DIY Stepper Controller

[Maltaeron]

I have some steppers that I salvaged from an Epson printer that I want to use. Both steppers have 4 leads with 8 coils and a permanent magnet inside them. The last thing I want to do is buy some expensive controllers, is there some easier way to do this?

As far as my understanding goes, the only reason the steppers can't be directly connected to a microcontroller (atMega168 for me) is that the microcontroller can't support enough current.

Following this reasoning, could I use something like a MOSFET (4 for each stepper) to drive the steppers?

[airman00]

I have some steppers that I salvaged from an Epson printer that I want to use. Both steppers have 4 leads with 8 coils and a permanent magnet inside them. The last thing I want to do is buy some expensive controllers, is there some easier way to do this?

As far as my understanding goes, the only reason the steppers can't be directly connected to a microcontroller (atMega168 for me) is that the microcontroller can't support enough current.

Following this reasoning, could I use something like a MOSFET (4 for each stepper) to drive the steppers?

yes you could use MOSFETs, and your idea with the microcontroller is correct also

[Maltaeron]

So that would work with my steppers?   

That would be nice, also does anyone know what type of MOSFET I should buy? Just so I have an idea of what to look for from digikey...

Thanks 

[Ro-Bot-X]

I have some steppers that I salvaged from an Epson printer that I want to use. Both steppers have 4 leads with 8 coils and a permanent magnet inside them. The last thing I want to do is buy some expensive controllers, is there some easier way to do this?

The steppers have just 4 leads? Or 4 leads plus ground? How do you know there are 8 coils?

Steppers are bipolar, that means 2 coils and 4 leads, and unipolar, that means 4 coils and 5 or 6 leads. As far as I remember the Epson printer has bipolar steppers rated at about 3 amps. I'll check latter at work.

[Maltaeron]

I opened it up.  Only 4 leads, each lead connects to two coils opposite of each other. Maybe I'm talking about the coils the wrong way, but inside they are just bundles of wire round up together... The permanent magnet is the part that rotates. It is my guess that if I energize one lead, the magnet/gear will align with that leads two coils, without a ground. I sequentially switch the energized lead to take each step forward...

[paulstreats]

correct

[JonHylands]

Go to Google, and type in:

bipolar stepper control

and you'll get a zillion pages that tell you what to do. Here's one:

http://www.solarbotics.net/library/pieces/parts_mech_steppers.html

- Jon

[Admin]

does anyone know what type of MOSFET I should buy?

PWM optimized rail-to-rail MOSFET