CAD CAM EDM DRO - Yahoo Group Archive

Re: [CAD_CAM_EDM_DRO] Re: Capacitors for Geckos when using fuses

Posted by Jim Brown
on 2002-10-25 20:33:56 UTC
Yeah! I got it all hooked up and my mill is now under cnc!
I just wish that I knew how to setup Turbocnc correctly.
I tested with Mach1 and these puppies scream. But under Turbocnc, they seem to miss alot of steps.
Mach1 was easy for someone like me, who has no prior experience with CNC, to setup and tune the motors, but I cant figure out how to setup Turbocnc right.
Regards,
Jim
turbulatordude <davemucha@...> wrote:I agree with you on this. for less than $1.00 per cap, you enjoy
increased protection for the $$$ Gecko. I too do this regardless of
how close to the power supply the Gecko's will be.

Dave

--- In CAD_CAM_EDM_DRO@y..., Jim Brown wrote:
>
> That I dont know, as all of this is very new to me.
> But I'm going to use the 470uF caps anyway as per Mariss' suggestion. After all, he would know better than anyone else, considering the Gecko's are his creation.
> I cant see how it would hurt.
> Thanks for the help.
> Regards,
> Jim
> turbulatordude wrote:Hi Jim,
>
> I think you are correct regarding the switching powers supply.
>
> the calculation does reveal an interesting phenonimon. (sp?)
>
> with the current remaing constant at 9 A,
> a 24 V power supply (home built) requires 20,000uF cap
> a 48 V power supply (home built) a 10,000uF cap.
> the higher the voltage the lower the cap, but in the case of a
> switcher, I think you are correct that it's primary function is
> handling ripple.
>
> The question I would pose then is if one had the switcher remote, and
> the 4,700uF (your app) cap next to the Gecko, would one still benefit
> by the 470uF at the Gecko itself ? I think not.
>
> Dave
>
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., Jim Brown wrote:
> >
> > According the the gecko white papers(verbatum), "If a linear
> regulated or a switching power supply is used then a large capacitor
> should be placed across the output terminals. A 2000uF-10000uF
> capacitor should do."
> > That is why I chose a 4700uF cap. for the power supply output
> terminals... It's about right in the middle of Mariss' suggestion of
> a capacitor for a switching power supply.
> > He wasnt specific as to what voltage rating for this cap, he was
> only specific as to what uF value (2,000-10,000uF)
> > Your formula for computing the value of a capacitor, I think, is
> for when building your own power supply, in conjunction with a bridge
> rectifier and transformer.
> > I dont think this applies to when you are using a regulated or
> switching power supply. The cap mentioned above, is placed on the
> output terminals to insure that the ripple current stays within the
> demand of the drivers current requirements. That is what I get from
> the papers. I may be wrong about this though.
> >
> > Thanks
> >
> > Regards,
> > Jim
> > turbulatordude wrote:Hi Jim,
> >
> > you ask two questions here.
> >
> > #1 470uF AT THE TERMIANL connector of the Gecko. required if you
> place
> > ANYTHING between the main cap and the gecko OR if the lines are
> longer
> > than the listed 18 inches.
> >
> > there are lots of posts that address this. the main thing is that
> the
> > switching of the gecko will encounter voltage spikes from the
> stepper.
> > the on-board cap on the gecko can handle some of this while the
> main
> > cap handles the rest.
> >
> > and yes, as long as the voltage rating of the cap is well over the
> > power supply the cap is fine. your 24 volts power supply will
> operate
> > fine with a 35V cap.
> >
> > #2 main capacitor. check the gecko white paper on the cap sizing.
> > again, as long as the voltage well above the power supply it is
> fine,
> > but the cap size needs to be suffiecnt for the amp load of the
> system.
> >
> > You didn't list the total amps of all your steppers, but you need
> to
> > total all motors for the main cap sizing.
> >
> > cap uF rating is = (80,000 x total motors amps) / ps voltage
> >
> > example is if you have 3 steppers at 3 amps. you have 9 amps total
> >
> > 80,000 x 9 = 720,000
> > 720,000 / 24 = 30,000uF
> > so you would need a total of 30,000uF with a rating of 35 volts.
> >
> > www.jameco.com has them for low cost, about $5.00 each for 10,000uF/
> > 35volt
> >
> > the 470uF/35volt are less than $1.00 each.
> >
> > Dave
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@y..., "jagco1998" wrote:
> > > I have a few more dumb questions....
> > > I dont want to burn anything up, in using components that are
> > > incapable of handling voltage/currents correctly.
> > > The gecko white papers say that when using a 5A fast-blow fuse to
> > > protect the drivers, that a 470uF 100V cap needs to be placed on
> > > across power leads.
> > >
> > > My 1st question is this..Can a 470uF 35V cap be used, instead of
> > > 100V as the white papers suggest? I can find them at every elec.
> > > supplier in my small town of residence.
> > >
> > > I am only using a 24Vdc/10A switching power supply to power 3
> gecko
> > > G201's, and have already placed a 4700uF 35V cap across the PS
> > > outputs(I couldnt find anything larger than 35V. I live in the
> > > sticks!)
> > >
> > > Also, is the 4700uF 35V cap going to be sufficient for my PS?
> > > Without the cap, a dig. voltagemeter across the output leads tell
> me
> > > that the power only fluctuates from 24V to 24.2V no load.
> > >
> > > I realize that this probably will become a substantially larger
> > > fluctutation once a load is applied.
> > >
> > > Will a spike or short in the power going to the motors damage
> them
> > > if not protected with a fuse? Would it be wise to also fuse the
> > > lines going to the motors also, or is this necessary?
> > >
> > > Any suggestions or comments will be appreciated.
> > > Thanks.
> > >
> > > Regards,
> > > Jim
> >
> >
> >
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Discussion Thread

jagco1998 2002-10-24 10:45:21 UTC Capacitors for Geckos when using fuses turbulatordude 2002-10-24 12:18:11 UTC Re: Capacitors for Geckos when using fuses Jim Brown 2002-10-24 12:59:19 UTC Re: [CAD_CAM_EDM_DRO] Re: Capacitors for Geckos when using fuses Tim Goldstein 2002-10-24 13:11:09 UTC Re: [CAD_CAM_EDM_DRO] Re: Capacitors for Geckos when using fuses turbulatordude 2002-10-25 09:47:47 UTC Re: Capacitors for Geckos when using fuses Jim Brown 2002-10-25 17:22:41 UTC Re: [CAD_CAM_EDM_DRO] Re: Capacitors for Geckos when using fuses turbulatordude 2002-10-25 19:06:40 UTC Re: Capacitors for Geckos when using fuses Jim Brown 2002-10-25 20:33:56 UTC Re: [CAD_CAM_EDM_DRO] Re: Capacitors for Geckos when using fuses