Hijacking A Sony Watchman For Pong

March 7, 2018 by Inderpreet Singh 11 Comments

The era of the vintage television was a great one, and one of the transitional by-products was the Sony Watchman. It was a portable TV which Sony started selling in 1982, and the amazing thing about it was that it had an actual 4-inch cathode ray tube or CRT. [Sideburn] just posted a video in which he hijacks the internals of a Watchman to make it into a portable game of Pong.

The hack begins with removing the TV tuner module inside to make some room for the new residents. Next comes the M51364P which is VIF video decoder chip, and for which surprisingly there is not a lot of info on the web. They were able to find a part of the schematic, which though it was in Russian may still be useful for enthusiasts. Removing the VIF revealed the audio and video pins that needed the appropriate signals for the hack to be successful. In an age of multilayer boards it is amazing how a two-layer PCB makes life so easier for the tinkerer.

For the new brains an Arduino Nano clone was selected, and instead of adding modern buttons the existing volume and band select switches were convinced to be the paddle control and play/pause button. Getting everything to fit was easy with the absence of the tuner module, and voila! New(ish) hardware. For the firmware, [Sideburn] turns to Hackvision firmware which has a host of games such as Space Invaders, Asteroids, and even Tetris.

We covered Hackvision a few years ago as a hardware/firmware bundle, and if you are more into CRTs then check out the Arduino driven 6845 CRT controller.

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Whatever Happened To The Desktop Computer?

February 16, 2018 by Brian Benchoff 210 Comments

If you buy a computer today, you’re probably going to end up with a laptop. Corporate drones have towers stuffed under their desks. The cool creative types have iMacs littering their open-plan offices. Look around on the online catalogs of any computer manufacturer, and you’ll see there are exactly three styles of computer: laptops, towers, and all-in-ones. A quick perusal of Newegg reveals an immense variety of towers; you can buy an ATX full tower, an ATX mid-tower, micro-ATX towers, and even Mini-ITX towers.

It wasn’t always this way. Nerds of a sufficient vintage will remember the desktop computer. This was, effectively, a tower tilted on its side. You could put your monitor on top, negating the need for a stack of textbooks bringing your desktop up to eye level. The ports, your CD drive, and even your fancy Zip drive were right there in front of you. Now, those days of desktop computers are long gone, and the desktop computer is relegated to history. What happened to the desktop computer, and why is a case specifically designed for a horizontal orientation so hard to find?

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Chasing The Electron Beam At 380,000 FPS

January 29, 2018 by Adam Fabio 20 Comments

Analog TV is dead, but that doesn’t make it any less awesome. [Gavin and Dan], aka The Slow Mo Guys recently posted a video about television screens. Since they have some incredible high-speed cameras at their disposal, we get to see the screens being drawn, both on CRT and more modern LCD televisions.

Now we all know that CRTs draw one pixel at a time, drawing from left to right, top to bottom. You can capture this with a regular still camera at a high shutter speed. The light from a TV screen comes from a phosphor coating painted on the inside of the glass screen. Phosphor glows for some time after it is excited, but how long exactly? [Gavin and Dan’s] high framerate camera let them observe the phosphor staying illuminated for only about 6 lines before it started to fade away. You can see this effect at a relatively mundane 2500 FPS.

Cranking things up to 380,117 FPS, the highest speed ever recorded by the duo, we see even more amazing results. Even at this speed, quite a few “pixels” are drawn each frame. [Gavin] illustrates that by showing how Super Mario’s mustache is drawn in less than one frame of slow-mo footage. You would have to go several times faster to actually freeze the electron beam. We think it’s amazing that such high-speed analog electronics were invented and perfected decades ago.

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Why Sony’s Trinitron Tubes Were The Best

January 3, 2018 by Adam Fabio 56 Comments

If you’re old enough to remember Cathode Ray Tube (CRT) Televisions, you probably remember that Sony sold the top products. Their Trinitron tubes always made the best TVs and Computer Monitors. [Alec Watson] dives into the history of the Sony Trinitron tube.

Sony Color TVs didn’t start with Trinitron — for several years, Sony sold Chromatron tubes. Chromatron tubes used individually charged wires placed just behind the phosphor screen. The tubes worked, but they were expensive and didn’t offer any advantage over common shadow mask tubes. It was clear the company had to innovate, and thanks to some creative engineering, the Trinitron was born.

Closeup of a Trinitron tube shows unbroken vertical stripes which led to a brighter picture.

All color TV’s shoot three electron guns at a phosphor screen. Typical color TVs use a shadow mask — a metal sheet with tiny holes cut out. The holes ensure that the electron guns hit only the red, green and blue dots of phosphor. Trinitrons use vertical bars of single phosphor color and a picket fence like aperture grille. The aperture grill blocks less of the electron beam than a shadow mask, which results in a much brighter image. Trinitrons also use a single electron gun, with three separate cathodes.

