Re-Creating the Apollo DSKY’s Display

Apollo astronauts used the DSKY (Display-Keyboard) to interact with the flight computer with a series of 2-digit codes punched into a numeric keypad. Above the keyboard was a high voltage electroluminescent (EL) display whose segments were driven by electromechanical relays; old-ass technology not seen in operation in decades.

[Fran Blanche] is working to re-create the DSKY’s display, and is raising funds to make her first prototype. She was actually able to go dismantle a real DSKY at the Smithsonian, and this drove her desire to re-create the DSKY’s unusual display.

As [Fran] points out in her video, cinematic re-creations typically involve LED displays and CGI rather than the authentic EL 7-segs. Who would want that when you could have the original?

The DSKY is one of the most recognizable and historically relevant parts of the Apollo Command Module and it’s also quite rare. There are only a handful of  them around and of course none of them work. [Fran]’s display could help museums, collectors — and yes, moviemakers — re-create DSKYs with greater authenticity.

[Fran] is a good friend of Hackaday. If you missed her Hack Chat on antiquated technology last Friday you can check out the transcript here.

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Hackaday Links: Leap Eve, 2016

The current Mac Pro is a masterpiece of design that looks like a trash can. We’ve been waiting for someone to take one of these computers and stuff a MiniITX board in there, but seeing as how the Mac Pro costs $3000, that probably won’t happen anytime soon. Here’s the solution. It’s a trash can computer case that is also too expensive for what it is. Now all we need is someone to put a big fan inside one and turn this computer into a wacky waving inflatable arm flailing tube man.

[Mike Harrison] recently got his hands on a $20,000 SPARC CPU module. This is an enormously thick board that must be dozens of layers thick. How many layers was an open question until he put the board in a CNC milling machine. The setup is pretty much what you would expect with a few lines of g-code repeated over and over. The real trick comes from using one of the outputs for lubricant to trigger the shutter release on a camera. How many layers were in the CPU module? About 30, or something like that.

Almost a year ago, we saw the latest advances in perfboard. It was a perfboard with each hole connected to rows and columns on a selectively solderable orthogonal busses. Something like that. Actually, we still can’t wrap our head around it. Now, it’s a crowdfunding campaign with a few new and useful features. There’s also a layout tool that will show you where to place your components and where to make solder bridges.

[Ray Wilson] started Music From Outer Spacethe place to learn about DIY analog synthesizers. Ray now has cancer, and as you can imagine, being a self-employed engineer specializing in analog synthesizers doesn’t provide great health coverage. [Ray]’s family set up a GoFundMe page to pay for the medical expenses.

We haven’t seen much in the land of 3D scanners, and we’re betting most of that is because they’re so expensive. The guys from CowTech have a kickstarter up for a 3D scanner that’s just $99. It’s based on the Ciclop scanner but designed around a custom Arduino shield and remains fully open source.

Remember the screen printed electroluminescent displays that were printed directly onto t-shirts from a few months ago? Now that company is working on a much cooler design: the Hackaday Jolly Wrencher. It works, but there are still a few problems: they’re setting the shirt on fire a little. Don’t worry, if these are ever reasonably safe and somewhat affordable, an EL Jolly Wrencher shirt will be in the Hackaday Store.

Need a rechargeable multimeter? It’s actually pretty easy. With an 18650 Lithium Ion cell and a 9V boost converter, this circuit will fit in most devices that need a 9V battery. To do this right, you’ll also need a USB charging port, to be used once every couple of years when the battery needs charging.

Screen Printing Electroluminescent T-Shirts From Tron

Travel around to enough security conferences, faires, and festivals, and you’ll see some crazy wearable electronics. Most of them blink, and most of them use LEDs. Electroluminescent panels are used for wearables, but that’s a niche – the panels are a little expensive, and you have to deal with high frequency AC instead of the much simpler, ‘plug in a LiPo here’ circuit LED-based wearables have to contend with.

Still, electroluminescent panels are cool, and thanks to how EL panels are made, you can screen print EL displays. That’s what some of the guys at AMBRO Manufacturing did recently: screen printing electroluminescent lights directly onto garments. It’s t-shirts from Tron made real.

EL panels and EL wire are really only three separate parts: a conductor of some sort, a phosphor, and another conductor. Pass a high-frequency AC current through the conductors, and the phosphor lights up. With EL wire, it’s a thick copper wire clad in phosphor and wrapped in a very fine copper wire. EL displays are made with conductive ITO-coated glass or plastic. It’s a relatively simple construction, and one that is perfectly suited for screen printing. In fact, one of the first EL displays – the DSKY, the user interface for the Apollo Guidance Computer – used screen printed seven-segment EL displays.

The folks at AMBRO only have a proof of concept right now, but it is a completely screen printed electroluminescent design on fabric. To light it up, the t-shirt will need an inverter, but this is the beginnings of t-shirts from Tron.

Video below.

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Reproducing A DSKY

This is a project that is about a year and a half in the making, but [Fran] is finally digging into the most iconic part of the Apollo Guidance Computer and building the most accurate reproduction DSKY ever.

The Apollo Guidance Computer was a masterpiece of engineering and is frequently cited as the beginning of the computer revolution, but it didn’t really look that interesting – it looks like a vastly overbuilt server blade, really. When everyone thinks about the Apollo Guidance Computer, they think about the DSKY, the glowey keypad interface seen in the blockbuster hit Apollo 13 and the oddly accurate disappointment of Apollo 18. It’s the part of the Apollo Guidance Computer the Apollo astronauts actually interacted with, and has become the icon of the strange, early digital computers developed for NASA in the 60s.

