This week I found again a bipolar step motor in an old scanner but it looks bigger then the one I found before, so i decided i'll try again to get a step motor running.
When I asked last time about step motors I got a lot of replies that I should just use a prebuild H-Bridge like the L293. I'm thankful for all the replies, but as I'm new to electronics I prefer to build the circuit myself and understand what's going on and why. That's why I'll try to build the H-Bridge myself, like I "designed" in the schematics below:
All the transistors are NP2222A, the diodes are 1N4001 and the step motor is a STH-39D1126.
To rotate the motor clockwise I would basically program the Arduino as following:
D0 D1 D2 D3 - + - - - - + - + - - - - - - +
where D0, D1, D2 and D3 are the digital pins and + stands for HIGH and - for LOW.
My questions are:
Will this theoretically work or are there any "big" problems?
Which restistance should R1 - R4 have? I know that the resistors are there to protect the arduino from to much current, but how do I calculate the value?
How can i figure out which voltage I should use for my step motor? It's an STH-39D1126, but I can't find any datasheet.The only thing i know is that is has a coil resistance of 4,1ohm.
Are the transistors and diodes ok for this purpose or should I use others? Sorry, I know basically how they function, but when it comes to there specification, I'm pretty lost.So I would be really grateful if somebody could explain why they are "good or bad" for this purpose. But this would be an extra task for somebody who is explaining mood :).
Thank you very much for any reply.