[sdiy] Phantom Power Supply

[Theo]

Depends on the design actually.
Its a maximum output of  35V or so against the reverence voltage.
If the reverence has been raised to sufficient level the 317 may even output
400V.

Theo


----- Original Message -----
From: Czech Martin <Martin.Czech at micronas.com>
To: Dave Magnuson <resfreq at hoohahrecords.com>; <synth-diy at dropmix.xs4all.nl>
Sent: Friday, August 29, 2003 6:33 PM
Subject: RE: [sdiy] Phantom Power Supply


> Ok, if the datasheet tells you that the LM317 can not
> have such high input, output voltage, then do not do it.
> I do not have it in front of me, but this again this
> recommended and abs. max. game.
>
> There is another thing: there is some limit for the
> output short protection. The 317 seems to have a limit
> for the output voltage, where the protection circuit
> will not keep it in SOA.
>
> Some LT regulator has better performance in this case.
>
> All from my head, late now, time to go home.
>
> m.c.
>
>
> > -----Original Message-----
> > From: Dave Magnuson [mailto:resfreq at hoohahrecords.com]
> > Sent: Freitag, 29. August 2003 18:09
> > To: synth-diy at dropmix.xs4all.nl
> > Subject: [sdiy] Phantom Power Supply
> >
> >
> > Hi List,
> >
> > I was researching a simple 48V phantom power supply, and I keep coming
> > across designs using the LM317T regulator.  They typically
> > use an 18-24VAC
> > transformer and a voltage doubler, then rectify and regulate to 48VDC.
> >
> > My question is this:  The LM317T is listed as being
> > adjustable to 37VDC,
> > yet all of these designs claim a 48VDC output.  Do you think
> > it's unwise to
> > use (abuse?) the 317T in this way?
> >
> > I don't want to build something that's going to burn out in a
> > year, yet the
> > sheer multitude of phantom supplies like this makes me think
> > it must be
> > ok...  Perhaps the very low current used in phantom power
> > avoids stressing
> > the part too much?
> >
> > If all else fails, I'll pick up a TL783 regulator... But
> > unfortunately I
> > can't get it locally (and I can get an LM317T down the street)
> >
> > Thanks for your input!
> >
> > Dave Magnuson
> >
> > Resonant Frequency:
> > resfreq at hoohahrecords.com
> > http://www.hoohahrecords.com/resfreq/index.html
> >
>
>