Thursday, October 3, 2013

PAL vs. NTSC vs. ME

Well - it's a long story and it started a few moth ago when my chiptune bro 9-heart used a device called VBLANK M1 for making visuals at a gig we booth played. Some day's later I thought that could be a nice toy for my shows as well! Then I remembered my  Sega Game Gear with the broken screen which would give that device a nice housing and if I find a small TFT-display, I may use it for the monitoring of it's visuals.
So I ordered the VBLANK M1 and a I also found a perfect fitting TFT at adafruit.

The Game Gear provides a lot of space

The VBLANK is basically a PCB with a microcontroller and a few passive elements. It has a cinch with video composite output and a jack-socket for the audio-input, which is used to trigger the 8bit-style video effects programmed into the controller. It has two wires for power supply and two LEDs. One is the power-LED and the other is blinking if the audio on the input is loud enough. I planed to put the VBLANK and the TFT into my Game Gear and drill holes for the I/O's into it's housing. When I received the VBLANK and the TFT, the trouble starts. The TFT worked well with my DVD-player, but not with the VBLANK. After asking the VBLANK-developer I found out, that the VBLANK is a NTSC device *umpf*. After that short shock I also found out, that the TFT is compatible to PAL _and_ NTSC. So I asked at adafruit and they confirmed the compatibility to NTSC. They also suggest to return the TFT, but I didn't want to give up that fast and decided to test the VBLANK first with my projector. On my projector it works, but looks a bit strange and not exactly like it should. Btw - this is what my projector shows, when I connect the VBLANK: 15,3 kHz, 60 Hz ,720 x 480i.

I found out that there are some PAL/NTSC converters on the market for cheap so I ordered this one. The converter didn't worked as I expected it *grmpf*. You can just see some stills in an interval of a second. Very unsatisfied but enough for the video-monitoring in the Game Gear. The converter is also small enough to fit into the housing, if everything else is removed. After disassembling the Game Gear, I also noticed that I can reuse the power-supply unit, which provide 6V for the converter and 9V for VBLANK and the TFT. It also has 38V(!) because the original backlight of the Gamegear was a neon-lamp!
Game Gear neon light and a mirror to bundle the light

Because the TFT supports two composite inputs, I added an additional composite to the Geam Gear, so I also can use it to monitor external video-sources. An additional switch can disconnect the VBLANK from the TFT if the output-level maybe make problems some day to drive two video-sinks. You never know...
All in all a dirty hack, but hey: You can use the whole system also battery-powered! =)

Video monitoring of external sources via composite

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