High Voltage Monitor Power Supply Conversion

Repurpose An Old CRT Computer Monitor As A High Voltage Science Project Power Supply

June 14, 2014 by Todd Harrison 17 Comments

Finally somebody has found a good use for all those old CRT computer monitors finding their way to the landfills. [Steven Dufresne] from Rimstar.org steps us through a very simple conversion of a CRT computer monitor into a high-voltage power supply. Sure you can make a few small sparks but this conversion is also useful for many science projects. [Steve] uses the monitor power supply to demonstrate powering an ionocraft in his video, a classic science experiment using high voltage.

The conversion is just as simple as you would think. You need to safely discharge the TV tube, cut the cup off the high voltage anode cable and reroute it to a mounting bracket outside the monitor. The system needs to be earth grounded so [Steve] connects up a couple of ground cables. One ground cable for the project and one for a safety discharge rod. It’s really that simple and once wired up to a science project you have 25kV volts at your disposal by simply turning on the monitor. You don’t want to produce a lot of large sparks with this conversion because it will destroy the parts inside the monitor. The 240K Ohm 2 watt resistor [Steve] added will help keep those discharges to a minimum and protect the monitor from being destroyed.

Yes this is dangerous but when you’re working with high-voltage science experiments danger is something you deal with correctly. This isn’t the safest way to get high-voltage but if you have to hack something together for a project this will get you there and [Steve] is quite cautious including warning people of the dangers and how to safely discharge your experiment and the power supply after every use. This isn’t the first high-voltage power supply that [Steve] has constructed; we featured his home-built 30kV power supply in the past, which is a more conventional way to build a HV power supply using a doubler or tripler circuit. Join us after the break to watch the video.

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The Open Hardware Driver For CRTs

June 8, 2014 by Brian Benchoff 23 Comments

driver CRTs are the king of displays for any homebrew project. They have everything – high voltages, high vacuums, X-rays, and the potential for a vector display – that makes a project exude cool. Getting an old CRT up and running, though, that’s another story. Never rear, because now there’s an Open Hardware eletrostatic CRT driver for your next display.

[Eric] designed a driver circuit that should be able to send a picture to most 2″, 3″ and some 5″ electrostatic CRTs, the kind found in ancient TVs and oscilloscopes. The 1kV power supply uses a transformer usually found in a CCFL bulb, and is able to produce several milliamps. You’ll want to keep one hand behind your back when working on this.

The driver circuit takes a 0-3.3V analog signal for deflecting the beam along the X and Y axis. The amplifier has enough bandwidth to handle NTSC video, so displaying video along with vector letters and shapes is also a possibility with this circuit. Most of the files are available on the git, with three boards available to be ordered from OSHPark.
Thanks [Mike] for the tip.

Vector Graphic Flappy Bird Harder Than It Should Be

May 26, 2014 by Mike Szczys 4 Comments

The dark room at Maker Faire was loud, after all it’s where Arc Attack was set up plus several other displays that had music. But if you braved the audio, and managed not to experience a seizure or migraine from all the blinking you were greeted with these sharply glowing vector displays on exhibit at the TubeTime booth. We did the best we could with the camera work, but the sharpness of the lines, and contrast of the phosphorescent images against the black screen still seems to pop more if viewed in person.

This isn’t [Eric’s] first attempt at driving high-voltage tube displays. We previously covered his dekatron kitchen timer. But we’d say he certainly stepped things up several notches in the years between then and now. He blogged about Asteroids, which is running on the same hardware as the Flappy Bird demo from our video above. An STM32F4 Discovery board is running a 6502 emulator to push the game to [Eric’s] CRT vector driver hardware.

Just before we were done at the booth, [Eric] turned to us with a twinkle in his eye. He confessed his delight in purposely leaving out any button debounce from the Flappy Bird demo. As if it wasn’t hard enough it tends to glitch after passing just a few of the pipe gates. Muhuhahaha!

Turning A Tiny CRT Into A Monitor

March 1, 2014 by Brian Benchoff 18 Comments

[GK] picked up a few tiny 2″ CRTs a while back and for the longest time they’ve been sitting in a box somewhere in the lab. The itch to build something with these old tubes has finally been scratched, with a beautiful circuit with Manhattan style construction.

