23 Nov
2004
23 Nov
'04
11:26 p.m.
On Wed, 2004-11-24 at 12:52 +0000, John Honniball wrote:
Jules Richardson wrote:
Uh huh. I think I've got *one* that still has the regulators and
heatsink intact. I seem to recall that bypassing the regulators was also
a modification when adding the disk pack; the floppy drive unit
contained all the power regulation for itself and the machine, and just
fed regulated 5V DC into the back of the Atom.
In the six or so Atoms that have passed through
my hands though I've
never had one with the original supply, so I can't confirm that :) (All
of mine have either been kits - and I assume the PSU was optional - or
previous owners have bypassed the regulators and used a more capable
supply)
Ah, that was a standard modification. The Atom uses two 7805
regulators in parallel, which is not a good way to turn two
1A regulators into a 2A PSU. In practice, one regulator
(depending on the voltage tolerances of the parts) takes
nearly all the load, while the other regulator just sits
there. So, many Atom users who expanded their machines
also bypassed the regulators and added a proper external
supply. I'll check my boxed Atom in the loft sometime to
see what
brick it's got.
I've got one boxed one, but it came without a PSU. Actually, there
almost didn't appear to be space in the box *for* a PSU, which made me
wonder if those were shipped as a seperate parcel.
I'm still looking for an Atom with a colour board; presumably by the
time the colour board came on the scene everyone was buying BBC micros
so they're somewhat rare (although I do have an Atom with the BBC BASIC
board in it). Would be nice to get my hands on a Prophet sometime too!
cheers
Jules