Questions tagged [electrical-engineering]

Study and applications of electricity, electronics, and electromagnetism. Use this tag when someone who has trained as an electrical engineer is likely to be able to answer your question.

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67 views

If the water flows at a pace of 10 cubic meters per hour, how much electricity can a micro hydropower system produce?

The diameter of the recipient through which the water is passing is 10 cm. LE: There is no height involved, but depth, as a matter of fact. Let's assume that there is a 100 meters deep well, which has ...
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1answer
49 views

Definition of Bandwidth as angular frequency

I am searching for a Formal Definition of bandwidth given the transfer function of a system, or the bode plot. Is it the frequency $\omega_b$ in which $$20log|H(j\omega_b)| = -3\text{dB}$$ or $$20log|...
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Can I use a PWM motor regulator to control a LED string?

I recently bought some LED Christmas lights, but they are too bright. So I was thinking that maybe I could regulate the output by using a PWM regulator? My LED lights have an output of 30V from the ...
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1answer
41 views

Control Systems: 3rd order system project [duplicate]

I'm in need of help finding a third-order or higher system in which I can derive a transfer function. We have a class project in which we need to find a real-life example of the system that equates to ...
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13 views

Simulink Matlab active, reactive and apparent power procedure? [closed]

I would like measure the active reactive and apparent power on a nonlinear load by Simulink. Is it possible or not? What is the procedure?
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30 views

Implications of different LCD tecnology

https://www.techspot.com/article/2322-display-tech-compared/ I appreciate that IPS panels use a parallel alignment of crystals and they rotate, while VA panels use a vertical alignment and they tilt. ...
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2answers
51 views

Angle of incidence in concave mirrors

What happens when you change the angle of incidence(normal to the mirror)? How does the angle of reflection change? Is it invariant?
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4answers
38 views

Time period of charging a mobile phone via car

As car batteries provide only 12 V instead of ~230-250 V, I assume it takes much longer to charge them compared to a common wall socket?
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1answer
20 views

Is there any way to sense whether a mains DAB radio is currently turned on?

I’m looking for a way to discern whether a DAB radio plugged into a non-smart electrical outlet is switched on or off. Note that the radio is constantly plugged into a live socket, there is a power ...
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1answer
63 views

Can magnetism exist apart from voltage? [closed]

A type of electrical amplifier is proposed in which only magnetism and it’s analogous current exists for the most part. There is no voltage and no wattage (to speak of) in which electricity has to ...
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2answers
58 views

Is "efficient wattage" a correct term?

I'm an engineering student studying for the proofreading course I'm taking. In one of the practice sets there's a sentence that's been marked correct but the bold italicized words just don't make ...
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How to transform the mains from 110 V to 220 V and do proper grouding for house on limestone rocks near the ocean? [migrated]

I would like some guidelines and advice on how to transform the mains supply from 110 V to 220 V for an entire house. This means the wall outlets should permanently deliver 220 V instead of 110 V (...
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1answer
111 views

Can a battery-powered electric vehicle be driven through a dust storm?

I would like to know if a battery-powered electric vehicle such as a Tesla Model 3 automobile can be driven through a dust storm. Back during the Dust Bowl days of the 1930s, driving through a dust ...
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24 views

Generation of Electrostatic induction

I need to generate a 500 volt electrostatic charge. How can I do this? I don't have a Van de Graaff generator. What are some practical suggestions? Basically I want to do experiment in which I need to ...
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0answers
66 views

Are all boost converters isolated?

I have a few boost converters(3-6V to 40,000V) and I want to connect them serially. link In order for them to be connected, they have to be isolated. Is there any way to check that? If they aren't ...
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1answer
35 views

Power systems unclear voltages

I was looking at this problem: "A balanced delta connected impedance load with (12+j9)Ω per phase is supplied by a balanced three-phase 60 Hz, 208-V source " I do not wish to ask for help at ...
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1answer
49 views

Line to neutral voltage in three-phase power systems

I have the book "Power system analysis and design" by Sarma. In his intro to balanced LN voltages, in chapter 2 p62 he states: $$V_{LL} = \sqrt{3} V_{LN} \angle30º$$ but later in the chapter,...
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3answers
57 views

Question about how to study for engineering university exams [closed]

What are some of the ways to predict exam questions from class lectures in university final exams? How should one understand the mindset of the professor & find out important maths/questions he ...
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3answers
91 views

Rotary Phones vs Pushbutton -- why did we ever have rotary?

