Re: [CAD_CAM_EDM_DRO] lm317

Alan,

Here is the one I am using:

http://www.allelectronics.com/cgi-bin/category.cgi?category=480&item=PS-203&type=store

----- Original Message -----
From: "Alan Marconett" <KM6VV@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, June 05, 2004 5:24 PM
Subject: Re: [CAD_CAM_EDM_DRO] lm317


> Hi,
>
> Might be better to get a wall wart 5V supply, if you don't need much
> current. Maybe it can be mounted inside the 24V supply case. With big
> drops, you run the risk of a regulator shorting out, and getting an
> excessive voltage on the 5V output. A crowbar on the 5V output would be
> a good idea.
>
> Alan KM6VV
>
>
> Roy J. Tellason wrote:
> > On Saturday 05 June 2004 08:08 pm, afogassa wrote:
> >
> >>Hi All,
> >> I need to get 24 and 5v from the same transformer,I had in mind that
> >>I could set one lm317 to 24v. than feed another lm317 and set that to
> >>5v. The 24v would feed a relay card and the 5v a pic 18c452
> >> I've searched on the lm317 application notes and haven't found any
> >>thing like it,will it work?
> >
> >
> > Yeah, it'll work, depending. What you need to watch for with any kind
of a
> > regulator like that is the power dissipation. Dropping from 24V to 5V
is a
> > drop of 19V, which means that even pulling only half an amp, say,
you'll
> > still be kicking out 9 watts as heat. If you *must* go with this setup
then
> > I'd suggest a dropping resistor at the input of the second regulator,
to get
> > that down some. But why *must* you use only one transformer?
> >
> > The big issue here is how much current you need at each voltage. Can
you nail
> > that down?
> >
> >
>
>
>
>
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