC(mean value) when calculating power of pulsed or rectified signals

When I have either a rectified signal (like the unfiltered rectified sine wave out of a diode bridge) or say a fast pulsed signal feeding a LED and resistor, in which both the DC component and the RMS ...
0
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0answers
85 views

How to measure current waveform in Proteus?

How are current waveforms measured in Proteus? There is a current probe in Proteus but I think it is giving me absurd results. I want to plot the current flowing through a resistor. There is a graph ...
0
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2answers
103 views

Small-value current sense resistor value changes after assembly

I'm using a small value (~60milliohm) and small-package (0402) resistor to measure current. When I probe the resistance with a (nice Agilent) DMM, the resistance is more like 100millohm though and ...
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0answers
24 views

Current consumption estimate for frequency dependent specification

I am carefully calculating current consumption for current budget limited device. Certain switching devices such as integrated opto-isolator gives current consumption specification in a form of X ...
0
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1answer
58 views

Shunt capacitance in applications not involving photo diodes

I have read a lot of articles about how to determine the correct feedback compensation capacitors capacitance in transimpedance amplifier circuits, but they "all" use the photodiode as an example. ...
2
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3answers
109 views

Measuring DC Currents

I developed a board and I like to measure the power for each block. Power can be a few micro amps to a few hundred mAs. (Depending on the block). I have zero ohm resistors at the input of each block ...
1
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2answers
188 views

What is the significance of 75mV in available 100A current shunt resistors?

I'm considering doing part of How to Install an Ammeter in the Black & Decker CMM1200 Cordless Electric Mower but first with just a shunt resistor and voltmeter, versus hooking in a dial ammeter ...
0
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3answers
76 views

AC current transducer symbol

What does the symbol in the red circle mean? (Product page)
0
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1answer
85 views

What is the unit V/V?

I came across this when I was browsing through the data sheets for a current sense amplifier such as the LT6100. It reads: "Fixed gains of 10, 12.5, 20, 25, 40, 50V/V are obtained by simply strapping ...
0
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1answer
94 views

Lightning Connector Power Output rating/ Apple Policy

I am currently in the process of developing an external antenna for smartphones, so the answer of the following question(s) pertains to the feasibility of this product. What is the line level output ...
0
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0answers
58 views

Analog output using a current-output DAC and resistors

Does it make sense to have a 4-20mA output DAC and use a precision (~1%) load resistor to convert this to a voltage output with the goal of having a selectable current/voltage analog output? For ...
0
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2answers
214 views

What's the best MOSFET for switching small currents?

What are the most important characteristics to look for in a MOSFET for switch a precision 50nA load? The MOSFET should be able to switch the load on or off within 1us. The overshoot/undershoot ...
0
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2answers
114 views

Transistor for 4-20 mA voltage drop resistor connection?

This is for converting a 4-20 mA current loop signal to a voltage. Is it okay to connect the resistor for measuring voltage drop with a transistor to allow for switching between voltage and current ...
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3answers
205 views

Working out mAh from current and time

If I know how many millamps I'm drawing, and also for how many milliseconds, how do I calculate this to mAh consumed?
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2answers
97 views

What will be the value of Vo

simulate this circuit – Schematic created using CircuitLab This ckt comes as a question in our previous year exam. what will be current " I " and voltage drop " Vo " . It'll be very ...
5
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1answer
157 views

How to measure car battery current precisely in wide range (starter current, charging)

I want to measure car battery currents in high resolution and in wide range and both directions (including engine start and charging currents). I don't need very high precision measurement, but I ...
2
votes
2answers
140 views

Stepper current measurement puzzle

The basic puzzle: how to conveniently view stepper motor current on a scope? Edit 2014-04-14: More-sophisticated schematic and description. I am building a test fixture to examine the behavior and ...
0
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1answer
102 views

Measuring smartphone's battery State-of-Charge during charging

I'm designing a mobile device that uses a Li-Ion battery. It is required to indicate to the user the State-of-Charge of the battery, similar to how it's done in smartphones. At first I considered ...
0
votes
1answer
135 views

Circuit to provide 0-5 V output proportional to 0-30 A from C.T?

