Questions tagged [current]

Flow of electric charge - typically movement of charge carriers, such as electrons. Measured in amperes (A).

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What is the optimal current for charging two 12V batteries in series?

I have to charge two 12 V, 184 Ah lead-acid batteries in a series circuit. I have read that the provided current should be the 10% of the Ah rating of the battery, e.g. in this case it would be 18.4 A ...
33 views

TRIAC control of inductive load. Current ringing at higher power causes TRIAC to remain on

Here is the circuit I am using to control the motor. L2 is meant to represent the motor and C3 is the capacitor that comes with the motor. It is a single phase AC motor found here. This circuit is ...
69 views

Is the reversal of time another way to interpret negative resistance? [closed]

Or, restated... What is the correct equation for the reversal of time in an overunity circuit? (Not this equation...) $$Vc=(Vx)(e^\frac{-t}{RC})$$ In this differential equation, the negative current ...
25 views

Repelling charges and current flow

The electrostatic force between two like charges is repelling. This concept is fairly clear to me with Coulomb's law and electric fields. So two electrons will repel each other. Given this statement, ...
29 views

Calculating battery life considering the capacity drops depending on load current (2 x 4 AA-packs in parallel)

This is a very recurrent question, about calculating the battery life given certain circuit current usage. This example will be similiar to this one in terms of the battery used and the consideration ...
56 views

Computer SMPS overload protection and Low current shut down [closed]

What i have : i have a zebronics 450w smps (those generic things like this) . *which is rated for 12 v 15a max *it is a old PC so now I dont need it anymore, so I decided to take the psu out and turn ...
60 views

Meanwell LRS-350-12 power supply spec'ed input current amperage confusion

I have an LRS-350-12 and am trying to understand how much AC current it can draw. Everything I've read tells me it should basically be its rated DC wattage divided by input current, divided by ...
42 views

Electric field in a circuit and potential drop

With reference to the above image: Here the battery produces a constant (will it be constant? pl. explain) electric field across the length of the wire, lets say its value is $\vec E$ . This field ...
43 views

Measuring output impedance of current mirror

I am working on a current mirror circuit using BJTs. I have managed to calculate all the values from the given problem (Sedra book). I am having issues with the simulation. I have calculated my output ...
112 views

How can a current be constant and there still be a voltage drop

I'm having trouble understanding how this can be possible. Obviously, I'm missing something but I'm not sure what it is. The amount of voltage at a point depends on the electrical potential energy at ...
29 views

Source Transform [closed]

I am doing source transformation and I arrived at this setup. Elements in series with a current source can be removed. So should I remove R2,V2,R1 and V1 immediately or should I add first V3 and V1, ...
70 views

How to find the Thevenin equivalent of this circuit?

This is what I've got so far, but not sure what to do from here.
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DC motor: why is torque NOT DEPENDENT on the angle of rotation?

I am reading a book on control systems where they take an example of an armature controlled DC motor. Because the goal is to describe constructing a block diagram from the system equations, the ...
202 views

How does one know that the current is flowing downwards through the $8 \ \Omega$ resistor?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example: Example 1.10 ...
90 views

Make a circuit to make sure a device only gets a maximum of 1A

I'm making my own smart home device with a Raspberry Pi. I will power the Pi on the same circuit as our bell. Now the bell transformer is 8V, 1A and the bell itself uses 0.5A. I'm thinking to replace ...
36 views

Calculate the integral of a saw tooth wave

My question is with reference to this question over here Suppose, I have a saw tooth current source with peak value from 0A to 1A with a frequency of 1kHz and I need to calculate the charge of the ...
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Why is the polarity of the $3 \ \text{V}$ source necessary to calculate the current flowing through the $8 \ \Omega$ resistor?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 1.7 Problem Solving gives the following example: Example 1.10 ...
14 views

Bias Tee scale for current of 500mA, 1A, 2A, 3A, 5A

Before I start excuse my ignorance but I am new to this topic. I have been asked a question regarding Bias Tees. The Bias Tee is supposed to have a frequency range of 1-30MHz and then we need to scale ...
44 views

Effect of Internal ADC capacitor in Microcontroller

The input pin mentioned in the below image is the input pin of the microcontroller. It explains that the internal capacitor of A/D peripheral of MCU should be very much less than the external ...
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Are 4N35 optocouplers clamped at 22V?

I am trying to detect mains with an ESP32, for that I started testing this circuit: I bought a 4N35 optocoupler and 110kΩ resistors. My first test was using 2 resistors in series, so R1 = 220kΩ. The ...
138 views

Average value and RMS value

I am trying to understand the concept of RMS value. From whatever I have read and the tutorials I have seen, I have seen them derive the RMS value only considering the first positive half cycle of the ...
47 views

DC current rating of copper wire (SWG)

I want to use SWG-sized copper wire but I am a little bit confused about the following: On the internet I found different charts with different maximum current ratings for the same wire diameter. The ...
61 views

The current that an AC3 contactor can support

I am constructing an ATS (Automatic Transfer Switch) for a diesel generator with a max current of 300 A. Now I already have an AC3 contactors with Ith = 100 A and I don't want to waste the money on ...
2k views

What is the difference between a linear regulator and an LDO

Can someone tell me what the difference between linear regulators and LDOs is? From what I have read and understood, it is that linear regulators and LDOs don't use switching elements, but I think ...
85 views

How important is it for a device (laptop) to identify wattage of a charger? [closed]

I have several "old" Thinkpads. Recently I came across that Type-C PD mod to replace charge port with Type-C one. Description said: Please pay attention what you order because normally your ...
1k views

With enough copper wire, can I attach one end to one side of a 9V battery, then circle the earth and connect it back?

