Re: Power Supplies

[ferdimh@gmx.de]

I replaced a Apple //e power supply with a linear power supply which
uses the case bottom as a heat sink. This is way smaller than a new
power switching power supply. There is now enough space for a 3.5''
hard disk or floppy where the power supply was. Though it's quite
efficient, my design has a severe disadvantage: There is no overload
protection other than a fuse (which is fairly slow).

You can simply add a switch to an ATX power supply by connecting it
between the /PSON line(usually green) and ground. If you have an apple
with the video ROM switch below the keyboard and don't need it, it can
be abused for this purpose. And all ATX power supplies made before
2005 do have the the -5V power. Many still have them today.
Because the Apple is not a heavy load the fan can be removed. But I
still have no idea how to fit a AT/ATX into the Apple ][ case.

I also have to note that the original Apple power supply outputs VERY
stable voltages which are usually only achieved by linear power
supplies.  I don't expect that they're needed, but who knows...

----
Ferdinand