Gianmario.Scotti_at_nokia.com
Date: 2004-01-16 01:34:07
Excellent point, David. Here is an amended schematic, that takes your
note into consideration. Further suggestions welcome.
mario
> -----Original Message-----
> From: owner-cbm-hackers@cling.gu.se
> [mailto:owner-cbm-hackers@cling.gu.se]On Behalf Of ext David Wood
> Sent: 12 January, 2004 13:47
> To: cbm-hackers@cling.gu.se
> Subject: RE: C64 power supply replacement
>
>
> The primary reason for separate windings, as far as I know, is to get
> isolation between the +5 ground and the 9vac. The SX-64 user
> port is known
> for not working with certain devices because it's not
> isloated like the
> breadbox psu is.
>
> -David
>
> On Mon, 12 Jan 2004 Gianmario.Scotti@nokia.com wrote:
>
> > I actually knew that the transformer in the original C-64
> PSU has a transformer with two windings, but I am not sure
> that's really necessary. I think a single winding would be
> adequate, given enough VA of the transformer. If that's not
> the case, I'd like to hear why.
> >
> > In any case, it's really trivial to use two windings
> instead of one, in the design I presented. It doesn't
> increase complexity at all. When I get home I'll prepare
> another schematic, to work with commodore's original transformer.
> >
> >
> > cheers!
> >
> >
> > mario
> >
> >
> >
> >
> > -----Original Message-----
> > From: owner-cbm-hackers@cling.gu.se
> > [mailto:owner-cbm-hackers@cling.gu.se]On Behalf Of ext
> Hársfalvi Levente
> > Sent: 12. January 2004 11:50
> > To: cbm-hackers@cling.gu.se
> > Subject: Re: C64 power supply replacement
> >
> >
> > Hi!,
> >
> >
> > Gianmario.Scotti@nokia.com wrote:
> >
> > > A transformer doesn't have separate taps for 9 V AC *AND*
> regulated 5 V :o)
> > > And I did put a fuse in the 9 V AC line in the schematic.
> >
> > The transformer in the C64 PSU has two independent
> secondary circuits, 9V AC
> > each. One of these circuits is rectified and regulated (5V
> DC), the other is
> > just brought to the C64 (only a fuse is used).
> >
> > See these schematics:
> >
> >
> http://www.funet.fi/pub/cbm/schematics/computers/c64/c64-power
supply.gif
> http://www.funet.fi/pub/cbm/schematics/computers/c64/c64extps.gif
>
> As you see, the two outputs (5V dc, 9V ac) are fully "independent" in the
> original PSU design. They aren't grounded together in the PSU.
>
>
> Regards,
>
> L.
>
>
>
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>
>
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