This is a dead serious question I have not been able to find an answer to: if I had enough wire, could I make electricity pass through if I connected one end to a small 9V battery and then circled the ...
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What is the formula or any method to calculate the value of the output capacitor and inductor in a buck converter

I have using a buck converter whose output is 5V and 1A. Can someone tell me whether these is any formula to calculate the value of the output capacitor? Like, without involving the switching ...
111 views

Why is there EMF present when there is no current?

Current means the rate of flow of charge. Electrons are the ones that carry charge in current. From the definition of EMF (electromotive force), When no current is drawn from cell, the potential ...
33 views

Sensor for car AMPS while starting and not running

I'm building a data logger with a PIC18F27K42 and almost everything is complete. What I'm a bit stuck is with the sensor. I bought a Dodge Journey 2012 and as I understand in there posts regarding a ...
132 views

What does charge on an electron mean?

As I have read , charge is electrons , protons or neutrons. Now , according to definition of current , current is the rate of flow of charge I.e flow of electrons. Then , I=Q/t . Unit of Q is coulomb &...
102 views

Is a battery pack connected parallelly or in series?

I have a circuit of a battery pack of 4 18650 and a 4S BMS. See the picture below. The question is: is my understanding correct that this circuit means that the batteries are connected in a series, so ...
80 views

What is the current flow in a GPU? [closed]

Today, I was playing GTA 5 on my laptop. In the performance tab, I saw that my GPU(GTX 1650 with Max-Q design) power is 34 Watts and the voltage of GPU is 0.8v. So, according to P = VI, I = 42.5A. I ...
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Calibrate current amplifier for using with Arduino

Many months ago I design my own voltmeter and ammeter for using with Arduino. Now I need to calibrate the ammeter part that use a current sensor amplifier (MAX9919NASA+) https://www.mouser.com/...
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If a BMS has a limit 40 A, it means that power supply should have maximum current less than 40 A or that power consumption should be less than 40 A?

For example, my battery pack can provide up to 40 A. Can I use BMS 15 A, if I know that the power consumption of my components is certainly less than 15 A? And if my power consumption is more than 15 ...
922 views

What is the input and output current of the GPIO pins of a microcontroller?

I am trying to find the current sunk and sourced by the GPIO pins of the STM32G030 (STM32G030x6/x8). It says on page 40 of the datasheet: The output current sunk by any I/O and control pin When it ...
42 views

Why do they call it alternating current (AC) not alternating voltage? The same goes for DC instead of DV (direct voltage.) [duplicate]

This takes me to my college studies 4 years ago. My teacher taught us that there is AC and DC electricity alternating current and direct current respectively. I also drew a graph for voltage and ...
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PTC Resettable fuse

I need to limit the current of a motor to around 1A. I would like to use a PTC fuse so that it trips in the rare occasion the motor is forced by the user to draw too much current because the motor is ...
77 views

How do I choose currents through my circuit?

Beginner here. I've recently "almost" finished a project in which I am using a relaxation oscillator to get a square wave output with a certain frequency. The circuit works as I wanted but ...
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Basics of batteries [closed]

What are the electrical properties of a battery besides its internal resistance? Does it have any capacitance associated with it? What makes a battery different from other electrical or electronic ...
84 views

Is this simple circuit correct?

I made this circuit for my school (they are going to use it if it all works on an open day) so could be nice if it does. Would the motor rotate anti-clockwise (so if battery was normal way around it ...
29 views

Effect of connectors in wire load rating

I understand a bit about voltage, current, resistance, power, etc., and I know that thicker wires are able to allow more current to flow in them. I also understand the concept of voltage drop across a ...
122 views

How does the current source work?

I am reading an application note and find a current source circuit as the following. Why the lower AD8610 is needed since the output voltage of the upper AD8610 is determined by VIN and the two 2kΩ ...
141 views

Can you exceed the maximum current rating of an IC? [closed]

I am still new to electronics so please note that I am still a bit confused about current/voltage etc. I have a 74199n Shift Register by Segnetics and on its datasheet it says that the maximum input ...
104 views

This conducts both ways. What is it? [closed]

What is this? It conducts both ways.
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Will powering a device with a source that can provide more current than the device needs damage the device? [duplicate]

I am trying to build a power supply for my LCD monitor. It consumes 19.5V and 1.7 amperes. I am using a 12 volt 16 ampere lead acid battery. I have used a step up boost converter to increase the ...
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Why does the short circuit current increase when we connect a distributed generator?

I read that the short circuit current increases when we connect a generator to the grid. Why? Is this true for any kind of generator? (PV, wind turbine, synchronous generators, etc.)
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Are voltage harmonics critical in the electric grid?

I'm a student of Politecnico di Milano and today my prof during the lesson told me that it's important to limit current harmonics into the grid and not voltage harmonics because these last do not ...
83 views

Switching 3.3V 150mA efficiently

I have a load (from 20 LEDs with 20 resistors) that I want to switch on/off as a single block, using a GPIO pin from a micro-controller. I have measured the current to be 145mA at 3.3V Vcc. simulate ...