Choosing a bipolar stepper motor driver ic

Hello everyone, I need to control a few bipolar stepper motors (this http://www.motors.wrobots.com/EM-257_17PM-K212-PIT.php, salvaged from a printer) for an upcoming project.

After looking around for a bit i decided to go with the SN754410 but i realized two things : - on LadyAda's motor controller page they mention the following "the output diodes were designed for ESD protection only and that using them as kickback-protection is a hack and not guaranteed for performance." and they advise using a L293D instead. -ordering the L293Ds i need would be quite a bit more expensive

I am pretty much a complete beginner when it comes to motor drivers, and even after looking at the different specs i am still confused about which one to choose...: as this will be used in a diy CNC machine i would rather not risk burning the electronics out at a point?

Thanks in advance for any advice!

It is easy enough to add normal rectifier diodes for reverse protection like the 1N4001 they are cheap enough.

However, looking at the motor I would be surprised if it had enough power for a CNC project.

There are two types of stepping motor controllers, ones that just act as switches and feedback types that control the current as well. You are better off with the second type because you can then feed the motor with a much higher voltage than is needed to achieve the maximum current. This means that they will be able to be stepped faster without loosing so much torque. Have you seen the motor drivers they use in the RepRap project?

Thanks your very informative answer, grumpy mike!

You are right, i’m not quite sure if the stepper motor i mentioned will be powerful enough, but at least it will allow me to experiment a bit with steppers before actually buying some new ones.

I checked out the motor drivers used in the RepRap project (this project is going to be a reprstrap further down the line):

  • unfortunately their latest driver uses surface mount components and specifically the Allegro A3982 stepper driver, which is rather affordable, but at this time i cannot build anything with surface mount components.
    -The older version of their driver uses a L297/L298 combo, which come in DIL packages which would be perfect, but their price is rather hefty (more than 10 euro a piece!)

Did anyone have a similar dilema when building their first cnc machine? (need the cnc to be able to do printed circuits…to make the cnc work!) what would you advise? (at this point i think i’ll go with the older stepper motor driver, tired of beeing stuck)