An electrical actuator converting electrical energy into rotational motion.

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27
votes
9answers
19k 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 ...
22
votes
6answers
53k views

What is a “digital” motor?

Dyson keep going on about their new "digital" motor. What is a digital motor? How can a motor be digital, it is inherently analog? Is it just marketing doublespeak?
18
votes
11answers
4k 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 ...
18
votes
6answers
29k views

How to drive brushless motor with Arduino?

Is it possible to drive a brushless motor directly with Arduino? Or should I revert on controlling a brushless motor ESC with PWM pulses?
17
votes
6answers
6k views

How do I physically work with a hobby motor?

How do I incorporate a hobby-style motor into a project, physically. How do I mount it and connect a wheel to it? (Assume that I have a working H-bridge or even switches, and am not concerned about ...
16
votes
3answers
2k views

Why don't all motors burn up instantly?

A motor rated for 3S (11.1 V) has an internal resistance of 0.12 ohm. The maximum current is 22 A. 11.1 V / 0.12 ohm = 92.5 A Doesn't this mean ...
16
votes
3answers
1k views

In a DC motor, is there one commutation point that is optimal in all respects?

This recent question got me thinking about commutation timing, and why advancing it can be desirable. However, I wanted to consider more deeply the underlying phenomena, and I'm pretty sure my ...
15
votes
2answers
7k 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 ...
14
votes
3answers
954 views

Why do refrigeration compressors stall when switched off and on quickly?

All of the air conditioners I've worked with have the following words on them: Before restarting, wait three minutes. In the event the air conditioner's compressor is switched off and back on ...
13
votes
7answers
1k views

Why are rectifiers-inverters used to drive AC motors instead of using the rectified current to drive DC motors?

I understand the advantages of using a rectifier-inverter system to drive an AC motor instead of simply plugging it into mains power, as it allows much better control of its speed and performance; but ...
13
votes
1answer
6k views

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 ...
13
votes
2answers
2k views

How is this design for a basic PCB pick and place?

I have zero experience with any serious mechanical design, but out of necessity and curiosity, I'm attempting to build a pick and place machine (for my hobby projects as well as low-volume PCB ...
12
votes
3answers
1k 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 ...
12
votes
3answers
4k views

Arduino Stepper Motor

How do use use an Arduino with a Stepper Motor?
11
votes
4answers
3k 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.
11
votes
1answer
5k 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 ...
10
votes
2answers
4k 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 ...
9
votes
3answers
715 views

shooting object by using a DC motor

This is not directly electrical, but I am working on making a real life version of a coin block from Mario. Basically I use an LDR and to detect if someone punches the block and then use a transistor ...
9
votes
6answers
11k views

Very Slow Electric Motor

A customer has asked: I want to slow down a small hobby sized DC motor to a user variable range that runs from slow to zero RPM. I would simply use a wall wart for a power supply and a ...
9
votes
4answers
512 views

Precise motor positioning

I am trying to make a device that uses several motors all with an arrow fixed on top that has 8 fixed positions (N,NE,E,SE,S,SW,W,NW). I am trying to avoid servos and steppers because of the price, so ...
9
votes
4answers
710 views

Methods to accurately move an object across a 2-D plane

This is the opposite/complement of my previous question, which concerned measuring the precise position of an object as it is moved/drawn by someone over a short duration. Assuming I use one of ...
9
votes
3answers
726 views

Are there any types of DC motors that self-lock themselves?

I have a small DC gear motor which spools a plastic line. Once I've engaged the motor to tighten the line, I want to lock it in place so that the line doesn't unspool. I would then like it to remain ...
9
votes
2answers
3k views

Continuous rotation 'servo' vs DC motor

Under what circumstances should I prefer a continuous rotation 'servo' to a DC motor, or vice versa? It seems to me that to use a DC motor, I'm going to need three pins from an MCU -- two for ...
8
votes
4answers
2k views

Why use DC motors for driving elevators?

This New York Times article says that on November 14, 2007 Consolidated Edison Company was going to end supplying direct current to the remaining several buildings that used those to run elevators. I ...
8
votes
6answers
430 views

Why are battery-powered appliances and tools specified in volts? [closed]

"Powered with a suction of 18 volts" Isn't this just a nonsensical "bigger is better" measure? The thing you really care about as a customer is the motor's torque or power or RPM or something ...
8
votes
3answers
18k 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.
8
votes
2answers
3k views

Difference between Brushless Motor and Stepper Motor

I think I understand the operating principles of a brushless motor and a stepper motor, but I'm a little confused about the difference. Is a brushless DC motor a very basic stepper motor? With ...
8
votes
1answer
260 views

Could I double the batteries for double the usage time?