[GK] has a bit of a fetish for old oscilloscopes, and since he’s using an old ‘scope tube, the design was rather simple for him; there aren’t any schematics here, just what he could put together off the top of his head.

Still, some of [GK]’s earlier projects helped him along the way in turning this CRT into a monitor. The high voltage came from a variable output PSU he had originally designed for photomultiplier tubes. Since this is a monochrome display, the chrominance was discarded with an old Sony Y/C module found in a part drawer.

It’s a great piece of work that, in the words of someone we highly respect is, “worth more than a gazillion lame Hackaday posts where someone connected an Arduino to something, or left a breadboard in a supposedly “finished” project.” Love ya, [Mike].

We Salute The Television Tube Flag

February 24, 2014 by Adam Fabio 17 Comments

From [Gijs] comes Beeldbuis Vlag Tijsdlijn, or television tube flag (Translated). We’re not up on our Dutch, but it appears that [Gijs] and friends have created a television tube which waves much like a flag in response to airflow from a fan. The effect is pretty darn amazing, and that’s putting it mildly. To create this hack, [Gijs] built a modified Wobbulator. The Wobbulator is an early video synthesizer which used added steering coils to modify the operation of a standard TV tube. When excited, the coils would deflect the tube’s electron beam, causing some rather trippy images to appear on-screen. (Yes, here at Hackaday “trippy” is a scientific term).

[Gijs] wanted his screen to be “waved” by a fan, just like a flag would wave. To do this he used an anemometer made of ping-pong ball halves. The anemometer spins up a DC motor from a CD-ROM drive. In this application, the motor acts as a generator, creating a DC voltage. An ATmega328 running the Arduino code reads the voltage from the motor. If the anemometer is spinning, the Arduino then outputs a sinusoidal value. The Arduino’s output is amplified and applied to the coil on the CRT. A network of power resistors ensures the amplifier is correctly loaded. The results speak for themselves. In the video after the break, the tube flag is displaying a slide show of photographs of its construction. As an added hack, [Gijs] used an Arduino Leonardo as a USB keyboard. When the anemometer spins, the primary ATmega328 sends a signal to the Leonardo, which then emulates a push of the arrow keys on the host computer. This lets the tube flag advance its own images. Very cool work indeed!

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The 30th Anniversary Macintosh

February 5, 2014 by Brian Benchoff 17 Comments

It’s been just over thirty years since the original Macintosh was released, and [hudson] over at NYC Resistor thought it would be a good time to put some old hardware to use. He had found an all-in-one Mac SE “on the side of a road” a while ago (where exactly are these roads, we wonder), and the recent diamond anniversary for the original mac platform convinced him to do some major hardware hacking.

Inspired by a six-year-old project from a NYC Resistor founder aptly named the 24th anniversary Mac, [hudson] decided to replace the old hardware with more powerful components – in this case, a BeagleBone Black. Unlike the earlier build, though, the original CRT would be salvaged; the analog board on the Mac SE has pins for video, hsync, vsync, and power.

To get a picture on the old CRT, [hudson] needed to write a software video card that used the BeagleBone’s PRU. The CRT isn’t exactly “modern” tech, and everything must be clocked at exactly 60.1 Hz lest the CRT emit a terrible buzzing sound.

With a software video card written for the old CRT, the BeagleBone becomes the new brains of this beige box. It runs all the classic Linux GUI apps including XEyes and XScreenSaver, although flying toasters might be out of the question. He also managed to load up the Hackaday retro site with xterm, making this one of the best ways to make an old Mac SE useful.

Retrotechtacular: Cathode Ray Tube (CRT) Manufacturing

December 10, 2013 by Mike Szczys 21 Comments

This week we return to the grainy and un-color-corrected goodness that is synonymous with ancient video reels. [CNK] sent in a tip to a set of videos showing how Cathode Ray Tubes are manufactured on a massive scale. You’ll want to watch the pair of clips embedded below which total about 18 minutes. But there’s also some background to be found at this post from the Obsolete Technology Telley Web Museum.

The video presentation starts off with a brief overview of the way a color CRT works. It then moves to a factory tour, carefully showing each step in the process. The footage was shot in the 1960’s and because of that we catch a glimpse of some vintage equipment, like that used to measure the curvature of the CRT glass. You may be thinking that the world of CRT is in the past, but not so. We think there may even been a coming fad of producing them in your home lab.

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