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MiniSport Laptop Hacker 24
MiniSport Laptop Hacker (TM) - Vol #24. November 1994
To discourage pecuniary interests, Copyright (c) 1994 Brian Mork
>>> ADMIN
The MLHacker (TM) series is sized to print out on the front and back of
a single 8.5"x11" sheet of paper, using 8lpi. You or your print program
have to add your own page break lines or form feed character. Back
issues are available from ftp.cs.buffalo.edu in the \pub\msdos\ham-radio
directory, or on SimTel archives (e.g. oak.oakland.edu in the
\pub\msdos\packet\mlhacker.zip file).
>>> MOBILE BATTERY POWER -- CONTINUED
Last issue, I included part one of Jim Harvey's description of how he
made a suitable container for the custom battery pack. Here's the
second and last part. Next issue I'll include his description of making
a custom battery charger.
"Now solder the two brass contacts to the prepared PC board header.
Support the PC board on a small piece of wood, copper side up. Tin the
board where the contacts will lie, then place the prepared brass
contacts on the board. Heat, and flow solder between the contact and
board but don't let it run down the stem of the "T". Check the spacing
and angle of your contacts on the battery. You can bend the brass to
fit or reheat the assembly and move the contact a little. You want a
firm, flat contact with the battery terminals when the header is aligned
squarely on the top.
PC Board Header Top View With Battery Contacts Attached
Notch for battery contact
|
----------- v -----------
Asterisks indicate / |*****| \
position of contact / ************* \
/ ************* \
Insulating Cut --> |===================================|
on Centerline \ ************* /
\ ************* /
\ |*****| /
----------- ^ -----------
|
Notch for battery contact
Side Edge View of PC Header Showing Contact Position
(Foil side) *************
|===============*****===============|
(Bare side) *****
***** Battery fits
***** here
*****
"Solder your power cable to the two halves of the header assembly. Use
red and black wire to keep track of polarity. You MUST use an in-line
fuse holder close to the battery pack with about a 5 amp fuse.
Terminate the loose end of the cable with your power connector of choice
and the contact header assembly is finished.
"The next step is to wrap the header and the top 2 1/2 inches of the
battery pack with insulating fiberglass. Inexpensive auto repair resins
set up quickly, so you must have all material cut in advance.
"Prepare a piece of fiberglass to cover the top of the battery by
cutting a 2" by 3" piece of cloth and unraveling about 3/8 inch on each
of the four edges. This will allow the material to fold down over the
sides of the battery without wrinkling. Next, cut a 2 1/2" by 6 1/2
inch rectangular piece, which will wrap around the body of the battery.
Cut two small 2 1/2" by 1/2" strips. These will help form a channel
around the molded battery keyway, necessary to ensure later that the cap
is slipped on with the proper polarity.
"Open the Condom and starting at the contact end, unroll it down over
the whole battery. This will protect the battery from the fiberglass
resin. Slip the completed contact assembly into working position on the
battery over the Condom, taking care not to tear the latex. Now put a
bit of half inch wide masking or electrical tape over the brass
contacts, carefully sealing the tape to the latex on the sides and up
over the top about 1/8 of an inch. You do not want the Epoxy to bind to
the contacts in the fiberglass shell, they must be free to move a bit.
Be sure to observe polarity of your cable at this time, it's easy to
plug the header on backwards.
"Wrap string closely around the battery about 2 1/2 inches down from the
top. This will form a reinforcing ridge at the bottom edge of the
completed shell. Tuck the loose ends under, or tie an inconspicuous
knot.
"You are ready to begin the messy fiberglass process. Spread newspapers
around everywhere, this stuff is permanent. You should wear old
clothes, rubber gloves and eye protection.
"Mix about an ounce and a half of Epoxy resin per the manufacturers
directions. If you have a 3 or 5 ounce Dixie cup, it's easy to guess
the amount. Remember, this type of Epoxy sets up in just a few minutes
so it is important to plan and to have all the pieces of cloth prepared.
"Paint a thick coat of Epoxy on top of the contact assembly and around
the edges. Place the unraveled 2" x 3" glass cloth on top and paint
more liquid on the cloth until it is saturated. Brush the unraveled
edges down over the sides of the battery. Now apply Epoxy all the way
down to the string and position the two narrow 2 1/2" x 1/2" strips on
either side of the molded keyway that runs down the side of the battery
case. This helps form a matching keyway in the fiberglass shell.
Saturate these strips with resin, then center the 2 1/2" x 6 1/2" cloth
over the key way and wrap it around the battery. The bottom edge should
cover the string and the top edge should overlap the top of the contact
assembly slightly. Flow resin over all the cloth until it is saturated
and smooth it out with the brush. Rotate the assembly frequently to help
keep the fluid from dripping.
"In about five minutes you will feel the brush start to drag. Continue
to rotate the battery slowly to prevent drips until the resin has become
stiff. Set the assembly aside for 4 hours or so to set up. When it is
solid to the touch, you can gently pull the cap and Condom from the
battery. The Condom will separate from the fiberglass with gentle
tugging. Let the shell harden a few more hours and if there is still a
sticky residue on the inside, wipe it out with a rag and lacquer
thinner. Cut and sand the bottom edge even at the string and sand any
rough edges on the fiberglass. Dimples, bubbles or ragged edges can be
touched up with 5 minute Epoxy cement.
"Paint the finished shell if you desire, and you're done. I also
constructed a couple of contactless fiberglass caps to protect my spare
batteries from shorting out inside my tool box.
>>> EXTERNAL CGA MONITOR -- WITH COLOR!
I found a source for Minisport external screens. As you're probably
aware, the Minisport has the internal logic to drive a Color Graphics
Adapter (CGA) monitor. The built-in screen, of course, is monochrome,
but there's a plug on the back to hook up an external, full-color
screen. Wouldn't it be great to tap into this potential at minimal
cost?
Here's what I found: A 5" color monitor, *not* enclosed in any case
(you'll have to put it in a metal or wood box). From the picture, you
get a tube and the electronics board mounted in a minimal frame
arrangement. It runs off from 12 VDC and uses a standard interface
connector. They cost $69 plus $5 s/h. Advertisements show up in the
magazine _Midnight Engineering_.
The small size and mandatory custom enclosure could make for some
interesting portable setups for use with the Minisport! They're
available through Timeline Inc., 23605 Telo Ave,, Torrance, CA 90505.
Technical info line is 310-784-5488. Orders only line is 800-223-9977.
I have not purchased one of these, and I've not dealt with the retailer.
I'm bringing it up here only to make known the availability of such a
beasty. If you purchase one and use it with the Minisport, let me know!
Please provide feedback! * Direct data 1-509-244-9260
* ARO Net KA9SNF@ka7fvv.#ewa.wa.usa
* Internet bmork@opus-ovh.spk.wa.us
73, Brian * 6006-B Eaker, Fairchild, WA 99011
