From: phkahler@vela.acs.oakland.edu (Paul H. Kahler) Newsgroups: rec.games.video.arcade.collecting Subject: Nintendo Color Inversion (analog) Date: 22 Jul 94 17:02:42 GMT Keywords: Nintendo Color Invert Nintendo Color Inversion Circuit by Paul Kahler -------------------------------------------------------------------------- This circuit is used to invert the color signals from old nintendo games so they may be used with standard (ie not Nintendo) monitors. One of these must be constructed for each of the RGB signals. The only drawback is that it requires a -12V supply (my cabinet has that anyway). +-----XXXXX---------+ | | | |\ +-- +12V | | | \ | | Input -----XXXXX------+-----|- \ | | | \______|_______ Output -5V -----XXXXX------+ +--|+ / | | /| | | / | | +-- -12V GND I used a high frequency LM318 op-amp. The XXXXX are resistors all of the SAME value. 100K is too large and you'll get a lot of noise, while 1K is too much load for the nintendo outputs (the screen won't go completely black). I used 10K for everything and got a really sharp picture. The pinout for the LM318 is: 1 Comp/bal 8 Comp 2 -in 7 V+ 3 +in 6 output 4 V- 5 Comp/bal You don't need to worry about the Comp pins. An LF356 might also work, but I haven't tried it (don't even think of a 741 :)