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This device is considered to be the first of it's kind, a 7-segment display made from LEDs. While this type of display had been around before, previous incarnations used neon lit segments (NIXIE) or Incandescent (Numitron) filaments to display numbers. This allowed digital displays to be driven directly from logic circuitry, without the need for voltage translators or other drive circuitry.

These are original production MAN-1, and are evidenced by the M printed on top, and the clear case, the latter being replaced by a red lens in later production to hide the internal circuitry. Monsanto did license out the technology to other manufacturers, but these are made by the parent corporation and were originally sold to the Bell System for use in telephone switching products.

Here's a page showing the devices lit. They're not really that bright.

This device is considered to be the first of it's kind, a 7-segment display made from LEDs. While this type of display had been around before, previous incarnations used neon lit segments (NIXIE) or Incandescent (Numitron) filaments to display numbers. This allowed digital displays to be driven directly from logic circuitry, without the need for voltage translators or other drive circuitry. These are original production MAN-1, and are evidenced by the M printed on top, and the clear case, the latter being replaced by a red lens in later production to hide the internal circuitry. Monsanto did license out the technology to other manufacturers, but these are made by the parent corporation and were originally sold to the Bell System for use in telephone switching products. Here's a page showing the devices lit. They're not really that bright.

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[–] • 1 pt

Those are cool displays. I think I may have a couple of them laying around, but not enough to do much with.

[–] • 1 pt

Look for old 'Pro-Bel video router matrix' on eBay, they use something like this. The resale of parts would probably cover the cost

[–] • 1 pt

Very nice. Old commercial video equipment, it looks like.

In a former life, I used to work with these things that had the same displays. Since they were made right up until the mid-late 2000s, I would suspect that Aeroflex had the remaining new stock on TIL311 displays.

https://userequip.com/product/IFR-Aeroflex-Comstron-FS2000D-18-18.4GHz-Frequency-Synthesizer-FS2000B-FS2000A.html