[metal_chimiste]

salut,

si tu es pressé, tu peux commander ça:

http://www.mikesarcade.com/cgi-bin/store...=NININVAMP


Sinon, je peux te faire un montage avec 3 LM318 comme on peut le trouver ici:

http://www.gamearchive.com/Video_Games/F...onfaq.html
... ma page de référence.

RGB polarity
While all raster monitors accept RGB inputs, they can have either positive or negative logic. The majority of games use positive logic (when the voltage is on, the electron gun turns on, and you get a bright image), but Nintendo games use negative logic, which works the other way around.
RGB signals are analog signals; you'll need an analog inverter to get around the problem; a CMOS hex inverter (say, a 4069), which is designed to invert digital signals, won't work. To be more precise, it theoretically *shouldn't* work, but on the practical side, a few people have tried it and actually managed to make it work. Your mileage may vary. One tip: if you try this, make sure you ground all of your unused inputs.

Meanwhile, the "right way" is to use an analog inversion circuit for each of the three RGB signals. It requires a +12V, -12V, and -5V supply, but some power supplies will supply all three voltages. Thanks to Paul Kahler for the original schematic and document (see reference {9.2.2}).



                              R3
                      +-----/\/\/---------+
                      |                  |
                      |    |\  +-- +12V |
            R1        |    |  \ |        |
Input ------/\/\/------+-----|-  \        |
                      |    |LM318 \______|_______ Output
-5V --------/\/\/------+  +--|+    /
            R2          |  |  /|
                          |  | /  |
                          |      +--  -12V
                          GND
     
R1, R2, and R3 are all identical resistors.  A value of roughly
10K should provide good results.  The LM318 is a high-frequency
op-amp.  Its pinouts are as follows:

                      1 Comp/bal    8 Comp
                      2 -in          7 V+
                      3 +in          6 output
                      4 V-          5 Comp/bal

The "Comp" pins may be ignored.  An LF356 might also work, but
the 741 is not recommended.


Sync polarity:
Now that we can generate the RGB signals our monitor requires, we still have to put the signals on the screen in an orderly fashion. The is what the "sync" signals are for.
Again, we run into the problem that some boards produce negative sync, and some don't. Fortunately, since all sync signals are digital, the process is much simpler; using a *really* fast CMOS hex inverter is a perfectly legitimate way around the problem. A TTL inverter should also work; all sync signals generally operate at TTL levels. Still, this is dicey business, so your mileage may still vary.

Suite par mp si tu veux.