I had some stepper motors from old disk drives and other electronics devices lying around. Those were typically designed to be driven with 12V voltage and take few hundred mA of current per phase and had five or six wires (four phase).
I thought that it would be a good idea to turn them to some useful applications (for example homemade CNC) by adding a suitable stepper motor controller to control them. I was looking for a controller that accepts traditional step + direction type control interface. And I was looking for a simple to build and inexpensive system that can be easily and cheaply built (so single chip solution would be perfect).
With some web searching I could find some stepper motor driver modules that would fit to my technical needs, but the downside of then was that they seemed to be a little bit expensive for simple experimenting when price starts at around 50 euros. I was looking for something less expensive.
There are many links for stepper motor controller circuits. None of them seemed to be exactly right. I did not want to have many components and I did not want to put in microcontroller. Some web searching gave more circuits, but nothing exactly right.
Then I saw something that looked promising. There was a SAA1027 based stepper circuit. That IC seemed to be exactly what I was looking for. But then came the bad news. It seems that this IC is not made anymore and availability of SAA1027 was really bad.
Back to drawing board. I looked around on the stepper motor controller ICs from the component sources I can easily use. It took some time to go through them and most I were something like 2-3 IC solutions to drive stepper. Too complicated I though. I would like to have single chip and something that costs less than 10 euros.
Then I found NJR3517D2 that is available through Elfa easily at reasonable price (less than 8 euros). I ordered one IC and started experimenting. Very quickly I built a working stepper motor controller to a breadboard. This IC looks very promising. If you are looking for a simple solution for stepper motor controlling, check this IC.