feedback: step motor controller

[justDIY]

I recently got inspired to mess around with some steppers I salvaged from old printers. I tossed together a real quick driver based on a uln2803, and toasted it trying to drive the 1a stepper. It ran the ~300ma stepper ok, but got kinda hot. Using one '595, I have control for two unipolar motors.

So, I looked around a bit, and decided to build version two using discrete switches instead of an array. A lot of designs I dug up used darlingtons instead of mosfets. Is there some advantage to using a bjt verses a fet in this application? It would seem to me the very low voltage drop in a fet would be an advantage, and given improvements in "logic level" fets, having a low gate voltage seems ok for at least a few amps.

anyway, here's the 1000 words:
**broken link removed**


fets:
Fairchild HUF76407, logic level, to-251aa package

flyback diode:
12a surge schottky diode

control:
3-wire serial interface, expandable

logic supply:
5v regulated and filtered

motor supply:
1a current limited, up to 12v

 

[rajivdey]

i want to know that how i can make the of microcontroller in c language

 

[3v0]

I like it.

Mouser cross matches the mosfet with a surface mount part STD12NF06LT4. About half the price.

 

[Hank Fletcher]

Hey, justDIY, what did you mean by "old printers?" I have one I salvaged out of the neighbours trash (yeah, I'm one of those guys), and it looks like an hp inkjet about five years old or so. I've wanted to get into steppers, but for want of time, so maybe I should tear open the printer and get what I can? Also, and I know this may be contrary to the spirit of DIY, but the SN754410 IC has built-in flyback diodes. Although you'd need two to drive two motors, it could cut down on overall components.

Incidentally, where I live right now everybody puts their big trash (you know, stuff that can't fit in a garbage can) out on the same night, one night a year. Man, the scavengers come out of the woodworks! It's like a garage-saler's free shopping spree.