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Questions tagged [speed]

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

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1answer
55 views

How does a DC brushless drill-driver work? [on hold]

My new cordless, brushless drill has good torque, but it won't turn below about 50 rpm. My older brush-type drill, same model, will drive screws even at near-zero speed. Does the brushless circuit ...
0
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1answer
31 views

Shunt DC motor controller improvement

A 1.4 A shunt DC motor, with brushes, in a home made pottery wheel from 1970s runs slightly erratically. In general I am well impressed with it as the motor choice is appropriate for the ...
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3answers
50 views

Speed Current Relationship in İnduction Motors

It is said that speed of an induction motor depends on its frequency and torque depends on current. But I will explain what i cant understand here. Let’s think an induction motor runs with constant ...
0
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2answers
41 views

BLDC Motor max load

Hi i have a BLDC moter https://www.banggood.com/350W-48V-DC-Brushless-Motor-Geared-Ebike-Tricycle-Kit-Engine-Electric-Scooter-p-1419702.html?akmClientCountry=NL&rmmds=cart_middle_products&...
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0answers
46 views

ZCD with PIC 18LF45K40

I want to implement phase angle control for a single phase ac fan. To achieve that we need a ZCD circuit interfaced with a microcontroller to get a pulse at zero crossing. As our circuit has some ...
0
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0answers
29 views

How to read Torque-Power diagram for an asynchronous motor

I'm sorry if my question is too stupid, but I am not able to correctly understand how to compare the information showed by the torque-power diagram with the motor test data for a 2000W Asynchronous ...
1
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3answers
96 views

why speed is not directly proportional to torque in dc machine?

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. As per me "in case of dc machine we see that the armature ...
0
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1answer
103 views

Fan speed control with resistor

Electrician from Australia here. Just having an issue with a heater fan in a bathroom for a client. According to the diagram I have posted, I can wire a second fan up to this and it should all work. ...
22
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3answers
5k views

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 ...
0
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1answer
41 views

Sensorless speed control and startup of BLDC

Regarding the sensorless speed control of a BLDC, I have some doubt about what may happen in two scenarios when the rotor's position is unknown: 1) the start-up from zero and 2) with an initial ...
0
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1answer
57 views

DC Series Motor Starting Direction

I have a 12V DC Series Motor - a car starting motor - for an experimental aircraft to pre-spin helecopter-type blades before takeoff. Usually, it works correctly but occasionally with power on, no ...
0
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2answers
120 views

PC fan speed control

I am making a stir plate out of an old PC fan, variable resistor, and DC power supply from this tutorial. I have two power supply's to choose from, their outputs are: PS1 = 12Vdc, 2A PS2 = 12Vdc, ...
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4answers
113 views

Can I calculate how much time it will take for an electrical signal to propagate through a TTL circuit?

Given a particular circuit of TTL, can I calculate how much time it will take for an electrical signal to propagate through some section, or all of, the circuit? If I wanted to know how long it ...
0
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0answers
54 views

DC motor speed calibration

I have seen some treadmills with DC motors that have an option in the console to calibrate the speed sensor by making the motor run from 0 to max speed. Also, some of them have an external ...
0
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4answers
92 views

Could we theoretically massively increase number of parallel computations (for some problems) by getting rid of cpu clocking?

CPU clocking involves making sure that each operation or part of an operation takes exactly a certain amount of time (the machine cycle time). One way to increase the efficiency of a cpu is by ...
2
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2answers
84 views

How does transistor bandwidth affect stability?

I was watching a video where Dave Jones of EEVBlog interviews Rod Elliot of Elliot Sound Products. Rod was discussing that he tends not to use digital chips in his designs because the chip will become ...
2
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0answers
74 views

BLDC motor poles versus Torque and RPM

How to calculate the cost of a BLDC motor? Assume I need 24 stator coils of height 10 mm and width 5 mm. Is there any formula for torque comparison with increasing the number of poles?
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2answers
467 views

How does a hall effect wheel speed sensor work?

