This single digit screen is an old edge-lit module that [Ty_Eeberfest] has been working with. The modules were developed for general Radio business as well as have a truly big PCB to manage just one digit. [Ty’s] modules didn’t come keeping that chauffeur board, so he was entrusted to the task of controlling an incandescent bulb for every digit. After a bit of believed he figured it would be much simpler to just replace the edge-light bulbs with a set of LEDs.

We’ve seen these precise modules before, referenced in a job that produced an edge-lit Nixie tube from scratch. Each digit in the screen is made of a piece of acrylic with small drill holes which trace out the numerals. The acrylic is bent to ensure that the edge exits out the back of the module where it picks up light from the bulb. [Ty] laid out his circuit card to ensure that each LED was in the exact same setting as the bulb it was replacing. As you can see, his retrofit works like a charm.

[Thanks Brian]