I want to design a circuit to protect oveload current of 30A.I have a controller board(PLC) which accepts the voltage range of 0-5 as an input and C.T with 1:7000 turns which can maesure 0.5 -60 ...
0
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1answer
71 views

High-current monitoring circuit

I have the following circuitry: Battery Supply => Current Monitoring Circuitry => DC Motors Battery Supply: 4AA NiMH batteries - 4*1.2V (1.5mAh * 4) Current Monitoring Circuitry: Max 4378 chip ...
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1answer
147 views

Max output current per I/O pins from Basys2 (SPARTAN 3E) board [closed]

I am trying to drive IR leds out of spartan 3E fpga on xilinx's BASYS2 board. I will be using external current amplifier to drive the IR lEDs with control singal from the FPGA. I need to know the max ...
0
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3answers
91 views

Voltage dip on MOSFET switchable current shunt

I have the following circuit built up in LTSpice which will be used to switch in different sense resistors for current measurements. The mAEn signal switches the M1 transistor on at t=10ms which ...
2
votes
1answer
140 views

Current Transformer giving a reading when not clamped around a wire

A split core current transformers is currently clamped around a live wire. One end of the transformer's output wires are connected to the analog pin of an Arduino and the other end has a 2.5V bias ...
0
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2answers
46 views

Galvanic Voltage and Current strength

This is a mouthful! I have a copper pipe fixed with zink coated (galvanised) saddles. I want to ascertain what the voltage would be in the dissimilar metal galvanic reaction between zinc and copper? ...
4
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1answer
97 views

What determines the frequency range of a current transformer?

Per the title, what physical or construction parameters determine the frequency range of a current transformer? I happen to be looking at these two from mouser, but I'm sure the question is generic ...
0
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2answers
342 views

How to sense current being used by motors

I have an Arduino project that provides 12v power to run motors, etc... I want to be able to measure the current (amps) that the motors are using (0 to 500ma). 12v comes from a battery, but that ...
10
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2answers
384 views

Measuring average current with uC and current shunt

This is my first post. I'm a software guy trying to do hardware so be gentle :) Circuit I'm designing a small circuit (see pic, and sorry for messy schematic) that plain and simply is a bunch of ...
3
votes
3answers
191 views

Using built-in gain on ADC vs different current-transformer?

I'm looking to eventually build an energy monitoring circuit using a raspberryPi as the controller and some type of ADC as the collector. I'm generally following the architecture of the emonTx used ...
4
votes
2answers
257 views

How to measure the PWM current with a DMM

I have a Fluke 87V, which is a True-RMS DMM, and I would like to measure the current in my circuit. I have 2 motors being driven by a PWM so I wonder if the DC current or the AC current measurement of ...
0
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1answer
191 views

burden resistor and/or voltage divider in an energy-sensing CT setup

I want to (eventually) build myself a home power monitor using basic current transformers. While reading on various circuit designs, I've stumbled upon what must be a very basic question. If we look ...
6
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2answers
349 views

Why don't hall effect current sensors exist for low currents?

There do not seem to be hall effect current senors available for small currents, say on the order of 500mA. I'm guessing this is due to some technical or physical limitation. What is it?
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2answers
150 views

Isolation in Resistive Current Sensor

In resistive current sensor, can it have two different supplies for the voltage divider circuit and the differential op-amp circuit? Since the op-amp only gets the voltage difference.
1
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4answers
135 views

Check if electrical current exists in high voltage

I'm thinking about a simple home automation project, containing a Rasberry Pi, a Sainsmart SPDT Relay, I would like to switch the state of a ordinary bulb (ON , OFF) using both the relay and the old ...
1
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3answers
412 views

Home Current Meter - is this a good solution?

I want to build a simple current meter to measure my power usage at home, and have the data sent to my blog's database. (I know there are similar solutions out there, but this project seems engaging ...
3
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2answers
54 views

Current measurement maximum time

On my multimeter I have two current measurement connection. One for the mA and one for the A. On the ampere one there's a time limitation but not on the mA one. Also they mention in the manual a kind ...
2
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1answer
239 views

Measuring the Current Draw from a LIPO Battery

I have been working with LIPO batteries to power my portable projects for a while (mostly in RC aircraft), but when using them, I have always had to guess as to how much charge is remaining. Now, I am ...