Modifying a CRT television for use as an arcade monitor

Finding himself in need of an arcade monitor [Eric Wright] turned to this ancient CRT television. The problem is that arcade monitors and televisions didn’t operate in the same way, differing in both resolution and refresh rate. [Eric] modified the television to work like an arcade monitor, but only with limited success. He’s hoping a few more alterations will lead him to a complete solution.

The image above shows him testing a Pac-Man machine on the altered Sharp television. Those familiar with the game will immediately notice that there is something wrong. We see most of the tracks upon which Pac-Man and the ghosts travel, but he maze itself is completely missing. To get to this point [Eric] consulted the television and arcade schematics to figure out how to connect the composite sync and three color channels directly to the arcade machine. This way the CRT timing is forced to conform to the game standard. The problem is that there is no way to adjust the drive and cutoff of the individual color channels. This is something [Eric] hopes to fix in the next iteration of his experiments.

If you already have a working arcade monitor but no gaming cabinet why not use a Raspberry Pi?

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Scavenged tube television makes a nice fish tank

aquarium-from-junked-television-set

[McCaulsey] found an old TV waiting for garbage pick-up on the side of the curb. He brought it home and gave it a new life as an aquarium.

His technique is a little rough, but the finished look is exactly what he was going for. He picked up the cheapest aquarium set he could find at the pet store. It just happens to have a curved front to it which helps to recreate the look of the original CRT. After removing most of the electrical components he went to work on the plastic fins that were used to mount them. Having somehow misplaced his Dremel tool the work was done with a drill and a 1/4″ paddle bit.

Once the demolition was over he started the rebuild by placing a backer in the tank. This is an underwater image that will save him from having to look at the inside of the TV case through the water. A piece of Styrofoam was used as a base to properly frame the front of the tank. The only thing we can’t tell from the build album is how he will manage to feed the fish without taking everything apart again.

[via Reddit]

Simulating CRT or Vector displays for more realistic emulation

simulated-crt-monitor-for-emulatorsScaled down it’s not as obvious that this image isn’t a crystal clear rendering of Mortal Kombat gameplay. But we’ve linked it to the full size version (just click on the image) so that you can get a better look. Notice the scan lines? This is the result of an effort to more accurately mimic the original hardware displays used in classic games. [Jason Scott] takes a look at the initiative by describing what he thinks is missing with the picture perfect quality of modern emulators.

One such effort is being mounted for MAME (Multiple Arcade Machine Emulator). There is a series of filters available — each with their own collection of settings — that will make your modern LCD display look like it’s a run-of-the-mill CRT. This is a novelty if you’re a casual gamer who dusts off the coin-op favorites twice a year. But if you’re building a standalone game cabinet this may be a suitable alternative to sourcing a working display that’s already decades old.

An introduction to vector displays

clock

Unlike the CRTs found in big old televisions, vector displays are a bit of a historical oddity. Instead of sweeping an electron beam across the screen from left to right and top to bottom, a vector display draws lines between two points on a screen. Once used in arcade games such as AsteroidsTempest, and old FAA displays, vector monitors have fallen out of favor due to either the complexity or difficulty in acquiring the needed CRT. The folks over at NYC Resistor put up a great tutorial for getting a vector display up and running, and even managed to put a clock on an oscilloscope.

The key component of getting a vector display to work is the digital to analog converter. This DAC takes voltages from eight pins on a Teensy 2.0 dev board and converts them to a voltage anywhere in between 0 and 5 Volts. After connecting the output of this DAC to an input on an oscilloscope, the microcontroller can draw a line between any two points on an axis.

In the video after the break, you can see two of these DACs connected to an oscilloscope displaying a clock. It’s a very cool piece of work, and something that finally gives a purpose to the ancient CRT oscilloscope you might have lying around.

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Demystifying camcorder CRT viewfinders

Every smartphone (and most dumb phones) has a video camera built into it these days. Some of them are even capable of recording respectable HD video. So we’d bet that the decades old camcorder you’ve got kicking around isn’t getting any use at all anymore. [John] wants to encourage you to hack that hardware. He published a post showing just how easy it is to salvage and use a camcorder CRT.

The gist is that you simply need to hook up power and feed it video. The board that is attached to the CRT has its own voltage hardware to drive the tube. He demonstrates a 9V battery as a power supply, but also mentions that it should be pretty easy to power the thing from a USB port. As for video, all it takes is a composite signal. Of course you’ve got to determine the pinout for your particular CRT module. The method he chose was to use a continuity tester to find the path from a capacitor’s negative leg to the appropriate pin header. Next he used a bench supply to inject a current-limited low voltage until he saw response when probing the pins. Finding the composite-in is a similar trial and error process.

So what can you use this for? Why not make it the display for a simple video game?

More CRT fun with the Scope Clock

That’s a sexy way to use parts from an old oscilloscope. [Aaron] took his inspiration from another project that was using CRTs from old oscilloscopes. Now he’s giving back with a site dedicated to sharing information about the Scope Clock. This project is along the same lines as the one we saw a few days ago.

The image above shows his first build in its new home in Hong Kong. The clock is housed in two clear acrylic containers, paired through a surprisingly beefy military grade connector. You can see the journey that it took to get to this polished finish by going to the Prototype tab at the top of the page linked above. One of the images shows some fast captures of the screen redraw. It lets you see the vectors which are being traced on the phosphor screen by the electron gun. This gives an image that we think is far more pleasing than the row scanning of a traditional CRT monitor.

Of course you don’t have a to start from scratch either. Here’s a clock project that just augments a functional CRT scope.

Custom circuit drives a small round CRT display

[Svofski’s] latest hack seeks to do no more than look cool on his desk. We’d say mission accomplished. He doesn’t even need anyone around to be proud of the small round CRT display unit he put together. Just having it hum away next to him will be more than enough to keep him going when regular work gets a bit tedious.

One of the biggest challenges when working with a cathode ray tube is the supply. He compares the requirements with that of Nixie tubes, and this is quite a bit more challenging since he wants to generate the 750V from a 12V DC source. To pull it off he hand wound his own transformer. There are two secondary coils, one for the cathode heater and the other as the supply. You can see a brief clip of the unit in action after the break.

Take note of the PCB section of his writeup. He took a meandering route through several different software packages before printing the board. It started with Eagle, moved to freerouting.net, which produced a Specctra file that he converted to gEDA using a Python script.

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