Re: lm317

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "afogassa" <afogassa@y...>
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?
>
> Thank's
> fogassa

Yes, as long as the total current draw does not exceed the ratings of
the first regulator and that both circuits use the same ground
reference. Take your 5V (I would use a fixed LM7805 instead) from
the regulated 24 side. If the transformer is center tapped you could
actually add another bridge from CT to one leg and get closer to
12VDC to feed the +5. You may have to mount the regulators on
heatsinks since dropping that much voltage at any current close to 1A
will generate some heat. Be sure to use bypass caps in input and
output close to the regulators per the specs to prevent oscillation.