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# Questions tagged [motor]

An electrical actuator that converts electrical energy into rotational motion or sustained linear motion (linear motor). There are many types of electric motors. If the specific type of motor is known, it is helpful to use or add a more specific tag, such as dc-motor, brushless-dc motor or induction-motor.

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2k views

### H-Bridge freewheeling current

I'm building an H-Bridge to drive some motors I have around. I'd like to have a bridge that can be powered by different power sources, for example batteries or atx power supplies interchangeably. I'...
33k views

### Measuring the Internal Resistance of a Brushed DC Motor for Use in Speed Control (IR Compensation)

Is measuring the internal resistance of a brushed DC motor with a multimeter the correct way of doing it? The resistance seems to vary while the motor is being turned by hand; however, the resistance ...
3k views

### Backdriven stepper motor “powering” rest of the board

I have a stepper motor powered by a breakout board that uses the A4983 stepper motor driver (http://www.sparkfun.com/products/10735). Sometimes when the power is disconnected and the drive wheels are ...
14k views

### Understanding how much power a stepper motor draws

I had a previous question describing a power management system where I was trying to power 7 stepper motors from a wall outlet (with switching power supplies and motor drivers). I realized during this ...
534 views

### How to estimate the settling time of the rotor of a stepper motor?

I'm trying to estimate how long I need my stepper's pulses to be to ensure I don't miss steps and assess how big the vibrations will be because of the ringing (i.e. how fast it can be, considering a ...
12k views

### What's the easy way to measure a DC hobby motor's inductance?

When using simulations(SPICE), I need to model a DC motor or an electromagnet, relay ect. as an RL in series. I can measure the R resistance by an ohmmeter. But I couldn't find an easy way to find ...
3k views

### Sensing BLDC motor torque using a current sensor

As it is commonly known, the torque supplied by a motor is directly proportional to the current it draws. So when a motor is under heavy load, the torque required will be more hence it would draw more ...
1k views

### Which informations do I need to calculate the efficiency and horsepower of a 3 phase induction motor?

As far as I know the magnetic force is responsible for the motor rotation. So, horsepower of the motor is mostly related to magnetic flux on the coils (windings). Also magnetic flux is directly ...
1k views

### Refrigeration compressor circuit, help trying to reverse engineer it

I have disassembled the motor controlling circuit for my refrigerator. I am trying to understand how it works, so I hopefully reduce the start surge-current and make it work with my 1000w inverter. ...
297 views

### Novice question about high and low speed motors

Why some low speed electrical drives employ a high-speed motor and some form of mechanical speed reduction rather than direct drive motor. Is it because of size?
912 views

### Galvanic separation between a microcontroller and a motor driver

Is it possible to achieve galvanic separation between a microcontroller and this driver . It's a dual full bridge driver and I'm going to parallel it's outputs (consequently the inputs and the sense ...
2k views

### What sort of electric “motor” would I need to launch a puck?

As the title suggests I am looking at making a hockey puck launcher so I can do some off ice technique training as a goal tender. I have no one to train with so I wanted to create a puck launcher ...
2k views

### Powering a Servo: Do I need a separate power source?

I have a project that utilizes two strong digital, coreless servo motors. Whenever I use DC motors, I usually need to have separate power sources for both the microcontroller and the motors (due to ...
10k views

### What calculations determine the choice of the overload relay trip class to protect a motor

I know that the motor trip current determines the choice of the trip class, but I do not know what are the range values for each one. Lets say that I have an engine with a trip current of 190. Somehow ...
14k views

### What is the relation between the stator current and motor rpm for an AC motor?

A 3 phase AC motor is rated values are: 970 rpm, 50Hz, 380V delta 47A. A VFD drives this motor for obtaining a constant wind-speed which rpm is proportional. The thing is when 885 rpm the stator ...
5k views

### voltage, current, torque and speed in DC motors

First off, please don't accuse me of not doing proper research before asking--I have done much research, but I could not find any answers that made sense to me. I have been playing with some DC motors,...
129 views

### how to calculate the electric power required to rotate an object from 500 gram

I want pull an object (like a rabbit) over grass for teaching my dessert buzzard to catch the object. I made a machine to pull the object about a 50 meters. I can control machine with a remote ...
20k views

### When load increases in rotor of induction motor how does stator draws more current?

When load is increased in the rotor , why does the stator draws more current since the rotor is short circuited. How does mechanical load increases the electrical current flow....
465 views

### dc brushless motor specs for generator

Hello i have done my research and have found varying information relating to the speed at which you must drive a motor to get a desired output and that it is dependent upon back EMF however i am very ...
74k views

### Why are the letters U, V and W used in AC motors to represent the windings?

I am connecting up an AC motor and was wondering if this labeling system was representative of something? Or just another set of letter like X,Y,Z? I could not find any information regarding this in ...
4k views

### In a brushed DC motor, why do the brushes have springs?

In trying to understand brushed DC motors, this post has been very helpful but I still have some fundamental questions about the brush mechanism. For instance, what is the purpose of the spring? (...
122k views

### What is the purpose of carbon brushes in an electric motor

I just took apart our washing machine to replace the carbon brushes. Was wondering why the machine stopped working when the brushes were worn down? Also if the engine makes a wuring noise after you ...
5k views

### How to re-magnetize a permenent magnet motor of small size (model railroad)?

I have several small DC motors where if I place an extra magnet to back-up the included magnet, the performance seems to improve significantly. These motors are 30-40 years old & their ...
3k views

### Braking with an electric motor

I realize that when you short the terminals of a motor, it stops the motor faster than just turning off the voltage. I was wondering if putting a large diode across the leads so that when the motor ...
1k views

