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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.

40
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1answer
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How can I implement regenerative braking of a DC motor?

I know that many electric cars are able to convert the momentum of the car into stored energy in batteries, rather than convert it to useless heat at the brake pads. How does this work? How can I ...
21
votes
3answers
8k views

Why should I worry about a motor causing my supply voltage to shoot up when the back-EMF can't exceed the supply voltage?

I have heard people say that in motor control circuits, one must take precautions to keep the motor from feeding back into the power supply, causing the supply voltage to rise, consequently breaking ...
22
votes
3answers
68k views

How to drive a MOSFET with an optocoupler?

What's the proper schematic for driving this MOSFET from a microcontroller pin through this or this optocoupler? The MOSFET will drive a motor @ 24V, 6A.
19
votes
4answers
26k views

How diodes protect H-bridge DC motor driver?

I don't really understand how these diodes in this circuit and similar circuits (like driving a relay circuit) protects the controller circuit from the energy stored by the inductance of the coil. I ...
15
votes
4answers
1k views

H-Bridge Fly-Back

Sorry if this question is a little long, but I though it prudent here to discuss the state-of-the art as I know it before asking the question. ISSUE When using an H-bridge to drive a bidirectional ...
6
votes
2answers
19k views

Motor driver using only a 2N2222 transistor?

Is it possible to build a motor driver using only a 2N2222 transistor? If yes, then how?
80
votes
10answers
270k views

Why does a Tesla car use an AC motor instead of a DC one?

I was just watching a mega factory video and wondered why they use an AC motor which requires a power inverter instead of DC which may be powered directly from their DC battery? Introducing an ...
29
votes
11answers
17k views

I'd like to learn how to make my own USB gadgets

I've been writing Linux character device drivers for other people's stuff for some time. I'd like to find a new hobby and the thought of making my own USB gizmos seems really neat. I would be ...
24
votes
1answer
23k 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
votes
4answers
9k views

Varying run capacitor for speed control of single phase motor

If I want to vary speed of single phase electric motor within say, 10 to 20 % max of its rated speed (or torque), is it a good idea to change its run capacitor setting? Either via multiple capacitor ...
2
votes
2answers
2k views

Which of the following motors best suit as a wind generator? [closed]

I'm watching some brushless outrunners with low kv as a generator for a simple wind turbine that I'm going to build soon. It might not be a scale or fully useful turbine, because I want to build it ...
30
votes
8answers
230k 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 ...
4
votes
4answers
26k views

Build an H-Bridge Motor Driver with 4 N-Channel MOSFET

I have bought 4 N-Channel MOSFETs to build an H-Bridge Motor Driver. My Motor drive and my power supply voltage is 12v. My TTL logic voltage is 5v as I want to speed up/down the motor with uC PWM. Now ...
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2answers
2k views

15V 3A dc motor PWM frequency setting

What is a suitable frequency for 15V/3A DC motor? Is there any effect on the motor when the frequency is changing? I am confused with this until now and the Internet shows a lot of theory that ...
32
votes
2answers
63k views

Purpose of the diode and capacitor in this motor circuit

I'm hooking up a small DC motor to an arduino using an NPN transistor using the following diagrams I found online: The circuit works, and I'm successfully able to make the motor run. Now, I'm ...
8
votes
3answers
23k 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 ...
17
votes
3answers
45k views

Why is PWM used to control DC motor speed instead of using a variable resistance?

My question is at the end (to change the speed) we are controlling the input voltage of a DC motor in both PWM (pulse width modulation) and variable resistance cases. Is the only reason for choosing ...
11
votes
4answers
15k views

Explanation for Differing Stator Winding Orientations

As a layperson, I'm trying to understand the basic configuration for an induction motor or generator. I've looked at many diagrams and photos/cutaways of stator wiring and I've noticed two different ...
11
votes
3answers
2k views

Capacitors and motors

Every RC car I've cannibalized has had a small ceramic capacitor soldered on to the contacts of the motors. What is the purpose of having this? What happens to the performance of the motor with out ...
6
votes
3answers
5k views

How do I know where I need decoupling capacitors?

I'm building a motor driver shield for the Arduino. Here's the schematics (please forgive the messy layout): And here's the PCB layout: I'm testing it out by breadboarding it while running a simple '...
13
votes
4answers
9k views

How can I sense the motor's current?

I need to drive a DC motor @ 24V, 6A with a MOSFET. How can I sense the current that the motor is drawing with a microcontroller? I have to know when the motor is stalled.
9
votes
1answer
2k views

Ground noise and voltage drop problem

I have an RC device powered by a 3.7V poly battery, which includes a motor and a 40KHz sonar. The voltage across the sonar sensor is amplified and then adc-ed. The motor is driven by a 2KHz PWM. When ...
5
votes
3answers
7k views

Using electric motor to adjust blinds?

So I'm trying to do some insane home DIY with my room blinds. I'm trying to make them adjust (go up and down) automatically. Now for this, obviously, I will need a motor. The blinds I'm working ...
3
votes
1answer
15k views

DC Motor as a Generator Voltage and Current

Is there any way to calculate the expected voltage and current, assuming I am turning it at the specified RPM value, when using a DC motor as a generator without physically testing it? In my case I ...
0
votes
1answer
2k views

Controlling a single phase AC fan with a 0-10V DC input

I have a fan motor which is a permanent split phase single phase capacitor motor: http://uk.rs-online.com/web/p/axial-fans/2781543/ I currently control this fan's speed with the following controller:...
3
votes
3answers
1k views

Why do we want higher power factor in ac motors?

