Dragon32 Power-Supply

[Jules Richardson]

On Wed, 2004-11-24 at 12:52 +0000, John Honniball wrote:
> Jules Richardson wrote:
> > 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.

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.

> 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