Date   : Fri, 19 May 2006 00:24:10 +0100
From   : Philip Pemberton <philpem@...>
Subject: Re: RAF Beeb?

In message <1147956182705.kris@...>
          "Kris Adcock" <kris@...> wrote:

> Are those 'luggable' cases available in a DIY-enthusiasts form, from th
e
> likes of Farnell or RS?

Not to my knowledge, but you could knock something together fairly easily
 out
of the raw components. A few aluminium L-strips for the inner structure,
some
aluminium sheet (Metal Supermarkets were selling 50x50cm sheets of 1mm th
ick
alu for £10+VAT last time I checked) for the main structure, and either
plastic or alu front panels.

Find a knackered Atom or Electron and nick the case and keyboard, then bo
lt
on some hardware to convert the key pulses into a serial link and back ag
ain.

Add a few coats of car body paint and you've got a Beeb luggable!

As far as batteries go, I'd be tempted to use a lithium ion laptop pack,
but
they're rather nasty if mistreated ("vent with flame" is the typical fail
ure
mode). A 6AH sealed lead-acid would probably be safer, but put an inline
fuse
as close to the terminal as you can get it. Just remember - a car battery
 is
a scaled-up SLA, and those things can throw out a good few hundred amps.
Insulated connectors all round, heatshrink over exposed metal, and a fuse
rated just above the maximum current consumption of the entire device.

Because let's face it, it's no fun to have N hours of work go up in flame
s,
just because you were too cheap to fit a fuse in the battery wiring..

:)

-- 
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