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.