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

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How to measure speed without any mechanical or electrical connection?

I would like to build an as-much-portable device for measuring the speed of a vehicle, to check speedometer accuracy and know the offset if one present. The idea is a cigarette pack sized box one can ...
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1answer
30 views

Speed of Synchronous motor determined by frequency, but how about current?

The speed of a permanent magnet synchronous motor is determined by n = 120f/p where f is frequency, n is speed in rpm and p is number of poles. p is fixed in a motor so changing the frequency ...
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4answers
125 views

Building a PWM circuit to control a 90v DC motor at 20amps. Will this work?

Sharing the load among 4 transistors with ballast resistors -
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1answer
38 views

Throughput and speed of data transmission cables [duplicate]

What are throughput and speed limiting factors in an ethernet or any other type of cable which is used for data transmission?
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1answer
132 views

How to measure speed of a ball

I have small box (10cm x 10cm ) and I need to measure speed of ball (r=2cm) getting inside. I assume there are at least two possible ways. Put a sensor inside the box in point A and second one ...
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1answer
34 views

Alternator shaft speed

I am running an alternator with an electric motor (variable speed), but I do not know the shaft speed. I would like to calculate it from voltage frequency. The rotor of the alternator has 12 poles (6 ...
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1answer
205 views

Difference between nominal speed and idle RPM of a DC generator

I am currently studying for a electrical engineering related exam and came across this problem. What exactly is the difference between the nominal and idle RPM of a DC generator, and which one is ...
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0answers
102 views

How can we compare processing times of two designs implemented on different FPGAs?

How can we compare two different designs that perform same task (e.g. processing a 256x256 image) and both implemented on different FPGAs, in terms of processing time(seconds)? For example one of ...
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1answer
498 views

Reading car speed sensor (SDV)

I've been trying to interface with my car's info screen, called a TID (Triple Information Display), from Opel. From the factory, there are multiple things attached to this screen, one of those a line ...
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1answer
61 views

Car speed sensor to turn on something [closed]

Is there a sensor for the speed of the car that can be programmed to turn on something when a car reaches to a specified speed? If yes, what is it’s name, and whare to find it online?
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1answer
165 views

Synchronous motor base speed calculation

I would like to ask the following question. How can I calculate the base speed of a Synchronous motor for variable speed applications controlled in dq frame? I want to calculate the base speed for ...
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1answer
55 views

General purpose cpu as logic analyser better / worse than dedicated FPGA implementation

This question relates to building a cheap but capable logic analyzer. I had the idea of using an x86 cpu that was running a program that could fit in the fastest cache that would just read data from a ...
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1answer
171 views

BJT pre-biased arrays slower than discrete?

I've got a circuit that works - it's job is to convert a TTL square wave into a +/- 12 volt square wave. simulate this circuit – Schematic created using CircuitLab Note that the ...
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1answer
352 views

Is moving fast will effect WiFi transceiving beavior?

Let's say I'm driving a 2010 Bugatti Veyron 16.4 Super Sport, with speed of 431 km/h = 268 m/h = 119 m/s Now I have a WiFi signal receiver installed on the top of the car and a WiFi transmitter in ...
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1answer
56 views

Ceiling fan speed control

I have heard it said that a ceiling fan with a built in three speed manual switch should be set on the high speed setting when using an electronic speed control. I have not found an answer as to why ...
2
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2answers
2k views

Get current gear from rpm and speed through OBD2

I would like to modify my car with the help of Arduino to display the current gear. I wasn't quite sure where should I post this question as it is a car topic, as well as an electric engineering and ...
3
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2answers
3k views

Difference between torque and speed in dc motor?

I have knowledge about the definitions about both speed as well as of the torque. But I am unable to think dc motors in terms of speed and torque. When the armature of a dc motor rotates , we call it ...
3
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1answer
352 views

BLDC speed/torque control with L6229 or L6235

I'm trying to control 12V 12,000 rpm BLDC motor with 3x120° Hall sensors using ST evaluation board based on L6229 IC. I tried to control motor's speed by feeding PWM to FWD/REV pin as suggested in ...
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5answers
1k views

What components or circuitry exist that can provide extremely high speed, accurate clocks?

I've been curious for awhile now about doing some high speed projects, such as measuring time differences of radio wave reception, and was wondering if there exists components that provide clocks much ...
4
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2answers
727 views

Accelerometer double integration error

I wanted to use an accelerometer or IMU to measure speed and displacement over a period of about 1 minute or 400m. From this answer I found at stackoverflow, the error propagates at a rate of \$t^2\$ ...
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1answer
380 views

What's the best method of measuring displacement and speed without resorting to GPS?

Is it possible to determine the displacement, speed and acceleration of someone while running, by using methods like dead reckoning, sensor fusion or other, and sensors like accelerometers, ...
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0answers
56 views

AC Motor operating region

I've been using an ABB IRB 2400 robotic arm to gain experimental data and write a report based on the data. I found that when I operated it at different speeds for pre-programmed paths, I got a ...
0
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1answer
287 views

Measure the speed of a stationary bike with belt drive

I have a problem with the measurement of the speed of my stationary bike. (also here) Parameters: radius of flywheel is 13cm second wheel is 12cm (0.12m) the sensor is simply a reed switch I'm ...
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1answer
171 views

Electron speed in resistors

What affects the speed of electrons in a resistor? If two resistors are connected in series, they both have the same current ; same amount of electrons passing at a point per second. Then if one ...
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1answer
451 views

Calculate Speedup

What is the overall speedup of a system spending 65% of its time on I/O with a disk upgrade that provides for 50% greater throughput. The formula should be Amdahl's law: overall speedup = 1 / (1 ...
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2answers
362 views

How to run a 6v 4amp motor at slower speeds for long periods of time (2 hrs)?

