From: Ryan Underwood (nemesis-lists_at_icequake.net)
Date: 2004-01-18 20:15:33
On Fri, Jan 16, 2004 at 01:43:26AM +0200, Gianmario.Scotti@nokia.com wrote:
> This seems almost identical to what I suggested, except it's
> somewhat bad. Read my comments below.
>
> > -----Original Message-----
> > From: owner-cbm-hackers@cling.gu.se
> > [mailto:owner-cbm-hackers@cling.gu.se]On Behalf Of ext Ryan Underwood
> > Sent: 16 January, 2004 01:06
> > To: cbm-hackers@cling.gu.se
> > Subject: Re: C64 power supply replacement
> >
> >
> >
> > I had a design proposed to me by a friend; advantage is that it is
> > easily built from Radio Shack parts but I would like some
> > opinion on it.
> >
> > - Start with 120V / 12.5VAC transformer
> Why not 9V AC secundary?
Because I need parts I can easily get (read: at Radio Shack...) ;)
> > - Use voltage divider to derive 9VAC from secondary and send that
> Do you mean, a two-resistor voltage divider? I hope not.
Yeah, such as:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/vdivac.html
> > straight to the C64 (it needs no regulation, correct?)
> > - perhaps a bridge rectifier on secondary?
> > - Send 9VAC through a 7805 regulator set to 5V
> > - Filter ripple from 5V with a RC pair
> Actually, an RC pair would consume way too much energy. Same as the
> voltage divider you mentioned previously.
> > - Zener protection on regulator output to prevent short
> > failure damaging C64
> Not necessary! The 7805 NEVER shorts. It's an incredibly
> well-protected and well-protecting IC.
I didn't know that. At least it seems like every other regulator in the
world likes to pretend it is a wire at some times...
BTW, I thought your design was simple and elegant, but I just took
another angle at it (from the cost reduction standpoint).
--
Ryan Underwood, <nemesis@icequake.net>
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