Re: [CAD_CAM_EDM_DRO] Re: Power supplies (correction)

Hmm....not to split electrons, but for the sake of clarity to the
non-formally trained electrical aficiondos out there, did you really mean to
say that an undersized cap would possibly cause it to smoke? Undersizing a
capacitor will cause ineffective DC smoothing, which is why it is there in
the first place, however will never to my knowledge cause failure of the
cap. That said, electrolytics such as those we use in these power supplies
are rated at a DC voltage in addition to their capacitance rating, and
applying a reverse voltage or voltages in excess of the DC rated voltage
will surely cause smoke and possibly a nice little explosion to boot :-).
This is why, for those of you who may not have been aware, most
electrolytics have those little v-shaped scorings on the top of the can, so
as to permit release the gas pressure before they take off like an Estes
rocket or worse! (like the time I almost lost an eye as a stereo-tv tech in
my college days when a 1,000 mfd cap dented the ceiling after passing within
an inch of my eye).
That notwithstanding, if your supply filter cap is too small, you may indeed
see false resets, or other funky problems difficult to explain, due to
undervoltage spikes and such, so it is of course important to add sufficient
filter capacitance.
Anyhow, just a friendly correction to avoid confusion.









R. William Kichman, P.E.
Kichman Engineering Associates
103 Old Furnace Road
Cornwall, PA 17016-0643
tel/fax 717/270-0714

----- Original Message -----
From: "dougfennell2000" <dfennell@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, July 29, 2003 10:12 AM
Subject: [CAD_CAM_EDM_DRO] Re: Power supplies


> Mike, let me correct an error I made in an earlier post - Doug
> Fortune is right; I left off a zero - the cap needs to be a 22,000mfd
> cap and not a 2200mfd. It will be about the size of a can of coffee
> creamer. If you use a 2200mfd cap you will let the smoke out of it
> <g>.
>
> Doug Fennell
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "mmeyers1111"
> <mmeyers1111@y...> wrote:
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Tim Goldstein" <timg@k...>
> > wrote:
> > > > -----Original Message-----
> > > > You freak'n guys in this group are like the ham radio guys 20
> > years
> > > > ago. Ya'll understand what each other are saying, but people
> > like
> > > > me of less intelligence turn to the person next to them and
> > > > go... "wa did he just say???"
> > > >
> > > > That might not sound like a compliment, but it is. Kinda
> > backhanded
> > > > of course.
> > > >
> > > > Now listen... I'm an idiot ok? So get the ham radio 'belittle
> > the
> > > > stupid redneck' thing over and cough it up... where might
> > someone
> > > > like me get a wiring diagram of that power supply you just
> > > > described?
> > > >
> > > > You guys always make newcommers pay dues via embarrassment
> don't
> > > > ya??...
> > > >
> > > > he he ha ha :-)
> > > >
> > > >
> > > > Mike
> > >
> > > No one is trying to embarrass anyone. There are a number of great
> > > references we steer anyone that asks towards. If you have not
> read
> > the
> > > stepper white paper on the Gecko Drives site than that is the
> first
> > > thing you need to do to start bootstrapping yourself to some
> > knowledge.
> > > In the power supply section page 3 you will see a schematic of a
> > basic
> > > linear power supply.
> > >
> > > http://www.timgoldstein.com/cnc/geckoG320wiring.htm will show you
> a
> > > power supply as part of connecting some Gecko G320 drives. It is
> > using 2
> > > transformers along with the switch and fuse that is not in the
> more
> > > basic circuit in the Gecko white paper.
> > >
> > > Tim
> > > [Denver, CO]
> > > Sherline & Taig products at Deep Discount
> > > Mach1 & DeskCNC with credit card ordering
> > > www.KTMarketing.com/Sherline
> > > e-mail me at Timg @ KTMarketing.com for items not yet listed
> >
> > Ha ha only 1/2 kidding Tim... however, you guys are in a class all
> > by yourselves *Twilight Zone music playing in background*
> >
> > Thanks so much to everybody for the postings re my question on
> power
> > supplies. Wow! Very helpful!
> >
> > Mike
>
>
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