I have thought about this problem alot.  I never did come up with a solution,
but perhaps some notes would not be totally wasted.

Switch mode power converters attracted my attention.  They are between 80 and
95% efficient.  That PC power supply is a switch mode converter.  I learned it
would take a good bit of engineering to produce a 12VDC-in PC power supply but
that it could be done.  Modern inverters are of a switch mode type, and are
highly efficient, as well as cheap.  However, you will still take some losses
in the power supply step.

Enough solar panels to run an old 286 for a couple of hours a day will cost
probably as much as a used laptop.

I ran a Toshiba 1850C on mostly solar power, and modified an HP portable
deskjet printer to run on the same battery.  A 100 Amp-Hour 12V deep cycle
battery was taken to town and charged, and trickle charged by two 10 Watt
solar panels (one of them broken).  I could run the notebook computer for 3
weeks, for between 6 and 12 hours a day.  The printer was wired from the 12VDC
through a linear voltage regulator providing 7 volts to the 6V internal
battery leads of the printer---the printer went into sleep mode after 1 minute
of inactivity (but only when it thought it was running on internal battery
power), and could be left connected all the time.

The economics of running a computer in the conditions you describe are
prohibitive---an old notebook couild run on one 50 Watt panel with ease, while
an old 286 would probably require several panels.

That being said, I'd still like to put together a 12V-in power supply.  (They
are actually commercially available from at least one solar power equipment
company, together with 12V monitor, printer, etc.---I'm not up to date on
that, however I could perhaps find such a company, or so could you on the WWW).

Alan Davis (who knows little of which he speaks)

> > in this village (or the majority). I need to think about how to
> > interface an older
> > IBM 286, which has a 200W power supply and a VGA monitor with the 12 V
> > source that would be available from a car battery or possibly a
> > solar panel. I
> > understand that laptop parts are more expensive, and there is no
> > AC source to
> > charge those batteries. I would like to adapt existing parts on
> > the IBM, if
> > possible.
--
Alan E. Davis                       Marianas High School (Science Department)
AAA196, Box 10001    [log in to unmask]   http://www.saipan.netpci.com/~adavis
Saipan, MP  96950    15.16oN 145.7oE    GMT+10       Northern Mariana Islands