Ken ShirriffJul 21, 2025
We obtained a mysterious box of 1960s electronics. I reverse-engineered it and with much effort, we got it running. It turns out to be a test unit for testing NASA's Up-Data Link, a system from the Apollo moon landing to control the spacecraft from the ground. Let's take a look inside... 1/n
Show threadKen ShirriffJul 21, 2025
This box has thirteen orange digits at the top, which look like Nixie tubes. But they are a different technology called edge-lit lightguide display. Each digit has ten plastic sheets and ten lightbulbs. Each sheet has dots etched in the shape of a number. Lighting a sheet lights up that number.
Show threadtrusty falxter 🧠
@kenshirriff Oh, nice! I didn't even know that this technique was used in the past. I always thought it was a modern/cheap way to imitate the look of Nixie tubes.
Jul 21, 2025 at 4:44pmWeb
Show threadChris MurphyJul 21, 2025
@flxtr @kenshirriff I don't know the vintage of the controls, but when I took a nuclear engineering class back in the '80s at WPI, the reactor control panel used this type of stacked display to indicate the control rod depth. Was amusing to see digits go deeper into the panel as the numbers changed.