to Low ESR or not to Low ESR, that is the ... ( was Re: GECKOS 201

OK, that is fair enough.

I see the huge and coninual ripple at the power supply. that will
last as long as power is applied.

The cap on the Gecko sees the spikes of the kickback of the motors as
they are slowing. therefore the duration of spikes and the frequency
of their occurance is small.

Ummmm.... I wonder if Dan remembers the type of movement he was doing
when he did the test that brought about this thread. Long cuts or 5
axis stuff ?

At the terminals of the Gecko, the 470 is between the cap on the
Gecko and the cap at the power supply. I haven't done any frequency
analisys to see what the cap is seeing, and I haven't put a scope on
it so see what it is seeing.

I think for fun, I'll re-wire one of my steppers to parallel and
monitor the temperature of the drives. give me a good reason to
break out my 32 point temperature data logger. I'll have to think
about the proceedure a little to get some base line data...... and
get one of those mechanical pencils... and some wire.... and one of
those little plastic thingies for my shirt pocket.......

Dave

--- In CAD_CAM_EDM_DRO@y..., "jeffalanp" <xylotex@h...> wrote:
> Hello Dave,
> As I understand, from what the article said, a low ESR cap will
be
> less affected by ripple, thus heat up less, thus last longer. The
> higher the ESR, the more it will be affected by the ripple, thus
heat
> up more, and not last as long.
>
> So, it looks like if you want the 470uF cap to 'protect' the
Gecko
> longer, the cap itself has to last longer. A cap with a high ESR
> wont last as long, so when it looses effectiveness, it's value as
> a 'safety valve' is diminished.
>
> What I think it really comes down to: is the 470uF cap going to
be
> adversly affected by ripple current at the terminal of the Gecko.
If
> not, then a cap with a specifically low ESR isn't required.
>
> Jeff
> www.xylotex.com
>
>
> --- In CAD_CAM_EDM_DRO@y..., "turbulatordude" <davemucha@j...>
wrote:
> > Hi Jeff,
> >
> > interesting article and the web page added a neat saying about
the
> >
> > "The reliability of any piece of electronics is inversely
> > proportional to the number of electrolytic capacitors in it"
> >
> > I do understand the ESR, but the 470uF at the input on the Gecko
is
> > there to filter the ripple from the drives, or rather from the
> motors
> > as they are switched off. The 470uF is there as a safety valve
so
> to
> > speak and will not enhance or detract from the performance of the
> > Gecko or the power supply.
> >
> > I just don't see any major benefits from a low ESR vs. a more
> common
> > cap.
> >
> > Dave
> >
> >
> >