Here is a simplified 3P electric motor below: This motor is simply combined of three coils facing toward to the rotator (in the center) 120 degree apart to each other. The user wants his rotator to ...
2
votes
2answers
2k views

How to prevent DC motor from dropping voltage of supply when switching on

I have a circuit which uses an ATtiny85 output to a transistor (S9013), which will trigger a relay that controls a motor. The reason for the transistor to relay is because I do not have a transistor ...
2
votes
4answers
17k views

How to use timers in STM32 board and HAL library in order to measure speed of motor?

I need to measure the speed of a rotating motor fitted to an encoder disc with 20 slots. The LM393 based sensor is kept at the right place, so that encoder disc rotates in between the sensing part. I ...
1
vote
2answers
7k views

How does a capacitor function in a 120v ac motor circuit?

I dont understand the direction of current flow when a capacitor is wired in series with the start windings in, say, a fridge or ac motor running on der 120v ac. Wiring diagrams seem to suggest ...
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votes
3answers
4k views

How can i make my 380/380 volts motor to run on 220 volts?

I bought a small and old combi woodworking machine "Emco Start". The Machine is running 380v. The problem is that i only have 220 at home. I made some research and i found out that it is possible to ...
19
votes
3answers
29k views

Is it possible to drive a stepper motor greater than 1000 rpm?

How could I achieve this? What are the stepper motor facts and principless that I have to keep in mind to design a circuit to achive this goal? Are there any readymade/open source alternatives and ...
10
votes
5answers
33k views

Braking a DC brushed motor

What would happen if I short the terminals of a DC motor together while power is disconnected but it is still freewheeling? According to several sources, it would brake the motor. This makes sense. ...
15
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3answers
31k views

Control differences between ac induction motor and brushless dc motor?

I have a fairly solid background in industrial AC motor control (soft starters, VFDs, etc.) but something that I'm certainly NOT well versed in is brushless DC motors... the type found in every hard ...
6
votes
4answers
62k views

Understanding motor constants Kt and Kemf for comparing brushless DC motors

So for a practical definition, the torque constant Kt specifies how many Nm of torque you'll get from the motor at a certain current? Is a bigger Kt always better? I am more confused about the ...
9
votes
2answers
10k views

Methods of filtering noise caused by DC brush motors

I am looking for any information that would help me reduce the power rail noise and EMI of DC brush motors. I am building a robot that is powered by 2 x 250 W 24V DC motors. Thank you in advance
16
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2answers
9k views

Why connect capacitors to motor body?

So I've found a motor circuit which looks like this: Since many users here believe that my hand-drawn circuit schematics are in fact pictures of flying spaghetti monster, I'll also provide a written ...
9
votes
3answers
9k views

Why do we need a ramp for stepper motor?

I am a newbie and trying to understand how i can run a stepper motor. The concept i had in mind was that steppers need digital pulses to run, and i tried it out too. I was able to run the stepper i am ...
6
votes
3answers
17k views

How do DC motors work with respect to current, and what consequence is the current through them?

Motors in general have always been a difficult subject that I cannot fully wrap my head around. Considering DC motors, what determines the rate at which the motor spins? It was my understanding that ...
12
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4answers
3k views

Is it valid to consider back-EMF in a DC motor equivalent to increased inductance?

I know that back-EMF can be considered as a voltage source in series with the motor which is proportional to speed. This is the common understanding, and I totally get it. Before I understood this, I ...
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3answers
1k views

Snubber diodes for a DC Motor with 2 relays

simulate this circuit – Schematic created using CircuitLab Description: RLY1 relay switches 12v on or off. RLY2 changes direction of current flow to the motor. I have flyback diodes on RLY1 &...
4
votes
1answer
2k views

MOSFET H-bridge design

given the circuit below to be used as a H-bridge with AVR PWM. Is this a good desing to use? What can you recommend? I already built something like this but without the resistors. ( and so burned ...
4
votes
3answers
10k views

Detecting dry-running of water pump

What are some reasonably reliable ways of detecting that a water pump (electrical motor based) is "dry running", i.e. no water is passing through the pump either because there is no water available at ...
2
votes
1answer
1k views

Using a single phase induction motor equivalent circuit in LTspice

I was planning to simulate a circuit which will control a single phase induction motor in LTspice where mains is 230VAC 50Hz. In my previous question, I failed to find an example: Modelling a "...
0
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4answers
3k views

How do I get a position from an encoder?

I have a motor that drives a rail which I need to know the position of. I have an AM102 encoder attached to the motor. But am unsure how to get a position from it. I have powered it up and attached ...
0
votes
3answers
10k views

PWM vs ESC for speed control for Arduino quadcopter

I'm from a computer programming background, but I'm interested in combining hardware with software, so I'm playing around with Arduino. Currently going through things on things needed to build a ...
0
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3answers
1k views

Why does a DC motor spin when there is no load applied to it?

So this is a characteristic of a DC motor: When armature current=0, apparently it still spins quite fast. From what I know, a magnetic field causes a mechanical force on a conductor only when there ...
6
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2answers
137 views

Do electric motors have the same efficiency when operating as generators?

Its in the title. I'm just curious and it turns out that either this is such a stupid question that no one has bothered to answer it, or i'm just not good at googling today. I guess I'm thinking ...
5
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4answers
2k views

How to mount electronics on a vehicle chassis safely

I want to implement a control system I designed for a light electric motorbike. I would like to mount it as professionally as possible on the chassis. It consists of a power system pcb and a SAMC21 ...
4
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3answers
8k views

Using a motor to open doors

I have made a wooden case to hold both my Xbox 360 and my PS3. It's as wide as both consoles laid down next to each other and as high as the console. it has 2 doors on the front, one for each console. ...
3
votes
3answers
9k views

What is good device for generating vibrations, offset weight motor or solenoid or some other?

I am building a vibrating device for that I am thinking to use a solenoid for vibration. The solenoid will be used such that device will be mounted in the floor and when a stick is put over solenoid, ...