BUILD YOUR OWN 2600 JOYSTICK ADAPTER
Materials needed
* (1) 4069 (Hex Inverter)
* (1) 4066 (Quad analog switch)
* (2) PNP 3906 transistor or similiar
* (2) silicon diodes
* (4) 4.7 kohm resistor
* (2) 10 kohm resistor
* (2) 250 kohm resistor \ Values of these resistors are critical.
* (2) 500 kohm resistor / Get as close as you can by stacking.
Don't trust the stripes on those resistors;
take the time to actually measure them.
* (1) 9-pin male Dsub connector (for 2600 joystick connection)
* (1) 15-pin female Dsub connector (for 5200 port connection)
Schematic
5200 port 2600 stick
pin func pin func
--------- ----------
12 +5V---------------------+--7 +5V (2600 sticks)
`--5 +5V (Sega sticks)
15 Ground---------------------8 Ground
13 Bottom Fire----------------6 Fire (2600 fire, or Sega B button)
14 Top Fire-------------------9 Fire (Sega C button)
10K
10 Hpot___/\/\_
\ 1K
PNP \|___/\/\_____3 West
3906 ^| |
9 Pot ________/ |
Common |
4.7K |
12 +5V-------/\/\----------+
10K
11 Vpot___/\/\_
\ 1K
PNP \|___/\/\_____1 North
3906 ^| |
9 Pot ________/ |
Common |
4.7K |
12 +5V-------/\/\----------+
4.7K
12 +5V----+--/\/\---+---------4 East
| 4.7K |
`--/\/\---|--+------2 South
| |
| | _________
| +------------|1 \/ 14|--+5V
| | | |
| | +---------|2 13|
| | | | |
+--|--|---------|3 12|
| | | | |
| | | +------|4 4069 11|
| | | | | |
| | | | |5 10|
| | | | | |
| | | | |6 9|
| | | | | |
| | | | GND--|7_______8|
| | | |
| | | |
| | | `---------------------------+
| | `---------------------------+ |
| | | |
9 Pot | | 500K _________ | |
Common-----------|--|--+---/\/\--|1 \/ 14|--+5V | |
diode | | | | | | |
10 H-Pot---|<-------|--|--|------+--|2 13|-------' |
diode | | | | | | |
11 V-Pot---|<----+ | | | `--|3 12|----------'
| | | | 250K | | 500K
| | | +---/\/\--|4 4066 11|--/\/\--+
| | | | | | |
| | `--|---------|5 10|--+-----|--+
| | | | | | | |
| `-----|---------|6 9|--' | |
| | | | 250K | |
| | GND--|7_______8|--/\/\--+ |
| | | |
| `----------------------------' |
`----------------------------------------'
Notice there are four unused inputs on the 4069. These could
potentially be used for other things, like a rapid-fire circuit.
If you're not going to use them, tie the inputs (pins 5, 9, 11,
and 13) to ground.
Function
* Pushing east on the stick grounds the horizontal circuit, mimicking
the effect of infinite resistance between pot common and H-pot.
* Pushing west causes a short circuit between pot common and H-pot,
i.e. zero resistance.
* The fire button works exactly like it does on the regular 5200
controller.
* If you're using a Genesis controller, button B functions as the
bottom fire button, and button C as the top.
Good Things
* No more problems with games that were unplayable with your non-
centering 5200 sticks.
* Cheap! It only costs about eleven dollars on the raw materials for
one of these, including some rather fancy touches (Y-adapter,
switchable analog stick, etc.)
* It should work with every 2600 joystick there is. I've tested it
with my mechanical switch sticks, my Genesis-to-7800 pad, my
NES-to-7800 pad, and my 2600 remote control joysticks, and they all
work peachy keen.
Bad Things
* 2600 sticks don't have two fire buttons. If you want, you can glue
an extra fire button onto your 2600-compatible stick of choice.
Just wire it up between port pins 14 and 15.
* Won't work with games that require the analog capabilities of the
5200 stick, like Missile Command. A few other games like Galaxian
and Centipede make limited use of the analog-osity of the regular
stick by giving two movement speeds depending on how far you push
the stick. With the adapter, you can only get the fastest speed.
It's not a huge handicap, but it's probably worth mentioning.
* Neither this adapter nor the Masterplay Interface gets along well
with three particular games: Qix, Vanguard and Ms.Pac-Man. There
are others, but I haven't gotten around to trying it on all the
games yet. They will respond to pushing east (or south) on the
stick as if you're pushing west (or north). No real clue exactly
why this happens, but you may be able to make them work by starting
up a game, thrashing the digital stick around until the game
behaves itself, then starting a new game. It might work for you,
and it might not. YMMV.