Thanks Guys, I get it now.

Now I'm looking at the 7660; need to do some sums to see if 20ma is enough.
it probably will be. What are my options if I need more current, say ~50ma?
(can't see that I'll need more than that).

> -----Original Message-----
> From: Peter Onion [mailto:ponion@ALIEN.BT.CO.UK]
> Sent: 15 January 2004 15:04
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE:] Negative Voltage PS?
>
>
> On Thu, 2004-01-15 at 14:39, Hulatt, Jon wrote:
> > Hi,
> >
> > Given a source power supply nominally +12v (a car battery),
> can I use
> > a 7805 and a 7905 together to get a +5/0/-5 regulated power
> supply? or
> > am I misunderstanding what a negative regulator actually does?
>
> You'll probably end up with +5 and +10 rather that +5 and -5.
>
> You'll need a DC-DC converter to produce a real negative
> supply  (i.e. negative with respect to the "-" terminal of
> the battery).
>
> Peter
>
> >
> > Thanks
> >
> > Jon
> >
> > --
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