Questions tagged [current]

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

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135 views

How is powering an LED with a 9 volt battery possible without burning the LED?

I used a 220 ohm resistor with a 9V battery and the LED works fine. However, most sources say the forward voltage in a red LED is typically only ~2 volts. Going by this logic, the LED should have ...
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2answers
50 views

Battery mAh and device operation

If a small signal electronic load is designed for normal operation by using say 1.2 V 630 mAh battery and if the same battery is replaced with say 600 mAh or say 700 mAh rating battery, does it affect ...
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1answer
77 views

Current limiting circuit

Kindly suggest necessary change to be made for current liming circuit for buzzer. simulate this circuit – Schematic created using CircuitLab
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1answer
41 views

Using a Main Surge Protector for only branching out other surge protectors

Whenever I try to find information about this question it always says that it is not good to plug in a surge protector into a surge protector because you can overload or overheat the protector or ...
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56 views

Why does moving this ammeter change the polarity of the applied voltage?

Note: I'm not an electrical engineer, I'm a materials engineer. So maybe this question has an obvious answer, but I couldn't find one with a Google search. I also have no idea if I tagged this ...
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1answer
35 views

Get expressions of E and H fields at a boundary from expression of surface current - Pozar ex 1.11

I am bringing whis question because, even though I have the solutions manual from the exercises of the book "Microwave Engineering 4th edition", by David M. Pozar (one of the Bible books for microwave ...
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1answer
79 views

Will 2000A Inrush Current Damage Outlet Circuitry?

First time building an AC control system complete with motors, PLC, sensors, power supplies. All this is sourced from a 220VAC outlet. I have calculated the total current draw of all motors, powers ...
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2answers
51 views

PIC16F88 digital output to gate of MOSFET - Voltage / Current questions?

I'm new to electronics. If I say anything that's presumptuous or just flat out weird or wrong, please point it out. There are many gaps in my knowledge. I'm working on a simple personal project. I ...
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3answers
49 views

Brushless DC motor values at voltage other than nominal

I am currently using a maxon three phase BLDC motor (datasheet PN:412825) that is rated for 48 volts (see spec sheet below). I am running the motor at 18.5 volts (requirement for my application). I am ...
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2answers
84 views

Are current and voltage orthogonal in a transmission line?

If there is a phase difference on a lossless transmission line between current and voltage, is it always 90deg? Assume the Load matches the transmission line characteristic impedance. If not what are ...
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3answers
51 views

Is the maximum current a resistance can draw limited by the maximum current available (current rating) in the power supply?

Let's say I have a single phase power supply at 100 V and 10 amps at my wall outlet. If I were to connect a very low resistance element (say 0.1 ohms), using Ohm's law I could say the resistance draws ...
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1answer
82 views

How can a light bulb run on different voltages (USA and EU)?

There is a concept in EE I don't understand. In Europe we have a 230 V supply voltage and in the USA e.g. 120 V. Now the thing I don't understand, how can I use my charger( or a light bulb) in ...
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22 views

High-torque low-speed switched reluctance motor: design Features

I am studying the design of high-torque and low-speed switched reluctance motors (SRM). There are classic designs (8/6, 10 / 8,12 / 8) and designs with multi-toothed rotors and with additional teeth ...
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25 views

powering a ESP32 with less current than specified [duplicate]

I'm building a device that uses an ESP32 + some LEDs + some 74 ICs. It might require 150~200 mA. I want to power it from an old computer (specifically, and Commodore 64) that says it can give 100mA. ...
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4answers
1k views

Can a DC brushless motor produce the same torque at different power levels?

I am looking these Neo Brushless motors for a project. Here are the links to the data sheet and also to stall testing from the company: http://www.revrobotics.com/neo-brushless-motor-locked-rotor-...
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3answers
47 views

LED Brightness or Luminance is additive or not?

