Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [speed]

Speed is a scalar quantity referring to the rate at which an object changes position (but is not position-sensitive).

Speed is a scalar quantity referring to the rate at which something changes position. Because it is not a vector quantity, something that is moving quickly in an oscillating manner (such as the diaphragm of a speaker cone) might be described as having a high speed, but zero velocity.

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How are current and voltage related to torque and speed of a brushless motor?

I know that electric vehicles have different performances depending on battery and motor, but it's not clear how electrical and mechanical units are related. Will a 100V motor raise against slopes better than a 50V motor?
jumpjack
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Why can't Wi-Fi run at 2.4 Gbit/s?

So Wi-Fi runs in the 2.4 GHz band, yeah (and the new ones 5 GHz)? Which means that every second, a Wi-Fi antenna outputs 2.4 billion square wave pulses, right? So I was wondering, why can't it transmit data on every pulse, and be able to send data…
MC ΔT
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Why are relatively simpler devices such as microcontrollers so much slower than CPUs?

Given the same number of pipeline stages and the same manufacturing node (say, 65 nm) and the same voltage, simple devices should run faster than more complicated ones. Also, merging multiple pipeline stages into one should not slow down by a factor…
Michael
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How can I measure back-EMF to infer the speed of a DC motor?

I'm interested in measuring the back-EMF of a motor to determine a motor's speed because it's cheap and requires no additional mechanical parts. How can I measure the back-EMF when I'm driving the motor?
Phil Frost
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What's the maximum CAN bus frame (message) rate at 125 kbit/s?

My CAN bus is running at 125 kbit/s and is using extended frame format exclusively. I would like to know what's the maximum rate of CAN frame I can send out. Suppose the data length is always eight bytes. According to this Wikipedia page, each frame…
Penghe Geng
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Why does RAM (any type) access time decrease so slowly?

This article shows that DDR4 SDRAM has approximately 8x more bandwidth DDR1 SDRAM. But the time from setting the column address to when the data is available has only decreased by 10% (13.5ns). A quick search shows that the access time of the…
Arseniy
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Why is the serial connection faster than the parallel connection?

As a software developer the concept of parallel processing usually meant faster processing because it meant things don't have to wait for the other processes to finish if they don't need to. So how come the serial connection is looked at (arguably)…
M. A. Kishawy
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What is a good approach to detecting distance and speed in model railroads?

Up front I must admit to little hands-on knowledge of modern microcontrollers and their software - I know power engineering and big motors much better (45 years of it). Now, my question: Trying to get grandchildren enthused about electronics. They…
Seemingly So
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Speed of compound wound dc motor

This is homework. Given a 500W, 200V compound wound motor with constant shunt field and a series field that varies with armature current, how do we calculate the change in motor speed. I know the equation for motor speed \$n\$ $$n \propto…
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Determine MOSFET switching speed

How can I determine the switching speed of a MOSFET, with given Qg (gate charge), Vgs (G-S junction voltage) and gate resistor ? How should I determine the required value of the gate resistor?
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AC fan speed control

I use this fan to cool my room, but sometimes it is too fast and I have to frequenctly turn it on and off to keep normal temperature. Maybe it is possible to reduce the speed by connecting a resistor in series or using a variac. The fan uses some…
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Circuit that measures the speed of sound in concrete

I need a circuit to measure the speed of sound in concrete to 1μs or better. This is for a school demonstration where students who study construction will use this circuit to measure the speed of sound in a sample of concrete to determine the…
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Torque relationship to speed in a DC motor

I have a conceptual doubt about torque-speed relation in a DC motors. It's probably a gap in my thinking but I'm posting this question anyway. Torque and speed in a DC motor are said to be inversely proportional. But doesn't an increase in torque…
Vineet Kaushik
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What determines the speed of a homopolar motor?

What determines the speed of rotation of a homopolar motor?
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How to track motion of a moving ovendoor

At work, we are measuring various parameters to test out a newly designed oven prototype. To make things more efficient, I am trying to create an electronic setup to automate the measurement, in particular of the door's motion (from fully open to…
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