While other video converters have all-in-one chipsets that are much harder to work with, [LoFi Future] explains that the separate EM636165TS DRAM chip on the GBS-8100 provides an ideal spot to tap in and wreak some technicolor havoc. By mapping out the pins and studying how the video output is corrupted by grounding them out or connecting them to each other, he’s been able to come up with fairly repeatable “recipes” for different effects.
In the most basic form, once you’ve soldered the pins of the DRAM chip up to the plug board interface, you’d technically be done. But [LoFi Future] takes it a step further and pairs the GBS-8100 with a separate composite to VGA converter. This provides some additional effects in the form of feedback loops and hue adjustment, but more practically, allows the device to handle composite on both the input and output. It’s a lot of hardware to cram into the enclosure, but thanks to little touches like the printed panel graphics, the final product does looks very professional.
[Russell Kramer] made our day today. We’re tremendous fans of minimalism in electronics design, dirty noise hacks, and that old NES light gun. He’s posted up a project that combines all three to make a light-gun controlled, VGA video display that makes bleepy-bloopy noises to boot. Check out the video below!
To appreciate this hack, you really need to read through the project logs in detail. Start with the VGA signal creation, for instance. The easiest way to go these days is to throw a microcontroller at the problem. But because he’s done that to death, [Russell] takes a step back thirty years and generates the sync pulses periodically with a relaxation oscillator and a binary counter IC. The rest of the build follows this aesthetic choice: everything is op amps and CMOS logic. The rainbow effect, for instance, is created from the audio signal through a three-stage, 120-degree phase-shift oscillator sent to the R, G, and B channels. Kudos!
The high-level overview is that the light intensity and position hitting the gun’s sensor is converted into a voltage that drives an audio-frequency oscillator. This audio output is then piped back into the video generator. Watching the video, it’s obvious that pointing the gun at different parts of the screen changes the pitch, but playing a given pitch is nearly impossible on this thing with all the feedback going on. [Russell] added a bit of more control into the system — when the gun’s trigger is pulled, it registers full-brightness regardless of the video input — but even so, we’d be hard-pressed to play “Mary Had a Little Lamb”.
But that’s not the point. The point is awesome, light-gun-waving noisy madness set to a responsive colorful video background. And that’s been achieved in spades!