I remember when we first got pushbutton phones -- I would say user experience is literally ten times better -- if you used a rotary phone extensively as part of your job, you would rapidly develop a ...
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1answer
37 views

How to know which opto-coupler is suitable for high current application?

I would like a suitable opto-coupler to use as isolation from a 12V and around 30A current and another for 5V and around 30A. Are there any good opto-couplers for those ratings?
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1answer
72 views

What fraction of energy is typically lost in transmission over power lines?

Energy transmitted via power lines necessarily undergoes some degree of attenuation. The question is, how much? This source, screencapped from this video, says: But, I've heard via word-of-mouth from ...
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3answers
100 views

Magnetising a needle with static electricity using silk cloth

A nautical navigation textbook on my table says that we can magnetise a non-magnetised needle by rubbing it with a silk cloth. I decided to cross check on the internet, and found some experts calling ...
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0answers
28 views

4-wire resistance measurement suitable range

First, the task is to measure surface resistivity of solar cells to monitor the surface degradation. I am testing some measuring function and accuracy by putting a simple 31 kΩ resistor in the circuit....
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1answer
40 views

How to find the torque required to rotate wooden slab

How can I find the Torque needed to rotate a wooden slab with no weight applied on either end of the slab if I have a servo motor placed at the middle of the slab?
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28 views

Whats the best way of connecting these multiple coax cables?

I am building a double cross antenna where I have to connect four different dipoles together like in the picture below. I'm somewhat new to this and I'm not sure what the best way of doing this is. ...
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Is there a way to output a variable from matlab simulink function block and use it to specify other parameters?

This function block outputs 'phase' which I then want to use as a variable like this: But as you can see simulink throws an error. I tried using Simout but it doesn't work. I am sure I am missing ...
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3answers
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Could the analogical input and output of the minijack on smartphones be used to mesure temperature via a type K thermocouple?

I'm an advanced industrial engineering student and I'm currently looking for some "final project" material. I have this idea of a product where you can plug in a type K thermocouple at the ...
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1answer
17 views

Transformer secondary conductor protection: how do NEC 240.21(C) and NEC 240.4(B) make sense together?

NEC 240.21 says all ungrounded circuit conductors require overcurrent protection, with a list of exceptions: One of those exceptions is 240.21(C): 240.4(B) says that if you're under 800 amps, you ...
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1answer
24 views

BLDC motor electrical constant in Vms/krpm?

At this random motor shop and elsewhere (in the results of STMicroelectronics' motor profiler), I find a Ke constant expressed in Vms/krpm. If this were Vrms/krpm, I would guess that "rms" ...
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2answers
38 views

Precisely control voltage output

I think the component name is a rheostat- is that what allows you to control the voltage output please? I want to control it in steps close enough to 0.1 ish volts? So I would like to attach a knob ...
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1answer
45 views

Controlling Motor Rotation

This is my first question / post here. I have just begun researching motors and how they work, as they are necessary for a personal project. I want to know how to control a motor so that it only ...
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2answers
178 views

What is the reason behind the alternating polarities in an electromagnetic rail brake utilizing eddy currents?

The design of electromagnetic track brakes has alternating polarities in order to increase the effectiveness of the braking force. What is the fundamental reasoning behind this increased effectiveness ...
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0answers
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Voltage drop on amplifier signal after LED switches on

Circuit above shows my design for amplifying PIR sensor signal, which I then feed to Arduino and based off this signal I switch a LED on. Both, the LED and PIR sensor, are on the same voltage rail (9V)...
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1answer
53 views

How to Supply two different DC voltages using High Current

I'm trying to function a 12V stepper motor(>2.5A) and five 6V servos(>3A). Are there any reliable circuits that can output both these voltages and a high output current since there will be some ...
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1answer
50 views

How do mobile phones produce signals?

