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arshia
what do u mean by constant current driver??? i am using mosfet and obviously they would be constant current ......
nd resistance per coil is almost 3.9 ohms
No, a mosfet driven as a switch is not a constant current device. This is the sort of thing you need: [www.pololu.com]. There are also many similar devices available on eBay, just search for A4988.
If the resistance per coil is 3.9 ohms, than that motor probably needs about 1A per winding if it is NEMA 17 size.