On 9/18/05, Tom Sefranek <tcs@cmcorp.com> wrote:
> 
> 
> Dave King wrote:
> 
> >
> > Just wondering if anyone has run across a working schematic
> > for a DC voltage regulator. Input range is 20-48 and required
> > output is 12vdc @ 10Amps with a max of say 15-20A.
> >
> > I'm looking at one schematic that has the required output but
> > is too narrow in the input voltage range. So if you know of a good
> > one please let me know.
> >
> > Tia
> >
> > Dave
> 
> Are you looking for a switching or linear regulator?
> 
> A classic Linear regulator is the multi 2N3055 pass transistors feed by 
> a single 3055 driven by a 723.

  20A x (48-12)V = 720W

 Assuming 80W/transistor it means he need 9 transistors and a lot of
water + a pump recirculation on the heatsink.
Forget about this old methode. The NMR's built in 70'th were supplied
with that ugly thing. One great dummy design I saw, it was than one
transistor collapse it broke all supply.

There is no other solution than a switching supply. With a very good
dimensioned filter you may expect -40dBm noise at this load.

cheers
Vasile


> Most ARRL handbooks have the design including the transformer and 
> rectifier/filter section.
> There are better transistors and FETs that can be substituted.
> You will need a MASSIVE heat sink, or forced cooled sink.
>  I have designed and built linear supplies with transistor and FET 
> bricks for 100 amp+ performance.
> 
> Tom
> 
> -- 
>   *
>   |  __O    Thomas C. Sefranek   WA1RHP@ARRL.net
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