Commodore 64 Power Supply

Roy J. Tellason rtellason at
Sun Jun 29 19:26:27 CDT 2008

On Sunday 29 June 2008 20:08, Ray Arachelian wrote:
> Seth Morabito wrote:
> > Does anyone know of a commercially available replacement power supply,
> > before I go off and build one?  A linear supply would be trivial to
> > design, but I've never done a switching power supply, which I suppose
> > would be greatly preferable.  The trick with the C64 is that it
> > requires both 9V AC and +5V DC.  (I've considered frankensteining
> > together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
> > cable, but it just feels so very very wrong).
> Sounds like you just need a single 9VAC power supply, a bridge, a
> voltage regulator, and perhaps some caps to clean up the signal a bit.
> The trick is to provide enough wattage.


The 9VAC has to be a separate transformer winding from the one that provides 
the +5VDC eventually,  because of how it's used...

One thought that came to me after my previous response was posted is that if 
one happens to have a really trashed 1541,  that transformer could be used, 
as well.  In fact,  I built a bench supply that worked that way,  though my 
attempts to try and run two 64s off it at the same time never worked,  even 
though I had separate regulators for the two outputs.  Too much interfence 
between the two.  Any time I'd hook two computers up and turn 'em both on the 
output voltage on both would drop way down,  and my scope showed me some 
seriously bad oscillations going on.  I suppose these days I know a bit more 
about how to treat those 3-terminal regulators,  but I've never bothered to 
modify the thing...

Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

More information about the cctech mailing list