There are a few modern DSKY replicas, but all of them are exceedingly anachronistic; all of these reproductions use seven-segment LEDs, something that didn’t exist in the 1960s. A true reproduction DSKY would use custom electroluminescent displays. These EL segments are powered by AC, and transistors back then were terrible, leading to another design choice – those EL segments were turned on and off by relays. It’s all completely crazy, and aerospace equipment to boot.

Because of the custom design and engineering choices that seem insane to the modern eye, there isn’t much in the way of documentation when it comes to making a reproduction DSKY. This is where [Fran] tapped a few of the contacts her historical deconstruction cred earned when she reverse engineered a Saturn V Launch Vehicle Digital Computer to call upon anyone who would have access to a real Apollo-era DSKY.

The first contact was the Kansas Cosmosphere who was kind enough to send extremely detailed photographs of the DSKYs in their archives. It would have been extremely nice to have old documentation made when the DSKYs were rolling off the assembly line, but that information is locked away in a file cabinet owned by Raytheon.

[Fran] got a break when she was contacted by curators at the National Air and Space Museum’s Garber facility who invited her down to DC. She was given the grand tour, including the most elusive aircraft in the museum’s collection, the Ho 229, the dual-turbojet Nazi flying wing. At the Garber facility, [Fran] received permission to take apart two DSKYs.

The main focus of [Fran]’s expedition to the Air and Space Museum was to figure out how the EL displays were constructed. The EL displays that exist today are completely transparent when turned off because of the development of transparent conductors.

The EL displays in the DSKY were based on earlier night lights manufactured by Sylvania. After looking at a few interesting items that included Gemini hardware and early DSKYs, this sort of construction was confirmed.

With a lot of pictures, a lot of measurements, a lot of CAD work, and some extremely tedious work, [Fran] was able to create the definitive reference for DSKY display elements. There are 154 separate switchable element in the display, all controlled by relays. These elements are not multiplexed; every element can be turned on and off individually.

Figuring out how the elements were put together was only one part of [Fran]’s research. Another goal was to figure out the electrical connections between the display and the rest of the DSKY. There, [Fran] found 160 gold pins in a custom socket. It’s bizarre, and more like a PGA socket than like the backplane connector [Fran] found in the Saturn V computer.

Even though [Fran]’s research was mostly on the EL panel inside the display, she did get a few more insights with her time with the DSKYs. The buttons are fantastic, and the best keys she’d ever used. This is just part one of what will be an incredibly involved project, and we’re looking forward to what [Fran] looks into next.

Building EL Displays On A PCB

ELElecrolumiscent displays have seen a huge swing in popularity recently, but only in limited forms like EL wire or flat EL panels. You can, of course, cut and bend these wires and panels to suit any purpose, but custom shaped EL displays are just the bee’s knees. They’re not hard to fabricate, either: with cheap custom PCBs, all it takes to make custom EL panels is just a few chemicals.

[Nick]’s method of fabricating custom EL displays uses an exposed copper layer on a PCB you’d pick up from OSHpark or any of the random board houses in China. The process consists of designing a display – be it a few letters, pixels, or a seven-segment arrangement. The display ‘stack’ is a layer of painted-on dialectric, a phospor, and finally a translucent conductive ink that connects the display segments to ground. It looks like an extremely easy process, and from the pictures it looks like [Nick] is making some EL displays of reasonable quality.

[Nick]’s work was inspired by the grand poobah of homebrew electrolumiscent displays, [Jeri Ellsworth], who managed to make a similar EL pixel on a PCB. [Nick]’s display looks great, though, and with a little work some custom segment displays should be very possible.

High Voltage Hacks: All About Electroluminescence

Although many might not know it, electroluminescent materials use high voltage, and thus qualify for our featured topic. Many may assume that these sheets work in the same way as LED lights, using low-voltage DC power.  This, however, is not the case, as they need around 100 volts of AC current to allow them to light up.

For a battery-powered solution, this means converting the battery’s DC power to AC. Adafruit has a good tutorial about working with EL wire and powering it up using a portable inverter. One should obviously be careful to properly insulate any clothing using this material as being shocked is generally not fun.

The video after the break is pretty long, but is well produced and will give you a good background of EL use. If you don’t have 30 minutes to dedicate to this, be sure to at least skip to 2:43 to see one of the coolest EL shirts we’ve seen. Continue reading “High Voltage Hacks: All About Electroluminescence”

Jeri makes flexible EL displays

A failed chemistry experiment led [Jeri Ellsworth] to discover a flexible substrate for electroluminescent displays. We’re familiar with EL displays on the back of a glass panel like you would find in an audio receiver, but after making a mesh from aluminum foil [Jeri] looked at using the porous metal to host phosphors. She starts by cleaning foil and using a vinyl sticker to resist etching portions of the aluminum. It then goes into a bath of boric acid, electrified with the foil as the anode. As the foil etches she tests the progress by shining a laser through the foil. After this the phosphors are applied to the back surface of the foil, covered in a dielectric, and topped off with a conductive ink that will carry the AC necessary to excite the phosphors. This is layering materials in reverse compared to her EL PCB experiments. See [Jeri] explain this herself in the clip after the break.

You can see above that this produces a pretty well-defined display area. It reminds us of that color changing paint display. We think it would be worth a try to build a few 7-segment displays using this method.

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