30 Jun
2008
30 Jun
'08
5:52 p.m.
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