Robert Hedan wrote:
> Well, after reading that, I realize why I had joined the geckodrive Yahoo
> group as well. I don't know anywhere near enough about switching to make my
> own drivers. I can program a PIC, but then there's still the matter of
> getting the signal to the motors in a safe manner. But the Gecko system is
> waaaaay out of my budget for the time being. I had my eye on Xylotex for a
> cheaper alternative, but I never went ahead.
>
> I for one would be more than happy to buy my drives from you as long as they
> are not too expensive. I have 3 unipolar SP57B 24V steppers from COPAL
> Electronics, obsolete, can't find specs on Google. I'd love to be able to
> recycle those on my machine if possible, especially 'cause they cost me only
> $5 each.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7517401926&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1 Note that while you may already have motors, considering the deals that are
out there it can simply make more sense to get something like that. Even if
they're out, there is always someone else coming along.
Still 24V and unipolar is fairly easy. May need reverse diodes with 24V and
spikes, but they're easy enough to add. Any time I was running something like
that I'd planned to just solder the diodes to the transistor pins right on the
bottom of the board..
> All I'd need would be the assembled PCB driver boards, since you appear to
> have quite a lot of inventory on hand. :) I can take care of fabricating a
> box. I guess I'd start with 3 axis, and get that working first. All I'd
> need to know is exactly what input the drivers expect, and I should be able
> to feed it something, somehow, someday, from a PIC.
>
> Let me know if you are interested.
>
> Robert
> :)
>
Well right now it takes my own command format, that sends direct coordinates
on the parallel port. Was also planning to change that part to the serial port.
But I did plan to have a mode to read the parallel port pins and take steps
from that, so it'd be able to work with most any CNC program that runs the port
pins. It's easy enough to make the machine act dumb and just step when it sees
a pin change.
Needs a little other work and design. I have some nice little 5 and 12 V
switching supplies I got for $1, but this can power up with the FETs on since
the 7406 is normally high output. That makes the switcher not come up for the
logic if the motors are supplied from the same 5V supply. Takes some switching
on/off to get it up and running with these supplies. Wasn't too big a deal, but
it needs to have the gate supply off until the logic is up and has turned off
all the 7406s etc. Easy to do just haven't done it. Works fine with a seperate
supply, just shorts it for a tiny bit until the logic is up, or turn on motor
supply after the logic. The in progress version of the board was going to have
that and several other changes, mainly to a surface mount PIC though for some
more elbow room for additions. The original is a 40 pin DIP 877.
Alan