We love seeing old technology brought back to life, especially when it’s done in the context of how the device was originally intended to be used. And double points when it’s space gear, like what [Curious Marc] and his usual merry band of cohorts did when they managed to light up a couple of real Apollo DSKY displays.
The “Display and Keyboard” formed the human interface to the Apollo Guidance Computer, the purpose-built machine that allowed Apollo missions to fly to the Moon, land safely, and return to Earth. Complete DSKYs are hard to come by, but a lucky collector named [Marcel] was able to score a pair of the electroluminescent panels, one a prototype and one a flight-qualified spare. He turned them over to AGC guru [Carl Claunch], who worked out all the details of getting the display working again — a non-trivial task with a device that needs 250 volts at 800 Hertz.
The first third of the video below mostly concerns the backstory of the DSKY displays and the historical aspects of the artifacts; skip to around the 12:30 mark to get into the technical details, including the surprising use of relays to drive the segments of the display. It makes sense once you realize that mid-60s transistors weren’t up to the task, and it must have made the Apollo spacecraft a wonderfully clicky place. We were also intrigued by the clever way the total relay count was kept to a minimum, by realizing that not every combination of segments was valid for each seven-segment display.
The video has a couple of cameos, like [Ben Krasnow], no slouch himself when it comes to electroluminescent displays and DSKY replicas. We also get a glimpse of well-known component slicer and MOnSter 6502-tamer [TubeTime] too.
13 thoughts on “Apollo DSKY Display Glows Again”
Beautiful! I particularly like how the unlit options are visible, so you can see what the other (inactive) options are. The transition to LCDs on consumer devices hid this often-useful information.
They use a real DSKY power supply.
CuriousMarc says that despite they have the power supply schematic (that doesn’t look very complicated), it is tricky to reproduce because of saturable transformer used for regulation.
But how one could nowadays build a similar high frequency (several hundred kHz) high voltage (230V) AC power supply for similar EL displays like russian ones?
It’ll be easier if you are allow to use modern design tools and technology like switch mode controller chips, transistors or MOSFET. It boils down to an engineering exercise for a specialized supply if you can come up with a requirement specs.
AC supply for EL aren’t supposed to be that high frequency and high voltage. The EL load is essentially a high value capacitor, so it has low impedance at hundreds of kHz and this will draw a very high current. Hundreds of Hz may be.
For “ИЭЛ” type russian displays, i”ve read that required power supply frequency is between 400 and 5000 Hz.
I recognized those large blàck latching relays that were used to operate the lamp, I aquired several from Skycraft Electronics in Orlando a few years ago.
Cool to see a Skycraft shoutout here! I’ll admit, that was the only upside for me when living in Orlando for a year :)
Bingo! That’s where mine comes from!
I’ve been following the AGC restoration for some time and the relay chattering was a surprise
Amazing, imagine all that weight and power consumption on a space flight!
There is a side story about CCA: copper clad aluminum wire. A wire failed and it was CCA. There was a few anecdotes about how the aluminum can corrode and leave just the shell of copper behind. Anyone else have good or bad experiences with CCA? I would imagine there’s a range of quality of CCA depending on how much copper is actually clad onto the aluminum that makes it difficult to compare.
I have used LMR-400 coax for years without issue, it has a CCA center conductor. I do try to limit environmental exposure as it will lead to poor performance.
He didn’t gut the thing and put an Arduino inside it? Is it April 1 already?
I wonder what Fran Blanche thinks about this?
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