[Alec] is doing some amazing work describing early TV systems and retro consumer electronics over on his YouTube channel, Technology Connections. We’ve added him to our Must watch subscription list.

Interested in retro CRTs? Check out Dan’s article on cleaning up the fogged plastic safety screen on the front of many CRTs.

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Stromberg Carlson Charactron Tube

December 19, 2017 by Al Williams 21 Comments

Flat panel TVs have spoiled us. It used to be that a big display took up a lot of room on your desk or living room because of the depth of the CRT’s electron gun. We wonder what the designers of the charactron would think if they could see our big flat screens today. Never heard of a charactron? Check out [uniservo’s] video of one of these old character display tubes.

You might think the device is just a simple small CRT. However, it is much stranger than that. Inside the tube was a stencil that contained all the characters the device could display. A deflection coil would move an electron beam to light up a particular character. Then another coil would deflect the patterned electron beam to the desired space on the screen. In some cases, the entire set of stencils would get the beam and the first deflection coil would pick which character made it through an aperture. Either way, the tube was not just a display, but a character generator.

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The Nixie Tube Killer That Never Was

October 19, 2017 by Dan Maloney 33 Comments

With the wealth of Nixie projects out there, there are points at which Hackaday is at risk of becoming Nixieaday. Nixie clocks, Nixie calculators, Nixie weather stations, and Nixie power meters have all graced our pages. And with good reason – Nixie tubes have a great retro look, and the skills needed to build a driver are a cut above calculating the right value for a series resistor for an LED display.

But not everyone loved Nixies back in the day, and some manufacturers did their best to unseat the venerable cold cathode tubes. [Fran Blanche] came across one of these contenders, a tiny cathode ray tube called the Nimo, and after a long hiatus in storage, she decided to put the tube to the test. After detailing some of the history of the Nimo and its somewhat puzzling marketing — its manufacturer, IEE, was already making displays to compete with Nixies, and seven-segment LEDs were on the rise at the time — [Fran] goes into the dangerous details of driving the display. With multiple supply voltages required, including a whopping 1,700 V DC for the anode, the Nimo was anything but trivial to integrate into products, which probably goes a long way to explaining why it never really caught on.

If you happen to have one of these little bits of solid unobtanium, [Fran]’s video below will go a long way to bringing back its ghostly green glow. You might say that [Fran] has a thing for oddball technologies of the late 60s — after all, she’s recreating the Apollo DSKY electroluminescent display, and she recently helped a model Sputnik regain its voice.

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Xerox Alto CRTs Needed A Tiny Lightbulb To Function

October 15, 2017 by Al Williams 61 Comments

In the real world, components don’t work like we imagine they do. Wires have resistance, resistors have inductance, and capacitors have resistance. However, some designers like to take advantage of those imperfections, something our old friend [Ken Shirriff] noted when he was restoring the CRT of a Xerox Alto.

[Ken] tried to connect a Xerox monitor to the Alto and — since it was almost as old as the Alto — he wasn’t surprised that it didn’t work. What did surprise him, though, is that when he turned the monitor off, a perfect picture appeared for just a split second as the unit powered off. What could that mean?

Keep in mind this is a CRT device. So a perfect picture means you have vertical and horizontal sweep all at the right frequency. It also means you have high voltage and drive on the electron guns. If you are too young to remember all that, [Ken] covers the details in his post.

He found that the CRT grid voltage wasn’t present during operation. The voltage derived from the high voltage supply but, mysteriously, the high voltage was fine. There was a small lightbulb in the grid voltage circuit. A 28V device about like a flashlight bulb. It measured open and that turned out to be due to a broken lead. Repairing the broken lead to the bulb put the monitor back in operation.

On paper, a light bulb lights up when you put current through it. In real life, it is a bit more complicated. An incandescent filament starts off as almost a dead short and draws a lot of current for a very brief time. As the current flows, the filament gets hot and the resistance goes up. That reduces the current draw. This effect — known as inrush current — is the scourge of designers trying to turn on light bulbs with transistors or other electronic switches.

However, the unknown Xerox power supply designer used that effect as a current limiter. The short 600V pulses would hardly notice the light bulb but if too much current or time elapsed, the resistance of the bulb would rise preventing too much current from flowing for too long. With the bulb open, the negative brightness grid provided an impassible barrier to the electrons. Apparently, the brightness grid lost power a bit earlier than the rest of the circuit and with it out of the way — or perhaps, partially out of the way — the picture was fine until the rest of the circuit also lost power.

We looked at [Ken’s] efforts on this machine earlier this year. Light bulbs, by the way, aren’t the only thing that changes resistance in response to some stimulus. You might enjoy the 1972 commercial from Xerox touting the Alto’s ability to do advanced tasks like e-mail and printing.

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