I have used geared motor,servo motors in my projects but i really want to know what are stepper motors how are they different from other motors
what is:
1.Unipolar stepper motor
2.bipolar stepper motor
what is their power requirements
In short
In short stepper motors are high precision motors that are able to turn in small steps. Usually found in printers, routers, cnc machines etc.
Start here
Here is a nice explination of stepper motors with some animation that should answer some of your questions.
http://www.pcbheaven.com/wikipages/How_Stepper_Motors_Work/?p=0
After reading this you may wish to visit google or youtube and search for a stepper motor tutorial. There is a plethora of information that has already been written and is available on the web concerning this topic.
Enjoy!
Wikipedia is probably a good place to start
http://en.wikipedia.org/wiki/Stepper_motor may be a good place to start. It even describes how bipolar steppers require an H-bridge for bidirectional use (unipolars aren’t). It also shows phase current driving waveforms which may help explain how to create a driver for them.
Cheers