[Mobile-Portable] Computers

[Jim Miller]

I can't answer your question BUT, I had a laptop in which the internal
regulator shorted and would not allow external power input, period.   Being
scrap, I cut the internal regulator away from the main board and connected
wires to go to a 12 volt  (13.8v) supply.  It worked just fine.  I am not
recommending this because you do not need it and it disables the batteries
and internal regulator, but the 19v is not needed to RUN the laptop.  It is
needed to charge the batteries which then feed through the internal
regulator to run the laptop.  Bottom line, it likely is not critical at all.
It is a battery charger.  

My recommendation is - You have a 12v supply (battery?) to run your radio
with you.  Take an extra 6 volt supply with.  Connect them in series to
create 18 (13.8 and 6.9 = 20.7v right off the charger but only for a few
minutes) and that will work just fine for you.

For a stationary supply - I don't think I would use a 24v DC supply direct
unless you at least get inside and see if you can adjust it down to
something closer to reasonable.  And put a few dropping diodes in series
with the higher voltage until you drop it to the 19 or 20 volts or put an
LM317 chip regulator (on some sort of small heat sink) on the 24v supply and
set to what you want.  Just adding diodes is the cheapest, easiest, and
fastest (use 1 amp diodes).  24 volts to 19.5 volts = 4.5 volts drop even if
you don't adjust the 24v supply.  Diodes are about .66 volts drop each so
about 7 diodes will do it.

73, Jim KG0KP

-----Original Message-----
From: Mobile-Portable [mailto:mobile-portable-bounces at mailman.qth.net] On
Behalf Of N1KHB--- via Mobile-Portable
Sent: Monday, June 27, 2016 9:15 AM
To: mobile-portable at mailman.qth.net
Cc: N1KHB at aol.com
Subject: [Mobile-Portable] Computers

Hi All,
   In consideration of a suitable external power  source for a laptop while
on portable ops such as portable ham radio, I'm  wondering how accurate the
common 19 volts needs to be for proper operation.  I've already thought
about running the normal power supply from an inverter, but  I'm looking for
alternatives nonetheless and in any case I remain curious about  the voltage
spec. Thanks!
 
Sonny N1KHB
 
 
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