I have been researching how a wheel or crank speed sensor works in vehicles and am having a hard time finding a hard truth. I think I understand how it works simply. That the sensor detects a change ...
0
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2answers
77 views

74AS TTL to CMOS pull up resistor and maximum speed (or lowest delay)

Hello I have to pilot a CMOS input 5V chip device with a 7474 flip flop with the lowest possible delay to minimize clock jitter. Signal is about 11.3 Mhz I have two options: 1) 74HC74 (CMOS ...
5
votes
3answers
1k views

How is air conditioner room unit fan motor controlled?

I have a custom project where I need to control fan speed with Raspberry Pi according to data it gets from various sensors. At first I need to know what my motor needs. For fans I use old air ...
0
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1answer
89 views

Methods of measuring speed of anemometer

I enjoy DIY, but to keep things simple I purchased an anemometer cupset (3 cups). I feel that a magnetic reed switch would get "bounce" at higher speeds and I was thinking of a disk with a slot, and ...
2
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1answer
89 views

Simple analog circuit to simulate acceleration and braking behaviour in scale models

Background Scale-model road systems such as Faller https://www.faller.de utilise vehicles that follow a ferromagnetic wire embedded in the road surface. The vehicles operate at full speed and continue ...
0
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1answer
586 views

Measuring speed with Input Capture Mode [STM32 & CubeMx]

I have the L432KC Nucleo. I'm trying to measure low speeds with a 1 PPR (pulse per revolution) sensor. For low PPRs, using the Period Measurement Method is suggested. If I get the period of the signal,...
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0answers
59 views

Boosting speed of data on GPIO line between microcontrollers

I made a circuit in which the data bus P0 of an AT89S52 is connected to the P1 of an AT89C4051 and both clocks are each driven by their own 22.1184Mhz crystal. I have used a 10K standard pull-up on ...
0
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1answer
71 views

Sensor range and speed based on resistor

I have 4 of these sensor circuits and can't quite figure out the optimal resistor value to use. Here's what I assume (which somewhere I may be wrong): The datasheet for the IC states leakage current ...
0
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2answers
80 views

Linearization of motor's thrust

I'm working with a water vehicle that use four motors to move. They are placed at the corner and are fixed. Hence the movements are obtained changing the speed of each one. The vehicle can move along ...
7
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4answers
604 views

Exotic semiconductors for fast digital ASIC

I am researching exotic semiconductors for a digital ASIC with a few million logic gates which should run as fast as possible within a $30 million budget. (Specifically, I need to do a single fully-...
0
votes
1answer
59 views

how to minimize output resistance

I want to setting up a micro coreless motor (5*20 size) for quadcopter. I use BD139 transistor, PWM from STM32 (31kHz PWM frequency) and 500mA li-polymer battery for this work, but the maximum speed ...
0
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2answers
376 views

Is a 'timeout' of 0.2 ms for UART communication realistic?

In most examples (from Arduino/STM32/whatever) I see timeouts of 10 to 100 ms for different kind of communication. However, I am wondering how much 'overhead' there is. Assuming I want to send 8 ...
0
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1answer
38 views

Speed Controller Terminal/Connector?

I'm kind of confused on what connector (labelled B+, M and B-) this is below: (http://kellycontroller.com/kdz4840024v-48v400aseriespm-p-955.html) This is a 48V speed controller designed for up to ...
0
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4answers
270 views

Induction Motor Torque Slip Characteristics

This question was asked in a interview for Scientist position. For a given T-slip characteristics of an induction motor, I want the same maximum torque but at a lower slip value? Is it even possible?...
0
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0answers
67 views

Stepper calculations and motor speed

I did some basic stepper motor calculations and could anyone please let me know if this is right? For the belt driven systems the max motor speed seems very high (lower bottom corner of the image). ...
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1answer
247 views

stepper motor constant speed under load?

Before posting this question I've been looking up google but can't find an answer to this question other than "speed control and torque control". I've done a lot of research on steppers but still don'...
0
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1answer
76 views

Speed of a mosfet triggered directly from the logic pin of an Attiny85?

