# 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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19 views

### Making Silicone Rubber Surface Conductive

Hey Engineering Community, a physicist this side. I am tinkering on a project where I need a local deformation of the thin sheet(0.2mm thickness, 25cm*20cm dimension); pressing on the surface from one ...
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### Why are there no UPS power supplies that use an external Automotive battery for storage?

What I've learned: A: UPSs generally use sealed lead acid batteries, which use a slightly higher voltage to charge. Using an auto battery will result in the battery being in a slight state of ...
32 views

### How is the city power grid routed and connected to individual locations such as houses?

I'm an electrical engineer but I don't know enough about the power distribution grid or civil. I'm no electrician either. My initial question is how does a new construction, like a home, get safely ...
16 views

### How to check if a USB conector is broken

Suppose we want to check that usb port is working. we can do the continuity test with a multimiter.We connect the positive part of the multimiter to positive part of the connector and we do the same ...
26 views

### Fixture to hold and deliver current to crystal cathode in vacuum chamber

At my internship, I have a small crystal (about 5-8mm long by 2-5mm thick) that needs to be mounted in a vacuum chamber (which is 35mm on the inner diameter) to serve as a cathode with 1.0 to 1.5A of ...
1 vote
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### Find the equivalent resistance between the points $A$ and $B$

In the figure shown below, find the equivalent resistance. I know I should add my attempt but I don't know how to approach these type of problems. This isn't the standard series-parallel combination ...
16 views

### Battery thermal loss

A copper bus bar is subject to a short circuit current of 500 A for 10 s. The section of the bus bar, through which the current flows, has a length L = 50 mm and a cross section of A = 20 mm^2. ...
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359 views

### Will a bare wire encircling a tent and connected to a tall metal rod help to protect the tent from a direct lightning strike?

I am planning to go camping later this month and I am concerned about lightning since the campsite I will be staying at is located on flat terrain in a rural area in Illinois. This campsite is located ...
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### What are the criteria for selecting CTs in a power system?

In powersystems how can we select CT's whith dinite sepecifications? for Metering and protection systems
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### RF MEMS (Radio Frequency Micro-Electro-Mechanical Systems) Switches

RF Reflection Damage. What would the artifacts at the contact beam areas looks like under a SEM examine? More like arc damage or diffused or have a burned thermal damage appearance? Thanks Charles ...
32 views

### Closed loop motor speed algorithms

TLDR; looking for algorithms to control a motor. I have a near-random torque, a battery current that can destroy my motor driver, and I aim for a stable output speed regardless of torque. My inputs ...
22 views

### Can i use a metal gear servo motor to lift a 4kg load and then attach it to an actuator?

I am doing a project if which i am trying to resemble some muscle movements of an arm and i want to attach an actuator to a motor. But i don't know if a metal gear servo motor can lift that much load. ...
20 views

### Using a multimeter in the Wheatstone circuit

If I make a Wheatstone circuit and connect it to my multimeter, power supply and strain gauge; I would need to read off the voltage output and then calculate the strain resistance according the ...
1 vote
49 views

### Curious about the math portion of subjects

I am a long time civil engineer. But I am interested in learning electrical electronics engineering and lately have been teaching myself about analog electronics, signals, digital electronics... One ...
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### Unable to calculate Thevenin resistance

I have to solve for the Thevenin Resistance for the following question and I am unable to do so. Any help is much appreciated. When calculating the Thevenin resistance, I shorted the voltage source. ...
42 views

### Resistance of a pressure sensor from Wheatstone bridge

How do you get the resistance value from a calibrated Wheatstone bridge circuit? I want to build a Wheatstone bridge to get the resistance of a pressure sensor. The unknown resistance in the ...
1 vote
49 views

### Converting string vibration to electricity

Is there a device that can use the energy from a vibrating string (i.e. guitar string, etc.) to produce enough electricity to power a small LED?
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1 vote
61 views

### Can I perform a hard reset of a USB flash drive?

I don't typically post to engineering but I need help with a USB drive. First off, I have a USB, a Sahara 128mb, that once became unusable on windows machines, and I thought it was dead. Yet I kept it ...
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10 views

### Double Junction MS Contact

How can I deal with a double MS Junction? the problem is there are thin Si sample with two metallic contacts on side. and the N type doping at Si is ND=1015cm-3 everywhere. Schottky barrier height of ...
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1 vote
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### Relationship between parameters in MOSFET in CS configuration, voltage divider biased

I have this question. I have calculated ID, since power budget is given, ID is a simple P/VDD. Using the ID, RS can also be calculated since it's given that there is a voltage drop of 400mV across RS. ...
1 vote
19 views

### IEEE1451.4 Standard, ConRes + ConRelRes Datatypes

I was wondering if someone could shed some light on the ConRes and ConRelRes data types that are listed in the IEEE1451.4. I am interested in writing a table for a bridge sensor (template 33). So for ...
20 views

### Can this new AC motor/generator design work?

I'm currently in the works of developing a vertically suspended flywheel, and I'm trying to figure out the best method to convert rotational energy to electrical energy and vice versa. I don't want to ...
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### Is the electrical grid a centralized, decentralized, or distributed network? Which type is most efficient?

Is the electrical grid a centralized, decentralized, or distributed network? Each dot represents a generating station, consumer, or relay of electricity: Which type is the most efficient (has the ...
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1 vote
71 views

### How to calculate the torque disturbance of an unbalanced flywheel?

I would like to understand how an unbalance of a flywheel affects the dynamics of a simplified mechanical model. Assuming that the mechaincal dynamics can be modeled as (neclecting inertia of the ...
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### How do I select equipment for a load management system of EV chargers?

