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Servos and Steppers and Gears! Oh my!
Some of our favorite hobbyist electronics utilize motors to mobilize, making them fun and awesome! Including a motor in your project could be challenging, especially if you have never worked with them before.
The following Instructable will explain how motors work, and break down some of the most commonly used kinds of motors.
Some of our favorite hobbyist electronics utilize motors to mobilize, making them fun and awesome! Including a motor in your project could be challenging, especially if you have never worked with them before.
The following Instructable will explain how motors work, and break down some of the most commonly used kinds of motors.
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Signing UpStep 1The Fundamentals
Before we can really begin addressing how a motor works, lets focus on what a motor does. A motor uses electromagnetism to create motion, converting electrical energy into mechanical energy.
Magnetic fields produce physical force that can move things. Every magnet has a magnetic field with a north pole and a south pole. If you try to push the north poles of two magnets together, they will repel each other. The same thing happens if you try to push two south poles together. If two poles are the same, they will repel each other. If, however, you play with two magnets and bring the north pole of one close to the south pole of another, they will attract each other and stick strongly together, opposite magnetic poles attract each-other.
An electric motor uses the attraction and repelling properties of magnets to create motion. There are two magnets in a standard electric motor: a permanent magnet, and a temporary magnet. The temporary magnet is a special kind of magnet, called an electromagnet. An electromagnet is created by passing an electric current through a wire. The permanent magnet has a magnetic field (a north pole and a south pole) all the time, but the electromagnet only has a magnetic field when there is a current flowing through the wire. The strength of the wire's electromagnetic magnetic field can be intensified by increasing the current through the wire, or by forming the wire into multiple loops.
In an electric motor, the electromagnet is placed on an axle so it can spin freely inside the magnetic field of a permanent magnet. When an electric current is passed through the wire, the resulting temporary electromagnetic field interacts with the static permanent magnet, and attractive and repelling forces are created. This excitation of the wire, or electromagnet, propel it to spin on its axle, and an electric motor is born.
Motors are classified by having the following properties:
Magnetic fields produce physical force that can move things. Every magnet has a magnetic field with a north pole and a south pole. If you try to push the north poles of two magnets together, they will repel each other. The same thing happens if you try to push two south poles together. If two poles are the same, they will repel each other. If, however, you play with two magnets and bring the north pole of one close to the south pole of another, they will attract each other and stick strongly together, opposite magnetic poles attract each-other.
An electric motor uses the attraction and repelling properties of magnets to create motion. There are two magnets in a standard electric motor: a permanent magnet, and a temporary magnet. The temporary magnet is a special kind of magnet, called an electromagnet. An electromagnet is created by passing an electric current through a wire. The permanent magnet has a magnetic field (a north pole and a south pole) all the time, but the electromagnet only has a magnetic field when there is a current flowing through the wire. The strength of the wire's electromagnetic magnetic field can be intensified by increasing the current through the wire, or by forming the wire into multiple loops.
In an electric motor, the electromagnet is placed on an axle so it can spin freely inside the magnetic field of a permanent magnet. When an electric current is passed through the wire, the resulting temporary electromagnetic field interacts with the static permanent magnet, and attractive and repelling forces are created. This excitation of the wire, or electromagnet, propel it to spin on its axle, and an electric motor is born.
Motors are classified by having the following properties:
- There's a permanent magnet (or magnets) around the edge of the motor case that remains static, so it's called the stator of a motor.
- Inside the stator, there is a wire coil, mounted on an axle that spinsaround at high speed - this is called the rotor.
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And do u program arduino with a computer?
if yes - Which language ?
Plzz answer.
----- curious beginner
Arduino is a microcontroller (like a mini, programmable computer)
You program it using the Arduino IDE (the arduino program-writing software)
You can go to Arduinio.cc for a LOT of good information about the Arduino.
It is programmed in C / C++
-Ryan
Timing is everything. :)
The inventor of Mr Salty water chlorinator and the Originater of the First Usuable Chineses Computer Keyboard. In which case please take credit for realising my basic theory with Barry to take the stepper motor to its 1,000 degree. If I remember right that took 6 months and $30,000 to realise, congradulations, Student 6 of 20 pass
History back in the eighties they wanted stepper motors to go beyond 1.5-3 degrees I offered a solution . by oscillating the fields with different wave lengths and forms,1,000 th of one degree was achievable using the same motors..Keep up the good work.
Also I agree with Clemtasm. A constant voltage across an 'ideal' motor will give constant speed with varying load. In real motors the speed drops with higher load due mostly to the resistance of the windings.
In a simple motor model (where you do take winding resistance into account, but do not take reactivity or friction into account,) it's pretty easy to deal with the winding resistance. Speed will just be (Vin - Tout/Ka*r)*Kv. Or if you know V and I, just (Vin - I*r)*Kv.
http://www.arduino.cc/en/Tutorial/StepperUnipolar All the chips needed for driving it along with the software to step through the windings is mentioned on that page
4-wire Steppers are driven by alternating the flow through the coils forward/backward so you have two wires per coil. The 6-wire steppers are designed to have the center set to ground, then you energize the coil you want. The interface can be as simple as a 2N2222 transistor per coil. (Or larger MOSFET if more current is needed.)
a 6-wire stepper can also be driven as a 4-wire by not connecting the center lead and thereby using the entire coil. Again... use a bidirectional motor driver. (H-Bridge) to drive them.
Should be changed to:
"Speed of the motor can be controlled by the amount of voltage applied to the coils from the battery to the commutator."
Voltage is proportional to speed and current is proportional to torque.
My understanding is- A DC motor fed a constant voltage will have a fairly constant speed over a range of loads. A motor fed constant current will produce fairly constant torque over a range of speeds
To make a stepper spin, you have to use a microcontroller to pulse each of its coils in a sequence, as shown in your second picture. If you just hooked up a coil to a battery, the axle will be pulled into alignment with that coil and won't spin.
very good instructable!
The Atmel is designed to only supply about 20mA per pin (0.020 amps)... enough to drive an LED or send a signal to another device. Servo motors are fine... the motor driver is built internally... but DC motors and Stepper motors are raw coils which...
a) Need a high current level. (Between 700mA to 4000mA)
b) Output a return spike when power is removed.
d) Pull more current through the core of the chip than it was designed to take.
e) Often require higher voltages, 12v, 24v, and 36v are common.
Sparkfun makes a suitable module that is completely assembled: http://www.sparkfun.com/products/10267
You can also purchase chips and roll your own if you like.
Here is one example:
http://search.digikey.com/us/en/products/E-L6219/497-1426-5-ND/585947
Another advantage to using a chip is that it supports MICROSTEPPING... so instead of 200 steps per revolution you can get 2000 or so. The chip pulses the coils with PWM (pulse width modulation) to allow for intermediate steps... and many chips will also throttle back the current when the stepper is not moving to help the motor run cooler and longer.
I hope that helps.
Jerry
Thanks,
Philip
An alternative is to sell them on ebay. http://ebay.com