### Overclocking my toothbrush

I use these toothbrushes: http://www.amazon.com/Oral-B-Advanced-Toothbrush-Vibrating-Bristles/dp/B00336EUV8 They tend to run out of battery quite quickly. I'm happy to keep buying more because ...
5k views

### Can I use a DC SSR that is switched by a PID controller to control the speed of a 12 V DC fan?

This is my first post here. Let me start by saying that I do not have an engineering background. I tinker with electronics in my spare time (Arduino, solid state low-power guitar amps, etc.), but I do ...
5k views

### How to interpret diode-mode readings from a multimeter

I'm using this multimeter to examine a heat gun fan. The fan has four contacts placed in a circle (well in a square inside a circle). Two opposite each other are labeled ...
1k views

### Arduino Speed Controllers for RC Cars

This may be a lame question but, Speed controllers on big RC cars can they be controlled from Arduino? If yes, do they have a standart? do I control them using PWM values? What should i look for if I ...
7k views

### DIY small motor that turns for x seconds every y seconds

I'm a civil engineer, hiker, and hobby photographer. I am trying to build a little device that gently turns a small motor on every x seconds, keep it on for y seconds, and stop it for z seconds. For ...
1k views

### Braking a DC Motor

I've been working on a lab for my electrical class, and I can't quite seem to find the answer. I have a DC motor that plugs into a 120V supply,from the supply it is connected to the shunt field, then ...
3k views

### Reversing direction of a 115v ac motor using Arduino

I have a 115V brushed motor that I am controlling via Arduino. The manufacturer says it draws 1A but I'm not sure if that accounts for the initial current draw to turn it on. I've had great ease and ...
4k views

### Stepper motor phase

I have a question related to stepper motors. What does the "phase" of a stepper motor mean? I mean when we say that a stepper motor is a 2 phase stepper motor or a 4 phase stepper motor, what does it ...
1k views

### Best most efficient motor type to be used as a DC generator

I'm trying to design a system that requires a very light weight very efficient generator to be used from converting rotational motion into DC voltage(for say charging batteries) As far as I know BLDC'...
2k views

### DC motor causing noise on the power line

I've been building a circuit where I'm controlling a motor using a bluetooth module + phone. I've been having some problems, which mostly are fixed (see topic: previous topic). The main problem I'm ...
6k views

### Recommend motor type to turn baby rocker, into auto-rocker

Would like to convert a baby bouncer (like this one), which requires continuous manual effort to rock it, into one that use electro-mechanical means to auto-bounce. However, my aim is to make these on ...
736 views

### What does the output current rating from an H-Bridge's datasheet really mean?

I bought the H-Bridge VNH7070BAS from ST because it would drive up to 15A, but when I test it, it only reaches 6A and then it shuts down. What does that value really mean? How can I get the output ...
3k views

### How to protect a P-channel MOSFET when driving a motor?

I want to switch a 12 V DC automotive fuel pump in a bench test rig using a P-channel MOSFET, as follows: simulate this circuit – Schematic created using CircuitLab This is a simple on/off ...
1k views

### how to add a motor to a potentiometer?

I have an old piece of analog gear from the 70s and I want to motorize the variable resistors on its panel. I don't want to replace the existing pots with motorized ones but rather to add a motor to ...
405 views

### L6203 H bridge (very) high Rds on

datasheet: L6203 DMOS FULL BRIDGE DRIVER I was testing this H bridge on wire wound high power resistors. I have noticed a high drop in the output voltage. The measurements taken are as follow: Vin=...
533 views

### Sizing a motor for a conveyor

There is a plethora of information on motor sizing on the internet discussing the rated voltage, current, torque and power of the motor, and how these parameters should be selected based on the load ...
1k views

### Relay control of AC motors, handling turn-off kickback

I've been researching how to control a smallish AC-motor using a relay, and more specifically, how to turn an AC motor off using a relay. This is a subject that has been up many times at this site, ...
2k views

### resistive braking for induction motor?

It occurred to me that since single-phase AC induction motors can act as generators, it might be possible to brake an induction motor with a resistive load. The basic idea is that when you want to ...
2k views

### How does the power usage and voltage of a universal motor change when running on DC?

I have a 2400w universal motor from an AC powered garden blower (230V @50Hz here in Australia) and am wondering what voltage and power requirements it would require from a DC source to give roughly ...
6k views

### AC motor Low RPM problem

I'm working on a controller for ac induction motor and it's spec is given below. I could control the speed without any trouble at higher speeds like 2000 rpm and above. I'm using TRIAC phase angle ...
2k views

### How to use a salvaged brushless motor

I recently took apart an HP LaserJet 1320 laser printer to salvage parts from it. Along with 3 solenoids, a fan, lots of gears, 83 springs, and 71 feet of wire, I got a large brushless DC motor with ...
2k views

### Can you use reverse as regenerative braking in a 2 quadrant motor?

I'm having trouble understanding 4 quadrant versus 2 quadrant drive for a 3 phase permanent magnet brush-less motor. Let's say you are riding a scooter with such a motor at a certain velocity forward ...
4k views

### How to tell if brushless DC motor is wired delta or Y?

I have a brushless DC motor I'm working with, do not have any spec. sheets for it. How can I determine if it's wired in delta or Y formation? There is nothing on the label that indicates this. Here'...
433 views

### Can I drive a three phase induction motor with this method?

I have an idea to drive induction motors in a new way. I call it Variable Torque Drive (VTD). You are all familiar with VFD which utilize variable frequency and try to keep the torque constant. This ...