I am trying to get a project done for Halloween. I am running a 6V 4A motor (from a powerwheels) but need it to run slower. I tried using an adjustable charger and ran it at 3V to slow down the ...
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2answers
84 views

How does the bandwidth have something to do with speed

They are saying that, if the bandwidth of a certain device becomes narrow, then its speed decreases. However, how does the speed has something to do with the bandwidth? If you are saying that the ...
2
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1answer
758 views

Ethernet: Why is the link status “down” when there is a speed mismatch?

For any networking (ethernet) equipment, the link status (layer 1) is down when there is a speed mismatch between two ethernet interfaces (say: one is 10 Mbit and another is 100 Mbit). Is it ...
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2answers
7k views

Slow down stepper motor's speed using stepper driver DRV 8825

I've got a Nema 17, rated at 0.8Amps, stepping angle of 1.8 degrees. The motor looks like this, and has six wires coming out of it: The four wires I've used are the ones labeled below (I was ...
2
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1answer
149 views

Capacitor bank with variable speed motor

I have a set of three pumps (power ~100 kW) with variable speed AC motors and I would like to know the best option(s) to reduce the cost of reactive energy. For instance, would it make sense to ...
0
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1answer
161 views

FTDI communication speed

How can I get very high speed from a FTDI chip? I have tried with FT232RL with UART in 230.4kbps but I want much more than this. Will I need some other different speed?
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7answers
449 views

What type of motor can provide smooth motion at low speed around 0.1 to 1 mm/s

I am building a stage for tissue cutting and the motion of the stage should be very slow and smooth. The speed range is 0.1 to 1 mm/s. I got a stepper linear motor from PI (M230.10s), I test its speed ...
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2answers
394 views

Why long pipelines are preferred over high CPU clock?

Why modern CPU vendors prefers increasing the maximum length of the pipeline over increasing the clock? Accordingly my understanding, increasing either increases the number of gate switches and so ...
3
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1answer
206 views

Speed and Position Control for high-volt Elektro Motor with AVR

Is there anything that one can purchase to control speed and position of a high voltage electro motor? I am quite a bit of a noob at this but I could think of a circuit using photo-sensors or ...
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2answers
4k views

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 ...
24
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10answers
5k views

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 ...
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3answers
984 views

Why is propagation delay of ethernet cables unaffected by cable length?

I did some searching on how propagation delay in ethernet cables is affected by the cable length. The answer seems to be that the delay is negligible until the cable length reaches a kind of threshold ...
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4answers
475 views

What limits the speed at which information is sent/received over a fibre optic line?

I was trying to find an answer everywhere, but all I can find is absorbtion and scattering, which doesn't limit the speed itself, just the quality of the signal.
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3answers
1k views

How to make two motors spin at the same speed?

I am currently using two identical motors to drive a robot. The motors are both controlled using relays but one of the motors is spinning faster than the other. How can I slow down the faster motor ...
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3answers
1k views

RPM counter using 8051 microcontroller

I am building a RPM measurement unit using 8051 micro controller. I want to measure RPM of AC motor. I have connected proximity sensor to get the pulse for each turn. I have connected the proximity ...
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2answers
337 views

running time for an e bike on a fully charged battery [closed]

how much time a battery(48 V 35 Amp hr) can drive an electric cycle(weighing 80 kg) powered by a 150 Watts permanent magnet DC motor at an average speed of 20 km/hr.
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2answers
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Can I use 12V voltage regulator and a variable 0 to 30V DC power supply to control my 12V DC motor speed?

I've got a 12V DC motor with: Output power: 3.4 watts Rated speed : 170 RPM Rated current: 0.9A Currently I have a variable voltage DC power supply which can vary the voltage from the DC power ...
2
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1answer
2k views

Control of 4 pin cpu fan with 3 pin socket and …?

I have a problem with controlling my cpu fan speed since it has a 4 pin connector and the socket on my motherboard is broken (transistor connected to it has burnt). I have it connect at the moment ...
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1answer
193 views

What actually limits the speed of a USB flash drive? [closed]

My system outputs data through USB which is to be stored in a external memory. But it seems that flash drive is not having that much speed like that specified in USB 2.0 protocol. What actually ...
8
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5answers
1k views

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 ...
2
votes
5answers
27k views

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 ...
0
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1answer
358 views

Is the speed of light the upper bound on CPU speed? [closed]

Edit: As this my first question in this site I was a bit confused how to pose the question. Because of the way I had put the question before has made it trouble to understand What is the fastest ...
5
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4answers
2k views

How to decrease solenoid speed?

My project is Speed Control of a solenoid. In this project, stroke is 30 mm and I want to plunger cross 30mm in a few seconds (like 5 seconds). For this purpose I want to control the current of the ...
2
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3answers
2k views

Why do higher frequencies mean higher data rates, and why do we even need frequencies to begin with?

This is regarding wired connections. I have heard that higher frequencies mean higher data rates since there are more cycles per second you can fit more data in per second. That makes sense but I ...
3
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2answers
2k views

I need help designing a speed control dc motor circuit

We were asked to design a motor speed control circuit using the following components: ...