Re: Power Supplie's

> >
> > I'm just looking for some confirmation on my power supply numbers.
> >
> > Four steppers rated at 4.5v/phase and 3.2A [all bi-polar
> series]. I plan to use Gecko 202's. Therefore 4.5v*20=90VDC, we know
> that the Gecko's only take up to 80VDC so thats my upper limit for my
> voltage. The ampers side of things 3.2*4=12.8 @70% duty per Gecko's
> doc's =8.96a or call it 9A. Does this all look correct?
> >
> > Does anyone know where I could find such a beast off the shelf? Or
> a place [ preferably in Canada] where I could purchase the components
> off the self to make it. Links to websites that explain building
> power supplies in English [ vs electronic-ese]?? Ball park guess's as
> to what this should cost ready made? I got one quote back with a
> total of nearly $1000USD with shipping.. however I was a bit off on
> my first set of numbers provided to them so that might have an
> effect.. Does this sound even in the ball park? I had $100ish in my
> head when I asked for the quote but then.. I have no idea so..
> >
> > Thanks
> > Jarrett Johnson
> >
>

If you would like to extend the functionality of your power supply and
turn it into a control box for CNC then check out our Power Modules
(ACM-100 and DCM-100) at http://www.CandCNC.com They make building a
power supply with front panel control an evening project instead of a
week (:-) The prices won't cause you to stagger, and all you need to
provide is the transformer, bridge and filter cap. You should be able
to get out by spending less than .50 per watt for an unregulated power
supply and AC and DC control.

On the transformer, you need to plan around about 60 to 70 percent of
your full load (all motors added together). Seldom will you hit even
that level. You will find that with the motors you have running in
chopper mode, your average current will only be 5 to 7 amps under
heavy loads.
Transfomers are big old chunks of iron that take overloads and peak
demands and intergrate them over time.

The RMS voltage of the transformer (normally the way they are rated)
should be .707 times the actual needed RAW DC you want. Bridges are
cheap and a 400V (or higher) at 25A bridge will only set you back a
couple of bucks. The filter cap needs to be about 2000MFD per amp of
expected draw. More is okay. The working voltage needs to be at
least 20% above the DC voltage you design for. There you just learned
how to design a basic DC unregulated supply!

Shop www.bgmicro.com, www.MPJA.com and www.alltronics.com for deals
on transformers and other parts you need. MPJA sells a 24V 10A
transformer for 18.00. What can you do with 24V? Well, that gives
you almost 34VDC out @ 10A. You need more volts? Buy two and series
the secondary, and parallel the primaries and bingo, you get around 67
VDC at 10A to run Gecko's. In your example the 67 volts would work
fine to run the Gecko's. There are hundreds of units (commercial and
otherwise) running Gecko's at 48 to 70vdc with no problem. There is
even a way to build two basic 34VDC supplies (each with it's own cap
and bridge) and "stack" them so now you have a 34VDC supply AND a
67VDC supply. (never mind, forget I said that!)

The DCM-100 we sell is a safety overvoltage protector and active drain
(load) to function as a dynamic brake at shutdown or in the case where
the DC voltage might exceed the rating of the motor driver.

If you will download the manual for the ACM-100 off the website there
are some ideas on building a commercial grade power control box with
the motor drives built in.

Of you need help with a simple wiring diagram (simplier than in the
manual) then let me know.