Here is a basic schematic of the mod, as you can see there isn't really much to it. Additional resistors, or resistors of different values may be needed to balance the colors depending on the LEDs used. At this point the mod still needs more testing with different parts before the ideal configuration can be determined. Folklord (who I must thank for keeping me interested in this) is also working on getting this inside an actual PSP, so based on his results we can adjust the schematic accordingly.
...how does it coupe with a video being played? does it change to the dominate colour on screen like the TV example?
Here is a much longer version of the video to demonstrate this. There is a second set of test images displayed, followed by some colorful intro videos which show how it responds to quick changes and varieties of color.
[youtube=425,350]ysaVtJUQXpY[/youtube]
The individual red, green, and blue LEDs are triggered by a logic 1 on the corresponding colors MSB line going to the LCD. This means they will respond to only the brightest pixels (all values > 0x7F) in proportion to how much screen area they fill in a given frame. If there are two bright colors which occupy equal area on the screen, then the LEDs will show a color somewhere between the two.
This can be seen in the second set of test images. As more black appears on screen, the LEDs will dim, and eventually turn off. When the image of bright red, green, and blue in equal amounts is displayed, the LED color is white because all three are combined. When the image of dark red, green, and blue is displayed, the LEDs will turn off because there are no bright colors on screen. If one of the colors bars is made bright then the LEDs will match that color and continue to ignore the other dim color bars (all values < 0xF0).
...And the idea is superb, take the MSB signals straight from the LCD, Amplify them with op amps, and then use them to drive the Positives of Led's with the corresponding colours.
This is exactly how I had tried it it before, but you can see in the new schematic, the transistors work a little different. Each transistor is used to rapidly open and close the circuit for it's respective LED based on the input signal from the LCD. This creates an effect similar to pulse width modulation, which allows the colors to blend in sync with the video.