If I were to double the exact same battery of a particular device (noted below), could/would that effectively ~double the device's usage time (more or less)? For reference -- There's a motorized ...
8
votes
2answers
256 views

Batteries for 12- to 24-V motors

I have some nice gear motors that run on 12 to 24 volts, and want to use them in a medium-sized mobile robot -- maybe 30 cm * 30 cm for the base. I only expect it to run indoors, or possibly outside ...
8
votes
3answers
307 views

Measuring force developed by a robot

I've been playing around with a Lego Mindstorms NXT robot, gearing it for speed and power. To my dismay, when geared for power, it wasn't any harder to stop than when geared for speed -- I suspect ...
8
votes
3answers
1k 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 ...
7
votes
3answers
948 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 ...
7
votes
4answers
5k views

DC Motor control with an Arduino

This might be a simple, silly question, but I am wondering why I can't just connect a DC motor to an arduino board to have it running. One pin to the ground and the other to one of the PWM outputs. I ...
7
votes
5answers
914 views

Synchronise multiple Mega boards to run multiple servo motors

My friend Jules asks: The aim is to get as many servo motor controls as possible - looks like the maximum an Arduino will output is 14? Digital I/O Pins54 (of which 14 provide PWM output) ...
7
votes
4answers
10k views

What is back-emf: counter-electromotive force?

Could someone knowledgeable on the subject explain what exactly is this back emf? How is it caused in a motor/generator, which components and which effects determines it?
7
votes
2answers
2k 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
7
votes
2answers
2k views

BLDC and three phase inverter

I want to run/control a BLDC motor from a DVD/CD-rom player and found a schematic how to do this, the so called three phase inverter (see right schematic on this page: ...
7
votes
5answers
441 views

Good motor supplier?

I'm looking to start a few different projects and stock up on some basic components - I was just wondering if anyone knows a good supplier of DC motors, stepper motors and servos? I'm in vicinity of ...
7
votes
2answers
428 views

Can I get a pair of schottky diodes in a single chip?

I'm building a motor driver circuit, and am looking at diodes to clamp the output voltage between the supply rails. Apparenly, I should use schottky diodes for this purpose. My question is, are there ...
7
votes
2answers
345 views

Driving a small motor: What's needed?

This question is very basic, but I'd like to ask it anyway. I need to drive a small motor. I'm thinking about connecting it directly to 4 AA batteries and using a simple switch. Is there anything ...
7
votes
3answers
9k 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 ...
7
votes
2answers
1k views

What determines the speed of a homopolar motor?

What determines the speed of rotation of a homopolar motor?
7
votes
1answer
429 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 ...
7
votes
4answers
26k 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 ...
7
votes
3answers
7k views

When should I fire the TRIAC's gate when controlling an inductive load (AC motor)?

I'm using a combination of opto-triac + TRIAC to control a 230V AC motor with a microcontroller. For detecting the zero-crossing of the voltage I'm using another optocoupler. I know that the AC ...
7
votes
2answers
1k views

Can Arduino Mega handle 6 motors independently

I wonder if anyone can help me I am modifying an ROV and thinking of using Arduino Mega I am new to electronics and robotics and wonder if the Arduino Mega can control 6 DC motors independently as ...
7
votes
1answer
284 views

Need help understanding and interpreting IGBT datasheets

When it comes to motor control, I understand that we have the option of using discrete MOSFETs or IGBTs. Also, there are some products in the market where 6 IGBTs are placed in one single package, ...
7
votes
1answer
862 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 ...
6
votes
3answers
509 views

What would be the difference in a coil of wire and just a cylinder of solid copper?

Ok so I am learning about induction and I always see coils of wire with no insulator. So I was wondering, What is the significance of it being a coil of wire rather than just a solid cylinder since ...
6
votes
3answers
799 views

Why Have Non-Zero Timing on a BLDC?

I've heard you can go faster in one direction if you adjust the timing, but do not understand why? I have a sensored bldc motor with a 30deg shift of the hall-effect sensors, tried going forward (CCW ...