I have a an N-Channel Mosfet soldered to an adapter board and connected to PB4 of an ATtiny85 via a solderless breadboard. The mosfet currently switches the ground leg of some other low power ...
0
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4answers
437 views

Speed calculation using Accelerometer

I am using ST manufacture Accelerometer(LIS2DE12) and i making a small hobbyist project for me. For this I am using ST-Microcontroller and developing the C code i am using KEIL V5 IDE. Configured the ...
0
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1answer
104 views

efficiency and speed in image processing with FPGA

Hi I have been writing a code in VHDL for some image processing. However, due to some reasons I have not yet determined the sythesis does not stop. I suspect that efficiency of the code is not as much ...
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1answer
73 views

speeding up vivado 2017.2

Hi I am using vivado 2017.2 and it takes infinite amount of time for sythesis and even I suspect that vivado is stuck because I get nowhere. How can I speed the process up? What settings can I change ...
0
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1answer
77 views

How to get data sent to a LED strip each 400 ns?

I want to send data to a LED strip. This has to be done roughly every 400 (or 800 ns), depending on the data (a 0 or 1 to be sent). unsigned long counter = 0; ...
0
votes
1answer
47 views

Mechanisim or Circuit to detect angular position of rotating knob of Motor

I am trying to customize the normal AC motor in such a way that when it will be connected to computer by using some micro controller (e.g Arduino) its rotation will be calculated. i can measure the ...
1
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0answers
67 views

AC voltage through a capacitor

I've built a band pass filter to detect speed using a radar motion detector (IPM-165 http://nic.ath.cx/PDF/sensors/radar/CDM324-doppler/InnoSenT/InnoSenT_application_note_III_11_06.pdf). Using PSpice ...
3
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2answers
687 views

What is the main reason for using speed feedback in a motor positioning control system?

This question is not to solve a particular problem but rather one of principle to understand the main reason a designer would want to include speed feedback in a motor controlled positioning system. ...
0
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1answer
761 views

Calculate speed from encoder counts

I'm using the Arduino Encoder library to keep track of my motor's encoder counts. I need to calculate the motor's speed so it can be compared to a target speed and subjected to PID. I've thought of ...
0
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2answers
94 views

Optimal sensor for measuring object velocity in an open area?

I am trying to measure vertical and horizontal speed of an object attached to a parachute. It will be launched from a low altitude and in an open area, allowing satellite GPS lock. Data treatment ...
2
votes
1answer
46 views

Increasing flash rate of xenon flasher

I've come into possession of a bunch of xenon flasher units of the type commonly mounted to burglar alarms and electric gates. I'm aiming to turn them into tiny strobes as part of a project I'm ...
0
votes
1answer
1k views

Why does speed of DC motor increase when flux is reduced?

I understand that from KVL e = v -IaRa e=k(flux)speed speed=(constant)*(V-IaRa)/flux But physically what causes the speed to increase? What force causes the rotor to accelerate? In fact, ...
0
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2answers
299 views

Relay Specification regarding switching speed

Newbie here, just wanted to ask some clarification regarding reading datasheet since i don't quite find a standard way to determine switching speed. I already had surf and the closest one was the ...
0
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1answer
151 views

Convert 0-5 V input signal to 0-100% PWM

I am attempting to speed control two aftermarket DC brushed fuel pumps in an automobile. The OEM pump control works in the following manner: When driving conditions demand a decrease in fuel supply, ...
0
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1answer
281 views

DDR3 memory transfer rate

I am trying to understand memory transfer rate while working with DDR3. I am getting different numbers. For example, in Wikipedia https://en.wikipedia.org/wiki/DDR3_SDRAM DRAM has peak transfer rate ...
1
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2answers
72 views

Detect black/white at 150 mm

I'm facing a weird request. I have to build a sort of "encoder", to detect the direction and the rotation speed of a black/white wheel at 150 mm from my PCB. In the past I did a lot of this things ...
0
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1answer
89 views

Is this machine code insufficient to chip timing?

I'm having trouble performing basic communication between two IC's. and AT89S52 and an AT89C4051. Both are connected using 6 GPIO pins of which 4 of them on each microcontroller are high nibbles of ...