Technical help was Cap voltage rating (was Re: Power supply question.....

Dave,

It's been awhile since I sounded this app engineer "horn" so here
goes...

I find that the most reliable and easily had information when trying
to answer a question like this is to call a major mfr of the product
in question (like Mallory for capacitors). Notice I'm talking about
the original SOURCE manufacturer, NOT a distributor. Then ask for a
TECHNICAL applications engineer. (The word engineer is used more
often nowadays; be SURE you are talking to a REAL "applications"
ENGINEER. If possible. See the p.s. below) Mention that you are
trying to determine which of their parts or products (capacitors in
this case) will be right for your "project" (power supply here).

It can help to be "calling from" and "for your business" and speak to
them as a professional. I'm NOT saying you need to BS them, or
pretend to understand everything they are telling you! The job of an
applications engineer is to provide technical assistance for those
trying to use his or her companys' products correctly and
successfully... And believe me, the app engineer HAS spoken to
people with less of a "clue" than you...

Don't be afraid to appear "dumb". This person is SUPPOSED to know
more than you! I have learnt a great deal from these professional men
and women. They have often gone out of their way for me; even when
they know it is for a small order or use. Most people like to share
what they are passionate about; or knowledgeable in.

But if it IS for a larger project(volume for the mfr), be sure that
fact is mentioned...

IMO, The best way to determine if the info you have been given
is "good" is to make at least three calls to different competitive
mfrs. Like getting second opinions from healthcare or legal
professionals...

Hope this helps,

Ballendo

P.S. There ARE some good "app" engineers in sales positions. The
smaller the company, the more "hats" each individual wears... And
although it may be less expensive to use email, I find that I have
better results with phone conversations. Very often, the app engineer
WILL THEN direct me to a webpage or site for more info, or to prepare
me to ask better questions...

--- In CAD_CAM_EDM_DRO@y..., "dave_ace_me" <davemucha@j...> wrote:
> Hi Scott and all,
>
> I've been reading the threads about power supplies and caps and
> transformers and all with great interest.
>
> Seems to me that the preference is Torridoidal transformers and
huge
> capacity cap's, but the cap's voltage is not suposed to be lots
more
> than the expected voltage of the system. is: if you plan on a 35
volt
> power supply, 24 VAC trans + cap, a 50Volt cap would be good, but a
> 100 Volt cap would actually not be a good choice.
>
> On my 12 supply from my computer, it has 500 volt cap's. it is a
> dual power, 220/110.
>
> Then there is the voltage increase from the steppers when not being
> driven, but still spinning.
>
> Is there a good rule of thumb (or actual engineering principals ?)
> to size a capacitor ?
>
>
> Dave
>
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., scott wilson <swilson@d...> wrote:
> > have seen several pwr supply questions about caps....and it seems
> to me that if they are being used as brute filter caps people are
> using way to low a working voltage....in this case i would feel
much
> better with a 80-100v rating....and yes you can put them in parallel
> >
> > RC wrote:
> >
> > > Building my first power supply, needs to be approx. 42 volts @
10
> amps.... I will need a cap with a 19,000 mf value with at least 50
> v. rating, the question I have is, can one "add" the mf values,
> instead of using one large cap? And if so, how would they be
> connected, series or parallel?
> > >
> > > Thanks,
> > > RC
> > >
> > > [Non-text portions of this message have been removed]
> > >
> > > Addresses:
> > > FAQ: http://www.ktmarketing.com/faq.html
> > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > >
> > > OFF Topic POSTS: General Machining
> > > If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru Google.com to
reach
> it if you have trouble.
> > > http://www.metalworking.com/news_servers.html
> > >
> > > http://groups.yahoo.com/group/jobshophomeshop I consider this
> as a sister site to the CCED group, as many of the same members are
> there, for OT subjects, that are not allowed on the CCED list.
> > >
> > > Post messages: CAD_CAM_EDM_DRO@y...
> > > Subscribe: CAD_CAM_EDM_DRO-subscribe@y...
> > > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@y...
> > > List owner: CAD_CAM_EDM_DRO-owner@y..., wanliker@a...
> > > Moderator: jmelson@a... timg@k... [Moderator]
> > > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > > bill,
> > > List Mom
> > > List Owner
> > >
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/