I NEED HELP WITH STEPPER MOTOR~

[George221]

i got few stepper motor from robotshop :   12V 0.68A 125oz-in Unipolar Stepper Motor

(http://www.robotshop.com/ca/rbsoy14-soyo-unipolar-stepper-motor.html)

Question: i wanna control it that it can move both direction, so i tried to use darlington array uln2004A
                but the collector-current rating is 500 mA. will this burn when driving 0.68A stepper.

                is there another darlington array with higher current rating ? or other way to drive this stepper in both directions.
               

[waltr]

You can use discrete MOSFET, Bipolar or Darlington transistor instead of an array. An arry is not needed for bi-directional control of a uni-polar stepper motor.

Try googling 'uni-polar stepper drive' for lots of circuit examples.

[jwatte]

Pretty much all motor drivers these days use MOSFET transistors.

Because your motor is unipolar, you need four transistors. Four N-channel MOSFETs will work just fine, and you can buy power MOSFETs with logic-level I/O for about $1 each from places like Digi-Key. Adafruit also sells them.

You could also get a dedicated unipolar motor driver circuit, but I don't think you'd get anything out of that that you wont' get out of just discrete MOSFETs.