In a student project, I need to design a EV-charging system for a domestic high-storey building. As there is not enough loading(the charging stations are connected to tenant supply of multiple floors),...
22 views

### 40A mcb. 40A per pole or 40A altogether?

If I have a 40A 3 pole Miniature Circuit Breaker ("mcb"), does this mean 40a per pole or 40A altogether? The quality standards made me write some more so I do it.
35 views

### How do I calculate the thrust output of a high bypass turbofan engine? (7th grade)

I am trying to create a small version of a high bypass turbofan engine but I can't seem to find any materials that show how to calculate thrust but on a 7th grade level. If anyone here can help me I ...
25 views

### Connecting logic gates with transistors

I've been trying to create different parts of a basic 4 bit computer with transistors like a 4 bit adder, 16 bytes of memory, and registers but when I tried to make a 4 bit counter I failed to find a ...
26 views

### Three-way energy harnessing device engineering

I have a question regarding a certain engineering of a such device capable of harnessing energy in such three way. So, what I want to happen is to implement a solar and motion energy harnessing. The ...
26 views

### Total electrical resistance of a material across different cross sectional area and temperature

It is given that the electrical resistance of a material is: $R = \frac{\rho l}{A}$ Where $\rho$ is the electrical resistivity of the material, $l$ is the length of the traversing current through the ...
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1 vote
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### Seeking Manufacturing Advice: Low-Dose Powder Dosing Device

Hi everyone, I'm working on a project that requires a device to dispense a very small amount of powder (around 1 gram per second) in short bursts. Ideally, the device would "sneeze" the ...
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32 views

### Seeking Assistance with Solid State Relay and Arduino Nano Power Failure Solution

This is my first time, and I'm looking for guidance on my approach to a particular problem: ensuring that a Solid State Relay (SSR) closes whenever my Arduino Nano loses power. The SSR, powered by the ...
67 views

### Error code in the automatic door system

The automatic door lock system malfunctioned due to an electrical surge. Currently, the door is closed but the screen shows the door open. We opened the door by pulling the motor handle and putting ...
18 views

### Why isn't my valve controller not providing sufficient amount of voltage to my fan?

We're using the valve controller below to control the speed of a (generic) fan: https://products.axiomatic.com/viewitems/valve-controls/can-to-4-outputs-valve-controller Problem: We're supplying the ...
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39 views

### How to measure the rotation direction and speed of a ring on a finger?

I am trying to create a device that can measure the rotation of a ring on a finger. Basically there's going to be two rings on the finger, one that rotates and one that is stationary. The idea is that ...
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50 views

### How to calculate the distance between cable supports, considering the weight and other factors?

I am designing a cable infrastructure and have come across the question of calculating the optimal distance between supports for cables. What formula can be used to determine this distance, taking ...
215 views

### Mesh Size and Thickness for Faraday Cage?

I've been considering a double faraday cage of 1/4in 23-gauge wire and 1/8in 27-gauge wire. With this setup would the 1/4in on the outer shell and 1/8in on the inner or the 1/8in on the outer shell ...
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1 vote
33 views

### Strange inverter PWM output signal at startup

I’m monitoring the output of a 3-phase inverter with an oscilloscope, the inverter is a Siemens Sinamics V20. I see that when I enable the power output of the inverter, I have a strange sequence ...
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84 views

### How to calculate the RPM required from a DC motor in order to pull an object that is attached to wheels

I am attempting to make my first project idea of using a DC motor as a winch motor in order to pull an object, I am using string as the rope to pull object I am attempting to "winch" (air ...
73 views

### Is it possible to build a radar that is shielded behind one meter of ceramic material and still detect people 500 meters away?

I saw that there are radars which can detect people behind walls, so I wonder what the limitations of radars are when it comes to detecting people while being protected behind thick ceramic shield.
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### What substances have the lowest dielectric strength (volts/meter)?

All the tables of dielectric strength I can find are lists of materials that engineers use as practical insulators, and air is usually the least insulating thing on the list. Where can I find a more ...
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40 views

### What will happen if you attach the negative pole of welder to the rotor of the motor or the body , will that cause problem?

I have built a machine that rotates a cylinder to weld it, I have to attache a negative pole to the cylinder which is connected directly to the rotor of motor, the motor is controled by an Abb vfd ...
52 views

### Truncation operator

I'm currently working on this question, and I'm unsure how to determine if it is time-invariant or not. When I perform y(t-t0), does it shift even the time at which the step is defined? Furthermore, ...
41 views

### 69kV insulator identification

Rather Specific question, is there a way or could anyone figure out what this clamp-top 69kV multipart insulator came from like who makes it or the technical name etc these are transmission lines in ...
32 views

### Using Relay and contactless water level sensor to switch on or off motor pump

I have no prior experience related to electrical projects and I am having confusion about which type of relay and how to connect relay, contactless water level sensor and motor pump. So basically I ...
67 views

### Principle of RF MEMS switches

I am studying mechanical engineering at university and am trying to design an RF MEMS switch. In "RF MEMS Switch Li-Feng Wang, Qing-An Huang, and Lei Han" says "When an adequate voltage ...
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### Electrical Charges

I have been doing some research on different textile materials and electrical charges. If I wanted to change a negatively charged material to a positive one, would that be possible? Thinking I could ...
216 views

### Why aren't Dielectric Elastomer artificial muscle actuated robots more common?

Well, while searching for dielectric elastomer actuators I can find that they normally have efficiencies around 80% or more (source page 38), they are cheap and easy to build. But the more I search ...
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