Making large numeric displays - test-drb@ccmp.vtda.org

4 Oct 2006

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Subject: Re: Making large numeric displays
   From: "Ethan Dicks" <ethan.dicks at gmail.com>
   Date: Thu, 05 Oct 2006 12:43:36 +1300
     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>

On 10/5/06, Jules Richardson <julesrichardsonuk at yahoo.co.uk> wrote:
  I hit on the idea of a big wall-mount Sudoku
game, either controlled purely by
 TTL logic, or by some 'period' single-board machine....

 Yep - given the application, I expect each digit probably needs to be 3-4"
 tall to give a game grid height of somewhere around 3ft. 
I like the idea of the 9-layer plexiglass sandwich displays (you don't
need '0' for your application), but I _have_ seen 3"-4"-tall 7-segment
displays.  We have a "mission control" type clock here (not GPS
controlled, but does have an NTP client onboard).  I haven't measured
the LEDs personally, but the clock is over 3' long.

A quick google search on '4" 7-segment display' gives this as the second
hit...

http://www.elexp.com/opt_0165.htm

$8 each (q. 10) doesn't sound bad, but 81 of them is a fair quantity.
Perhaps you could negotiate a slighty lower q. 100 price?

This sounds like a fun project.  Good luck with it.

-ethan 
A bunch of years ago I needed some larger LED displays, 2.5 inches 
(~76mm) and the solution was very cheap.  I used stycast a black resin 
potting compound and lexan.  A block of wood to hold the lexan peices,
a rubber mold made with silastic (RTV) was most of it. Three red leds 
to a segment and a little work finishing the face flat and ta daa, 
big segments that only needed ~6V at 25ma each.  Very cheap to make.

Edge lit lexan is very good looking and decent brightness. With the 
new high output leds both color and greater brightness would be easy.
The trick is the lit end is clear by polish or solvent and the display 
side is matt finish (polish to 400 grit).

Allison