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

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running time for an e bike on a fully charged battery

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
116 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 ...
2
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1answer
82 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 ...
-2
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1answer
109 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 ...
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5answers
733 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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4answers
416 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
191 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 ...
4
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4answers
228 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
274 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 ...
2
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2answers
577 views

I need help designing a speed control dc motor circuit

We were asked to design a motor speed control circuit using A 15V Source -> Potentiometer ->LPF-> Op-Amp -> ADC ->DAC ->Op-Amp-> Motor Driver -> 3V DC Motor (because of its low cost) I am going to ...
3
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1answer
299 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
167 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
70 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
62 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
293 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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0answers
218 views

Raspberry Pi SPI and AtMega

I'm trying to make multiple DMX modules that communicate with a raspberry pi through SPI, I would assume SPI would be the fastest ? The modules are made of an atmega (not sure which, but probably ...
4
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2answers
289 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
872 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 ...
2
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1answer
88 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
421 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
490 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
390 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
201 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
283 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 ...
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1answer
4k 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
560 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
694 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 ...
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3answers
571 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
4k 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 ...
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1answer
1k 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 ...
5
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1answer
314 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
656 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
19k 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 ...
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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 ...
3
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3answers
2k views

i'm trying to make a small blower motor variable speed but can't

I have a small blower motor 120 v, 1.87 amps, and I want to make it variable speed. I hooked up a dimmer switch for a light bulb but it did not work very well. I went to a electronics store and they ...
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2answers
144 views

What gives some flash memory a higher speed rating than other flash memory?

What gives some SD/MMC cards a much higher speed class rating than other SD/MMC cards? Why are some solid-state "disks" (SSDs) much faster than other SSDs? I'm hoping that I can take at least some ...
3
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2answers
3k views

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 ...
5
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1answer
1k views

How to calculate signal propagation speed through vias?

There is a need to have a group of signals arrive simultaneously to their respective destinations, given that they start their journey at the same time. However, due to physical constraints it is not ...
5
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2answers
806 views

How do I modify a DC electric generator to get the same power at a lower speed?

This will be a theoretical question. Suppose that I have a DC generator, and I'm getting 300VA power from it when it rotates at 2000rpm. I want to make it run at a lower speed of about 700rpm, and I ...
4
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1answer
477 views

Important characteristics of high speed diodes

I am wondering if an application requires high speed diodes, what charactristic I should look for in datasheets? For example, between 1N4448 and 1N914 and 1N3595 who is the winner? My guess will be ...
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2answers
907 views

How to design DC Motor speed control, using PID

I am looking to control the speed of a DC Motor using PID, it is speed control. I understand how the PID works, but i have a few questions. Like,how would I find my gains for each of the PID, what ...
2
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3answers
487 views

Motor controller software design

I have to design a PID controller for a differential drive robot. The hardware board consists of a AVR atmega168 running at 16mhz. Driven by two 24v scooter motors with 256 CPR encoders The motors ...
5
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2answers
3k views

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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4answers
783 views

Different Adder Implementations

I'm putting together an ALU, that I want to synthesize on an FPGA. The carry-look-ahead adder is the one many choose to use as opposed to the ripple-carry adder. However, a thought crossed my mind. ...
4
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2answers
248 views

How to get 3D speed vectors?

I want to make a device that measures absolute small scale 3D speed. Small scale as in 10-150cm movements, and absolute as relative to ground and not relative to the device (the device will turn, ...
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6answers
2k views

Rotary encoders to ensure 2 wheel robot goes straight!

I have successfully counted the rotary encoders on the wheel of my robot so this is not a problem. My problem is what to do with this number. Basically, the bigger problem is that I need my robot to ...
7
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2answers
912 views

What determines the speed of a homopolar motor?

What determines the speed of rotation of a homopolar motor?
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1answer
565 views

angle calculations

I am using a Freescale 3 axis accelerometer to build a model that flies and would like to log and calculate angles during a flight. My model can both hover and move up to 40kph as well as rotate on ...
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2answers
1k views

What is used to control AC motor speed?

This is a AC 220v 60W 0.2A fan I recently bought to replace my old bathroom vent that gave up some time ago. The problem is that the new one doesn't come with a built in speed controller like the old ...
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2answers
361 views

Slowing down a motor - Mousebot

I put together the a Herbie the Mousebot the other day and he is FAST! Too fast to demonstrate in a small area. Have a look a this video to see just how he zips around. Documentation: Mousebot So ...