Let us say I have an LED whose brightness or luminance value is 50 Cd/m2. If I lit 10 same type of LEDs with same conditions of current and voltage then will the brightness of these 10 LEDs will add ...
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22 views

Smart High and Low Side Mosfet

For example I have two smart high or low side mosfet that have 4 channel. One high side driver has 1 amper per channel. Other high side has 2 amper per channel. I tested these smart high side mosfet ...
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28 views

How to select power source for robot actuator with known torque requirement

I am building a robotic actuator that will be backdrivable, this robot will have pretty low RPM. I will be using brushless DC motors. I am trying to figure out requirements for the power source. I ...
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2answers
48 views

Finding a current in a given circuit

The problem has given the following circuit: And asked to find the value(s) of Ix if the elements absorb the power(s) given. I tired to set up KCL/KVL but I keep getting stuck. I first drew this: ...
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1answer
131 views

Voltage Controlled Current Source - help needed

I am designing a voltage controlled current generator for the currents in a range from 0 - 2.5mA. The load resistance is within the range of 0 - 5k Ohms. I decided to go with difference amplifier ...
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3answers
145 views

What causes a thorn like feeling when your put your hand in water in electronic appliances?

I live in India, the voltage supply in houses is 220V. Sometimes, for example in my washing machine, when it is full of water and I put my hand in it, I get a feeling like a thorn/tiny nail is ...
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70 views

Does current in neutral wire flow like this? [duplicate]

I've read neutral wire in 1 phase AC at home has almost 0V at both ends. But still current flows through it. So I've assumed 0.1V potential at the other end near a resistance (bulb). Now there's a ...
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1answer
87 views

Why do we not get shocked by neutral wire and how can it behave as it does? [closed]

I read some articles and watched videos regarding 1 phase and 3 phase ac. And later found that for most home appliances we need 1 phase ac. Then I came to know about live and neutral wires. Few ...
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50 views

CC/CV buck converter with a micro controller

I am using a arduino to fire the mosfet at 62.5KHz and the feedback pin will go to the analog input of arduino I found this schematic on ti page saying "discrete implementation of a CC/CV converter" ...
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1answer
55 views

Current Consumption of CANbus (CANH and CANL)

I'm looking to use the SN65HVD230 CAN transceiver but had a question about the current consumption. Datasheet: http://www.ti.com/lit/ds/symlink/sn65hvd230.pdf In table 8.3 Recommended Operating ...
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1answer
70 views

What is the formula for calculating the no load current of a 3-phase motor? [closed]

I am looking for the formula, not a rule of thumb. Is there a way to calculate the no-load current?
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30 views

How to connect multiple sensors to single PLC input?

Hello. I have a scenario where I have multiple PNP "error signal" from several sensors (let's assume 3 for now). If the sensor output is HIGH, then there is error. If the sensor output is LOW, then ...
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2answers
45 views

8051 LCD interfacing works in Proteous but doesn't work in hardware

I'm working on this project using an 8051 micro controller (AT89S51) and it involves interfacting with an LCD. The schematic of the project I'm working on is shown below: And I've written a very ...
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1answer
32 views

Finding out the accuracy of the current probe's measurement

As part of power supply testing we are measuring the current profiles of various regulators. Startup profiles includes current bursts with different current amplitudes and widths. i want to ...
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2answers
63 views

Simple questions about current flow and superposition

So I was doing this exercise to prepare (not homework, school hasn't even started yet), and I think I got the math and the logic right, but there are a few things that I didn't understand, and since ...
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3answers
162 views

Inconsistency in Values of Laplace Transformed Current when Changing Units

I was trying to convert the units of the following current in Time Domain and Complex Frequency domain (s-domain): $$ i(t)=20\cdot e^{-t}H(t)\,\,\,\,\,\text{[mA,ms]} $$ Where \$\text{[mA, ms]}\$ ...
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41 views

AC capacitor current spike

I was experimenting with capacitor voltage divider circuits but something unusual happened. Circuit is really simple , I connected 100uF 16v capacitor into 13.85V 50hz AC supply Xc is 26.5 ohm So I ...
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2answers
163 views

Why does the measured current differ from the calculated current in this circuit?

