PiDP LED size

[Reynald Poittevin]

Just a design tip...

Since the "real" PDP-11/70 has 5mm LEDs and PiDP is a 6/10 scale replica, we should use 3mm LEDs instead of 5mm ones.

Actual PCB is not a problem since 5mm and 3mm LEDs have the same pin spacing (200 mil), but the LED cover must be drilled with 3mm holes instead of 5mm ones.

And I don't know if Oscar could find the same 700nm "deep cherry" LEDs in 3mm size?

[Oscar Vermeulen]

Reynald,

On Tue, 12 Jan 2021 at 09:34, Reynald Poittevin <rey...@poittevin.name> wrote:

Since the "real" PDP-11/70 has 5mm LEDs and PiDP is a 6/10 scale replica, we should use 3mm LEDs instead of 5mm ones.

Mathematically, that would be logical. But using 3mm LEDs looks really ugly in practice, I built one with 3mm LEDs and recoiled in horror  :)

So I kept the LEDs at 5mm.

And I don't know if Oscar could find the same 700nm "deep cherry" LEDs in 3mm size?

I built the first prototype with 700nm LEDs, you can still get them. They are quite expensive by now, however, and need loads more current.

The acrylic front panel actually has a coloured 'sunglass effect' that brings the colour of modern red LEDs closer to the old 1970s ones - which I thought was a neat trick :)

Kind regards,

Oscar.

[Rob Pike]

Although I admit the scale would suggest 3mm LEDs, part of what makes the PiDP-11/70 so nostalgic for me is that the LEDs on it look _exactly_ right, even though the rest of the item is scaled down.

-rob

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