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

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Latency of DDR RAM operation compared to bandwidth capacity for two memory modules at a given clockspeed

I've wondered this for a while and I need some help conceptualizing it. Why isn't Nanoseconds of latency a good measurement of speed for comparing two different memory modules, both with the same ...
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0answers
33 views

Noiseless electronic ceiling fan speed control

Is it a good idea to control speed of a ceiling fan by letting the TRIAC run in PWM mode as explained? The TRIAC is allowd to pass the current for a complete cycle of the mains and then stopped for a ...
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2answers
64 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 ...
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1answer
46 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
159 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 ...
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0answers
82 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 ...
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1answer
62 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
116 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
95 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
53 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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0answers
36 views

Proper motor for a fan/propeller to be used in a permanently installed sculpture

I am designing a sculpture with some moving parts and one of those parts is a rotating fan or propeller-like vane connected to a motor (it will be a light plastic part of ca. 20-25 cm. of diameter, so ...
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1answer
177 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 ...
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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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2answers
200 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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3answers
322 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
204 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
383 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
83 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
980 views

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 ...
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1answer
681 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
139 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 ...
7
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5answers
878 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 ...
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5answers
4k 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 ...
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1answer
235 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 ...
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4answers
501 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 ...
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3answers
595 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 ...
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2answers
803 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: ...
3
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1answer
583 views

Brushless DC Motor - Sensoreless Startup Algorithm

I am trying to achieve speed control of a sensorless Brushless dc motor (Back Emf method). Initially its speed is zero so Back emf is zero, so there will be no feedback, in that case what do i do? ...
3
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1answer
219 views

Ways to build a speedometer for a bike or skateboard

I'm trying to think of different ways to build a device that will allow me to mount it to any moving object so that the moving object will be able to discern it's speed (It DOES NOT have to be very ...
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1answer
84 views

ATmega1284 running very slowly until reflashed

When I power up my ATmega1284, it executes extremely slowly -- probably less than a tenth of its normal speed, judging by the cycling LEDs it runs. It's configured to use the internal oscillator with ...
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1answer
91 views

Clarification of speed control

Please could I know if the diodes in EESE question “Control speed of Nidec fan” ARE zener diodes (as the symbols sugest) or normal diodes as on another article they had the exactly the same circuit ...
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4answers
334 views

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 ...
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2answers
562 views

Maximum speed of stepper motor

I would like to compute maximum speed (RPM) of my bipolar stepper motor 42BYGHM809 -- rated voltage 2.7 V, rated current 1.78 A, phase resistance 1.6Ohm, phase inductance 2.5 mH. I know how to ...
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4answers
2k views

which RPM measurement method is suitable?

I have a PMDC motor which is electronically controlled for speed. And it is a closed loop system. A proximity sensor is there to measure the speed of the motor and there are 12 bolts attached to the ...
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1answer
102 views

Program speed with and without JTAG debugger

I have some custom boards with an ARM processor (marvell78100, armv5 compliant), some SDRAM and some Flash. I'm trying to investigate timings problem with the SDRAM, since it seems the layout was not ...
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1answer
631 views

Feedback for DC Motor Speed Control using PID

I'm working on a project in which I have to control the speed of a DC motor using an analog PID(using op-amps). The input will be provided with a potentiometer. The issue is that I can't figure out ...
4
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1answer
795 views

AVR assembly: Most fastest way to increment two combined bytes

What could be the fastest way to increment two combined bytes in assembler (assuming I'm working on a 8-bit CPU)? Currently I'm doing this: ...
4
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3answers
672 views

How to syncronize two motors with one pot?

I am trying to synchronize two dc motors with their own controllers. The controllers are name brand and use a 10k pot to control the speed. I have a duel 10k pot and would like to be able to "trim" ...
2
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1answer
241 views

Optiflow based Odometry speed sensing

Am planning to build a odometry speed sensor based on optiflow to measure the speed of the conveyor. I am using ADNS-5020-E from a old mouse of mine and managed to get the X and Y coordinates by ...
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0answers
338 views

high torque and high rpm dc motors

I am making an electric 4x4 car, will it make a difference in overall speed if: Case1: all 4 motors are high torque and relatively low rpm Case2: 2 high torque relatively low rpm and 2 high rpm ...
14
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1answer
6k views

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 ...
2
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1answer
695 views

Why does BLDC Motor Spin Slower with Same Duty Cycle at Higher Frequencies?

I have an OTS BLDC motor controller as well as one that I just made myself and both seem to be dramatically slower at higher frequencies. When I look at how much current is being drawn it makes ...
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4answers
958 views

Can I reduce rpm further of a gear motor by using PWM?

I am working on a project where I need to move the object from one point to another in a dead slow speed , The object doesnt weight more than 5 pounds . I found a DC gear motor with has a RPM of 0.5 ...
14
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3answers
741 views

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 ...
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1answer
6k views

What is the difference between 1-phase and 3-phase motors?

I've read the wiki page on AC motors, but it's still unclear to me as to how they work. I'm looking at motors for a project and need them to be able to have their speed controlled by a light dimmer ...
2
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1answer
2k views

Speed of electricity (signal propagation?) through copper for communications delay

I would like to be be able to calculate the delay for communications data within TCP/IP networking through cat5e networking cable. That is a pretty vague ...
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1answer
384 views

What limits the modulation of digital signals?

I am trying to understand why there are different speed on different frequency bands. I see that e.g. ZigBee can do 250kb/s for both 2.4GHz and 868/915MHz, but ...
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1answer
957 views

How do I calculate necessary mosfet turn on/turn off time?

I'm trying to measure capacitance of C1 using this design: Everything works from 3.3V. The mosfets is my addition to it - i want to discharge the capacitor after each half-cycle. Everything works ...
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4answers
32k views

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. Can anybody please help? Will a 100V ...
3
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4answers
1k views

Conveyor belt speed monitoring

I am new to all this so forgive the dumb rating. I need to monitor the speed of a few conveyor belts, the belts are around 10ft to 50ft long and 3ft wide and has anything from heavy boxes to thin ...