A Lightgun For LCDs – Thanks To Maths!

June 28, 2018 by Lewin Day 47 Comments

Light guns were a fun way to learn to shoot things on consoles, enjoying their heyday in the 80s and 90s. The original designs largely relied on the unique characteristics of CRT televisions and the timing involved in the drawing of their frames. Unfortunately, due to a variety of reasons (dependent on the exact techniques used), they typically do not work at all with modern LCD & plasma screens.

The light gun contains a camera, and reportedly works by using the distortion of the rectangular image of the screen to calculate the position of the light gun itself.

Recently, there has emerged a new project called the Sinden Lightgun. In the How It Works video, it seems to use a fairly standard 30fps camera inside the gun to image the television screen being used by the game. The display is then rendered in 4:3, letterboxed on a 16:9 aspect ratio display, within a rectangular bezel. The image from the camera is then processed, and the distortion of the game image is used to calculate the position of the gun and the direction of its aim. Processing is handled by the host computer running MAME and the requisite coordinates are fed back in to the game code.

The basic concept seems sound, though as always, there’s a healthy amount of skepticism around the project. We’d love to hear your take, on whether the concept is plausible, and whether the lag figures stated are cromulent. We’re always excited to see new developments in the lightgun space! Video after the break.

Our own [Will Sweatman] penned an excellent piece on a variety of ways one could resurrect the venerable game of Duck Hunt, too.
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Tricking Duck Hunt To See A Modern LCD TV As CRT

August 30, 2016 by Jenny List 47 Comments

A must-have peripheral for games consoles of the 1980s and 1990s was the light gun. A lens and photo cell mounted in a gun-like plastic case, the console could calculate where on the screen it was pointing when its trigger was pressed by flashing the screen white and sensing the timing at which the on-screen flying spot triggered the photo cell.

Unfortunately light gun games hail from the era of CRT TVs, they do not work with modern LCDs as my colleague [Will Sweatman] eloquently illustrated late last year. Whereas a CRT displayed the dot on its screen in perfect synchronization with the console output, an LCD captures a whole frame, processes it and displays it in one go. All timing is lost, and the console can no longer sense position.

[Charlie] has attacked this problem with some more recent technology and a bit of lateral thinking, and has successfully brought light gun games back to life. He senses where the gun is pointing using a Wiimote with its sensor bar on top of the TV through a Raspberry Pi, and feeds the positional information to an Arduino. He then takes the video signal from the console and strips out its sync pulses which also go to the Arduino. Knowing both position and timing, the Arduino can then flash a white LED stuck to the end of the light gun barrel at the exact moment that part of the CRT would have been lit up, and as far as the game is concerned it has received the input it is expecting.

He explains the timing problem and his solution in the video below the break. He then shows us gameplay on a wide variety of consoles from the era using the device. More information and his code can be found on his GitHub repository.

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NES Light Gun Turned (Video) Synthesizer

February 25, 2016 by Elliot Williams 7 Comments

[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!

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Nintendo Light Gun Retrofit Lets It Play Color-based Games

October 2, 2012 by Mike Szczys 4 Comments

This Nintendo light gun, aka Zapper, looks like a stock device. But a peek inside shows that the circuit board has been replaced. [CNLohr] added USB functionality and a few extra sensors that let him write his own games for that use the classic controller.

After cracking open the case he measured the shape of the circuit board so that he could recreate it exactly. This let him design his own board that would drop right into the same plastic support pieces as the original. His circuit uses an ATmega8u2 to provide a USB connection and read the attached sensors. One interesting aspect is the group of four long traces that act as an expandable i2c bus. [CNLohr] went with this so that he could use daughter boards to add in sensors later. In the demonstration seen after the video he’s using a photodiode as a color sensor. It allowed him to write the color-based game seen above where you shoot a different color of target in each round.

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NES Light Gun Gets A Burning Laser Upgrade

September 21, 2012 by Mike Szczys 34 Comments

The Nintendo Light Gun makes a perfect burning laser. Of course it’s been gutted to make this happen. Nonetheless, the retro look can’t be beat, and the gun form factor is just what you need in a laser weapon.

This will literally burn your eye out of your head, so [Justin] and his buddies over a North Street Labs are all wearing protective goggles designed for this laser’s wavelength. But they also built a safety into the zapper itself. At the beginning of the video clip (embedded after the break) you will see there’s a key lock mounted in the butt. This lock completes the circuit between the battery and driver board. The 2W output is achieved by a 445nm M140 diode. A lot went into the heat sink and mounting cylinder to make sure the diode doesn’t just burn up after a few seconds of use.

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