Normally it would require alternating currents to product electromagnetic waves. Yet as mobile phone is powered by batteries which only produces direct current, what type of mechanism/structure allows ...
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1answer
65 views

Battery size and maximal power output [closed]

Generally how does the size of the battery affect its maximal power output(together with other factors like materials, for instance)? Under the current engineering technology and with any possible ...
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1answer
75 views

What is the maximum distance for eavesdropping? [closed]

There is a closed question https://physics.stackexchange.com/questions/276667/what-is-the-maximum-distance-for-eavesdropping-sound-waves on Physics Stack Exchange and I thought this might fit better ...
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0answers
89 views

Devices powered and charged via electricity generated by human body

I came across articles like: https://www.sciencedaily.com/releases/2021/02/210210142049.htm https://pubmed.ncbi.nlm.nih.gov/27836601 and https://www.dailymail.co.uk/sciencetech/article-2004801/Weve-...
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23 views

Is fiber to computer(without the use of LAN cables in between) possible?? Are any further developments getting carried out towards this goal?

All of us know well that the fiber to home(FTTH) connections are a trend nowadays. Every nation is planning to replace the existing metal wires with optical fiber cables. But we also see that the ...
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1answer
66 views

Drawing nyquist diagram by hand for a system with time delay

how can I draw the Nyquist diagram of Kexp(-Ts)/(s*(s^2+s+a) by hand for different a and K values and examine the stability of the system depending on T value? I drew for the case with no time delay ...
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1answer
61 views

Type of Engineer [closed]

I am a mechanical engineer by education (master's degree). I have been working for 6 years in industry. However, I am beginning to search for a new job. I work at NASA as an instrumentation engineer. ...
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3answers
109 views

Is electric motor torque determined by Kv or by power (watts)

I'm trying to size a motor for an e-bike, but I'm confused as to what motor parameters determine the maximum torque that it can output (Kv or power in watts); I've found the following formulas: Power (...
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2answers
59 views

how does the rotary motion in a turbine convert into electric energy?

from what I understand ( please correct me if I'm wrong) the turbine is connected to a magnetic thats being surrounded by copper wire and when the tge wire go from being affected by the magnet to ...
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0answers
33 views

How much electricity does it take to polarize specific types of insulators?

as I hope you know, electric polarization is when you put an insulator in an electric field, and the nucleus and electron cloud go in an opposite direction. https://www.priyamstudycentre.com/2020/02/...
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2answers
487 views

Amp-Hours vs Volts in electric chainsaw specifications

Can someone please explain what I am losing/gaining in the trade-off between Volts and Amp-Hours when buying a piece of equipment such as a chainsaw. I'm currently comparing two items. I'm making this ...
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5answers
81 views

How can I add the torque of multiple gears?

If I have 3 gears meshed with a gear in the center of the 3 gears as shown in the picture. all of those 3 gears are connected to different power sources. They are free to rotate in the same direction ...
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3answers
43 views

AC/DC Laptop adapter power losses

I have a laptop power adapter shown in the picture below. It is written there 170Watt INPUT: 100-240V ~ 2.5A OUTPUT: 20V 8.5A I believe for AC Input they mean Root mean square voltage/current. for ...
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0answers
28 views

Valve solution for mixing external air into a closed loop climate controlled air circulation system

I'm looking for an electronically controlled air valve solution which would provide a way to mix external air into a closed loop air circulation system used for climate control in an enclosure. The ...
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0answers
36 views

Circuit analysis

enter image description here I don’t understand what is the Use of ‘Vin’ as its anode connects to the open circuit.So I can’t even solve QA
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3answers
179 views

If a control system is unstable does it mean it will oscillate?

When a plant is known to be unstable, does it mean it will have an oscillation response?

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