Biploar Stepper Driver
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David Duffy wrote:
> >PS. Is this for a little bot?
> Yes, but the unipolar steppers are looking much cheaper to drive.
> 5V steppers would be better as I already have 7.2V 1700mAH nicad.
> The 5.25" FDD ones don't run very well from much less than 12V.
> I might pull another couple of FDD's apart & see what drivers they use.
Ok, so now we're talking REALLY cheap? Try 4x BC337
transistor, as unipolar, they are about 20c AU each.
Or use a ULN2803A $5.95 AU at wes. This has 8
darlingtons in a 18 pin DIP and will drive two
unipolar motors up to about 500mA per phase.
I have done what you are doing, I think, see my
page at http://www.ezy.net.au/~fastvid/deskbot.htm
I used 2 x ULN2003A chips, as they only have 7
darlingtons in each chip. This was about the same
price as 1 ULN2803 but gives me another 6 outputs.
Probably would be wise to choose battery to suit
motors, if you want any power. The M54646 chip is
chopper constant current bipolar, and will give
41% more torque as it's bipolar, and will give
MUCH higher torque at speeds due to the chopper
system, and more efficient battery use. For the
extra $20 AU total I would go that way. :o)
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