I have the following schematic: Now I want to know the (more or less) exact current flow in my circuit. For this I did the following calculations: I = V / R I = 5V / 330 Ohm I = 0.015A = 15mA So ...
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3answers
41 views

What is the current limit of driving a linear actuator for 4 VDC at 12 VDC?

Please bear with me, if this is a stupid question. I obtained a linear actuator of a family of linear actuators, here are the specs ...
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4answers
126 views

Power supply circuit for a PIC16F88 Microchip

I'm coming from the world of software, where I feel quite at home - I spend a lot of time writing code. I do not feel at home in the world of electronics and designing circuits. I really REALLY would ...
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51 views

A4988 current limit formula: Where does the constant “8” comes from?

I am trying to calculate the VREF for my A4988 and while my A4988 is not from pololu I am using their formula over at https://www.pololu.com/product/1182 to calc the current limit. The formula used (...
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1answer
46 views

Minimum Current for Zener to Clamp Vgs of Mosfet?

simulate this circuit – Schematic created using CircuitLab When it comes to zener diodes I find it hard to get information about minimal currents needed for it to breakdown so I thought I would ...
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1answer
43 views

Question about feedback in a current reference

I'm studying the following Vbe-based current reference: The author of my book says: Observe that the circuit has two feedback paths around the gain stage. One positive, the other negative. ...
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33 views

Question about current reference

I'm studying this thermal-voltage-based current reference: The working principle is simple: M1 and M2 form a current mirror which generates two equal currents I1 and I2 (assuming M1 and M2 equal). M4 ...
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1answer
63 views

Current Source Biasing with Diode Load

I am trying to replicate a circuit I found in the Art of Electronics (3rd Ed, page 229) but I am having issues. My load is a LED (Vf=~2.5V) and using a BC237 as the PNP (measured Vbe=~.675V). Using R=...
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1answer
24 views

Current on each winding of a solenoid and wire selection

While I was reading an article about inductors and air core solenoids in general, I came across the term voltage per turn. Until then I thought that all of the windings of a coil are a continuous wire ...
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1answer
42 views

Is that any best way to measure High side mosfet drain current?

To be specific, I am using 6 MosFETs (for ex. PSMN030-60YS) to drive an inductive load. I want to measure drain current of High-Side MosFETs. The way I am doing right now is by lifting the MosFET ...
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1answer
44 views

Polarity of the voltage drop on inductance

We know from the Lenz's law that the induced voltage on an inductance has the polarity that determines an oppisition to the variation that has generated it. But in circuit theory the inductance is ...
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1answer
68 views

Self Biased Current Reference

I'm studying this circuit: The author of my book says that the purpose of this circuit, called "Self Biased Current Reference", is to generate a current almost independently of the supply voltage. He ...
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5answers
673 views

Why is it not possible to create electricity by forcibly putting electrons into the system and closing the loop?

Why is it not possible to make a device operate by forcibly putting electrons into the system, closing the loop, and having electron repulsion do the job of making charge flow? Making electrons flow ...
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2answers
76 views

Is the direction of an electric field opposite to the direction of a current?

I consider electricity to be an observation of the property of electron mobility. If electrons go the opposite way of the electric field, what is the connection between the electric field and an ...
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2answers
88 views

Increasing output current of DAC

I have an application where my Arduino is controlling a mcp4725 DAC for a design replacing a sensor on an old car. The DAC provides the analog output voltage, .25V to 4.9V to the computer. I recently ...
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0answers
29 views

Charging a device with a power bank [duplicate]

So my device has an input of 5V 0.7A, but the cable isn't detachable from the plug so I need to use a different USB to micro-USB cable. My power bank can output on 2 ports, DC 5V 1A and 5V 2.4A If I ...
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2answers
72 views

Electric current in mic

For a typical mic a singer uses in a concert, how much current is generated when the singer sings? The current transmitted from the diaphragm into the wire. What does the following specification tell ...
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2answers
68 views

Current Mirror Gain 1.5 with discrete components

I was trying to simulate the circuit mentioned in https://wiki.analog.com/university/courses/electronics/text/chapter-11 under paragraph 11.4.1. I need to make a current amplifier with a current gain ...