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Comment by tal8d | Hacker News Reader

Yeah, the HDSP-2132 is a common display component in military hardware. I'm sure that readability figures into it (especially for NVGs), but so does hardiness. My hopes of an 80x24 dumb terminal were dashed when I finally learned the unit replacement price... I don't need a rad hardened serial display that bad.

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I've been looking into those Avago/Broadcom dot matrix displays recently. I don't think it'd be too hard to recreate something similar with tiny SMD LEDs on a PCB and a slightly intelligent driver board, for much cheaper. Would there be a market for something like that?

Only if you can get them listed at Digi-Key/Mouser/etc. Even if it's under a "maker" brand like Adafruit, Sparkfun, etc. Anyone who can replacement TIL311 and friends displays in there, and advertise them, will sell quite a few.

They're not hard to make, but they're the sort of thing that no one really wants to make in-house, since they're a means to an end rather than an end in themselves. Great thing to sell, though!

It has been done a few times, but I doubt there would be any kind of market for it. https://hackaday.io/project/85515-redotmatrix

Electroluminescent glass panels on the other hand... https://www.youtube.com/watch?v=Z2o_Sp2-aBo

That redot project seems like perfect candidate for a kickstarter

In grad school I taught a electronics lab class where the students would burn through a bunch of HDSP-0772 every semester. I thought about coming up with a replacement, but at the time you could still get them for a somewhat reasonable price (like $10 or $20?).

At today's price of $50 it might be cost effective to do as you say, but I imagine there's not a huge market.

That would be roughly a 0.75mm pitch.

Not rad hardened, and not quite 0.75mm, but you can buy a 1.25mm pitch LED matrix panel for a relatively low cost. It's an RGB panel instead of monochrome for the HDSP-2132.

https://www.alibaba.com/pla/Hot-sale-small-pitch-led-display...

Is over $100 that low cost? Surely there could be better prices.

19,200 RGB LEDs plus all the mux chips adds up, but these signage modules are significantly cheaper than anything else with discrete separate LEDs.

Unless I'm misreading the page, it is claiming a resolution of 104x78. So that means 8,112 LEDs.

The HDSP-2132 is made of 8 character elements, each element has a resolution of 5x7. So a 80x24 terminal would have a resolution of 400x168... 67,200 LEDs.

So about a magnitude off, even before ignoring the built in character spacing :)

I wasn't suggesting one of them would settle the matter. I was suggesting it would be cheaper to use them instead. They are made to be grouped together, and daisy chained to a single controller.

I believe each module would be 160 x 120 dots (19,200 dots total) though, based on module size and LED pitch. I'm unclear on where you got 104x78.

> I'm unclear on where you got 104x78.

https://www.alibaba.com/product-detail/Hot-sale-small-pitch-...

    Module  Res     Size
    P1.923  104*78  200*150

I went ahead and counted... 128x96 (12,288 LEDs)

https://imgur.com/a/4qdY1Pr

It's just bad pictures and errant info.

Here's a better link: https://www.aliexpress.com/item/32965783207.html

It's 160x120, as I mentioned for a 200x150mm P1.25 led module. You just divide the width/height by the pitch to see the number of dots.

As far as I can tell, 1.25mm is the smallest pitch available for these modules.

lol, I marked every tenth led manually and counted twice - the number is correct, the marketplace is wrong.

https://imgur.com/a/NqVXtDd

https://www.mblock.com.tw/upload/Investor/events/2020/202008...

You counted dots on a picture of something other than a "200mmx150mm P1.25 led module". Pitch is the distance between the center of each LED.

1.25mm x 160 = 200mm

1.25mm x 120 = 150mm

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