Commodore 64 Power Supply

[Eric Smith]

I wote:
> Why does it require isolation between the 9VAC and the +5V DC?  It's not
> obvious to me from the schematic.

Roy wrote:
> The 9VAC supply is fed into a voltage doubler to derive the regulated +12V
> and a separate +5VDC supply,  and I don't think that either of those 9VAC
> lines can be grounded.

Neither side needs to be grounded.

The C64 *already* has a bridge rectifier and 5V linear regulator powered
by the 9VAC input to produce an auxiliary 5V supply, so I don't see why
building an external power supply using a transformer with a single 9VAC
secondary, and a bridge rectifier and 5V regulator (linear or switching)
would be a problem.

However, I haven't tried it, and don't accept any responsibility for
anyone else trying it.

Eric