Stepper motors 1

A motivation for this (not only) post was a homemade cnc drill, to which sadly I cannot find a link now. But googling for a while will show You how much of this is really out there. So I immediately wanted to build it for myself.

The first problems where the stepper motors. I read something about them and knew, that there are really 3 types of motors on the market: bipolars, unipolars and hybrids. After some days I have managed to buy some used steppers on our polish eBay (allegro). The type I bought was a KT42JM06-006. This according to the transcription of the code (this pdf, on page 29) was a 3 phase hybrid stepper motor with 0.6 degree per step, so a very precise one. On the yellow sticker there was some additional information like the voltage: DC24V, 1.5A/2 Phase.

So I had the motors, but what about the driver? I had no idea how to start with it. The dedicated drivers for this motor would cost a fortune, and I wanted to: a) create everything from 'scratch' b) spend a fortune on something else. That was a motivator to start reading the motors documentation. I found there the exciting sequence.

Image 1. The Windings and the Exciting sequence of the KT42JM06 motor.

OK, that will be a tricky one, because that is a hybrid, not a bipolar, nor a unipolar, so the usual drivers will not be good for it. After a while of thinking and researching the google I found 2 Ideas: 1 and 2, from which I have mended myself (inspired by the second Idea :)) a circuit which is presented in the Image 2.

Image 2. The proposed circuit. Created using TinyCad.

I am not very experienced in any type of transistors (mainly because it is not very necessary for a software developer in everyday work). So the facts stop here, but the dream carries on. I think there are tons of different transistors on the market, and few of them would be suitable for this task. My expectations considering the transistors in this circuit are as follows:

• The gate of each transistor is controlled by a 0-5 voltage, which causes the transistor to conduct the current or turn itself off respectively.
• The current conducted by the transistor will be enough to steer the stepper.
• The transistors will not be destroyed during the work.
• .... will they get hot? ...

 I have chosen the FET transistors, but as I said, I don't have much experience in such transistor containing circuits (I played a lot with the logical gates and so one, but not the transistors only). So when You have any suggestions to this stepper motor driver I am all ears.