[sdiy] Power Supply Design Questions

[male man]

speaking of power supplies, i have am putting together
a small system using a power one bipolar supply rated
at 1amp.  the instructions mention a possible fan for
air circulation.  this will be in an enclosed case
with the modules.  im wondering how important this fan
is.  what if i am not drawing anywhere near 1 amp? 
what about the heat affecting vco's and such?  thanks
for the help.

skot



--- patchell <patchell at silcom.com> wrote:
> If you go here:
> 
>    
>
http://www.silcom.com/~patchell/powersupply/powersupply.html
> 
>     You will find a scan of something I wrote up on
> how to select a
> filter capacitor for a three terminal type
> regulator.  I generally allow
> for 3 volts drop, sort of a margin of saftety.  You
> have to remember
> that there will be supply ripple going into the
> regulator, and you need
> to make sure that the voltage never goes below that
> magic point.  So, it
> is not so much the transformer you have to select,
> but rather, the
> filter capacitor.
> 
> Scott Gravenhorst wrote:
> 
> > Some questions I have:
> >
> > At what input voltage should a LM78xx or LM79xx
> type
> > regulator be run for minimum heat?
> >
> > I read in data sheets that 2 volts is the usual
> value for
> > dropout voltage (at 1A).
> >
> > Would this be the point (well, somewhat above it)
> at which
> > the regulator would heat up the least?
> >
> > Operated so, does this also mean using a
> transformer with
> > better current capabilities?
> >
> > Thanks all.
> >
> >
>
=========================================================
> > - A smoking gun is one that's already been fired.
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> > - What good are laws that only lawyers understand?
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> >
> > -- Scott Gravenhorst | LegoManiac / Lego Trains /
> RIS 1.5
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> > -- FatMan: home1.gte.net/res0658s/FatMan/
> > -- NonFatMan: home1.gte.net/res0658s/electronics/
> 
> --
>  -Jim
> ------------------------------------------------
> * Visit:http://www.silcom.com/~patchell/
> *-----------------------------------------------
> * Come to the Pacific Southwest DIY Meet
> * April 12, 2003 10am-5pm
> * Santa Barbara, CA
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> 


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