From: Groepaz (groepaz_at_gmx.net)
Date: 2004-01-16 09:05:52
On Friday 16 January 2004 08:42, Spiro Trikaliotis wrote:
> On Fri, Jan 16, 2004 at 08:26:40AM +0100, Baltissen, GJPAA (Ruud) wrote:
> > I noticed that this 9V AC is rectified as well, inside the C64. This
> > means there is no galvanic isolation and thus no free use of the 9V
> > AC.
>
> This is used for the generation of the +5V ("CAN +5V" in the schematics)
> of the VIC-II, and the +12V for the VIC-II and SID. The +9V is even
> rectified and used unregulated for the cassette motor driver.
>
> Anyway, I must admit I do *not* understand how the +12V is generated of
> the 9VAC, this part of the schematics is beyond my understanding of
> electronics. :-(
some capacitors and diodes.... (google "spannungspumpe" or "ladungspumpe").
you can even generate +-15v from a 5v source that way :) (most rs232 driver
chips contain that type of circuit)
gpz
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