From linley@netcom.com Fri Dec 2 01:03:14 1994
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Date: Fri, 2 Dec 1994 01:03:52 -0800
From: linley@netcom.com (Bruce James Robert Linley)
Message-Id: <199412020903.BAA15787@netcom17.netcom.com>
To: gchance@ecst.csuchico.edu
Subject: Update on 5200 switchbox plans for WWW archive
Cc: linley@netcom.com
Status: RO
Greetings. I am sending you an updated copy of my plans for constructing
the RF/power box for the 5200. Some people have complained to me that part of
the instructions are missing and I have traced this to the fact that some
www browsers choke on lines of text that start with or contain a pipe (|)
character. This resulted in plans without the diagram and with the key
portions of the instructions (which were next to the diagram) missing.
Other minor tweeks have been made as well. Thanks.
#include <ftp.netcom.com:/pub/li/linley/at-5200-switchbox.txt>
Where do I hook up the power supply to my 4 port Atari 5200?!
The early Atari 5200s came with an unusual switchbox which supplied power to
the 5200 down the same wire the 5200 uses to send the video signal to your TV.
The power supply plugged into the switchbox. Unfortunately, these switchboxes
seem to have gotten lost over the years and are difficult to come by. Newer
5200s (the one with only two controller ports) had the power supply jack on
the console itself. Fortunately, it is not difficult to construct your own
RF/power supply box for the 5200. There is one difference, though. The
original 5200 switchbox would automatically switch from your TV antenna/cable
to the 5200 when you turned the console on. (This is probably the only reason
why you would want power going into the switchbox.) With the RF/power box
described below, you will need to use a standard game/tv switchbox to
accomplish this function.
What do I need to build the RF/Power box?
The following parts are needed to construct the box. Where applicable, Radio
Shack part numbers, and prices, have been provided. You may use another RCA
jack in place of the F jack if you wish. I chose to use the F jack to avoid
ever accidentally plugging the 5200 and TV cables in backwards, which would
result in 11.5 volts DC going into your TV set, possibly damaging it. You
can also wind your own choke (inductor) if you wish.
RS# Part Price
-------- ---------------------------- -----
270-235 2"x2.75"x1.625" Aluminum Box $1.99
274-1563 Coaxial DC power jack $1.79
278-212 Cable TV type F jack (2 pack) $0.99 (optional, see above)
274-346 RCA type phono jack (4 pack) $2.49
272-131 0.01 uF Ceramic Disc capacitor (2 pack) $0.59
273-102 100 uH 2A Choke (inductor) $0.99
Total $8.84 + local tax
And of course, you'll need a soldering iron or gun and some solder.
How do I build it?
Drill holes in the aluminum box for each jack to match the diagram below.
The box itself forms the common ground connection to all three jacks. To
reduce signal loss and ensure the common ground, I recommend using chrome
or gold plated type jacks.
F jack (to TV)
__
+-------------I I-------------+
I I__I I<--- Aluminum box
I I I
I \ 0.01uF I Solder the leads of the capacitor to
I \ _ Capacitor the center pins of the F jack and the
I \/@I I RCA jack. Solder the leads of the
I \/ I choke to the center pins of the DC
I \ I power jack and the RCA jack. Screw the
I Choke \ I box shut. You're done. See? That
I ---I/////I---\ I wasn't hard at all was it?
I _L _L I
+------I I----------I I------+
I__I I__I
DC power jack RCA jack
(to pwr supply) (to 5200)
How does it work?
The capacitor transparently passes the video signal from the 5200 to the TV
output jack, while at the same time preventing the DC power from the power
supply jack from going into your TV. The choke (inductor) transparently
passes the the 11.5 volt DC power to the 5200 via the RCA jack while at the
same time preventing the video signal from escaping back down the power supply
wire. The aluminum box itself helps keep the video signal confined to where it
belongs to prevent possible interference and to ensure that as much of the
signal as possible gets to your TV. For this reason, plastic boxes are
discouraged.
Power supply info (if you don't have one).
The 5200 power supply is 11.5 volts DC @ 1.95 amps and has a standard type
coaxial plug (center positive 5mm OD, 2.1mm ID).
Feel free to drop me a line (at the address below) if you have any trouble
or just to let me know how the project went.
--
Reality.............................................. Bruce James Robert Linley
Internet....................... linley@netcom.com (linley1@aol.com if you must)
Postal......................... 3675 S. Rainbow Blvd. #107, Las Vegas, NV 89103
Amateur Radio................................. KE6EQZ (-.- . -.... . --.- --..)