The Geckos have a really good reputation, but there are apparently=20
clones of them floating around, so buy from a reputable source.  I can't=20
remember when last I saw used ones for sale though.

I've tinkered with a handful of different stepper motor drivers, and my=20
favourite for performance and cost is the IM483 and IM805 units. They're=20
robust with opto-isolated inputs, proper heatsinking, etc. They're=20
generally quite expensive, but I've found them used on Ebay for quite a=20
bit less... IIRC in the $35-$50 range for the IM483, and around $60-$70=20
for the IM805.

I'm not sure what Gecko does electronically to compensate for=20
resonance.  I've never seen any resonance with my uses (homebuilt CNC=20
mill with IM805's, 4-axis workcell with IM483's, etc), but from memory=20
you can compensate for resonance with (a) more microsteps, (b) adding=20
some (mechanical) load, (c) using mechanical dampers (there are simple=20
DIY versions that are essentially a disc-shaped cylinder with metal=20
balls in it mounted on the motor shaft to break up resonance).

Cheers,
-Neil.




On 6/26/2016 5:44 PM, V G wrote:
> The cheap stepper drivers I got with my 6040 CNC machine are pretty garba=
ge
> (prone to missing steps, interference, one of them even failed, etc.), so=
 I
> was looking into replacing them with far better ones.
>
> Everyone seems to recommend the Gecko stepper drivers because they're
> apparently designed well and quite rugged. I was looking at this one:
> http://www.geckodrive.com/geckodrive-step-motor-drives/g250x.html but at
> $81.00 USD each, they're insanely overpriced. I don't think I could buy o=
ne
> of those just on the principle of not paying for something that
> outrageously priced. So I decided to try and make my own.
>
> There are plenty of schematics available on the internet already, but the=
y
> mostly seem to use driver ICs with integrated MOSFETs and are under-power=
ed
> for my needs. Then I found this IC: http://www.ti.com/product/drv8711 whi=
ch
> seems to meet all my requirements (micro stepping, external MOSFETs).
> However, there's one problem that the Gecko guys claim to solve that I
> don't see mentioned by any stepper driver IC manufacturer - midband
> resonance compensation. Googling for this doesn't seem to provide any
> information on how to solve it yourself, just more ads
> <http://www.geckodrive.com/support/step-motor-basics/mid-band-instability=
..html>
> for Gecko.
>
> Can anyone link me to some information on midband resonance so I can try =
to
> implement a solution myself? Anything would be great, including technical
> literature, examples, source code, whatever. The TI DRV8711 seems to
> provide all the functionality I need except midband resonance compensatio=
n
> and I can probably make a good quality driver for around 10-20% of the co=
st
> of an overpriced Gecko.
>
> -- V

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.