Re: TI-H: TI 86 backlight project


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Re: TI-H: TI 86 backlight project




The only edge you realy need to be smooth is the edge facing the LEDs 
the other edges can, and probably should be rough. Also, tiny amount of 
reflective material around the other edges may help save light. As for 
thickness, 2mm is about the smallest I've seen and it works nicely. The 
plexiglass can be scored and cracked over the table, as long as the one 
edge facing the LEDs is clear. Part of what makes the Backlight so 
bright is the fact that the LEDs are super brights. they have a narrow 
beam that reaches all the way across. You can go ahead and use lots of 
little surface mount LEDs around it, but you need at least 6 LEDs, 
yellow being one of the best choices. The 6 Superbrights use less power 
than a lot of smaller LEDs. Also, angle the Diffuser a bit. Roll some 
electric tape to form a loop sticky on both sides and use it on either 
the top ot the botom side of the plexiglass. It will raise one end and 
make it a LOT brighter. Also, get the LEDs fairly centered. I built one 
of my best ones yet recently. I tried the angled thing and it works 
nicely.

As for the foam. Get a long, searated knife, a razor saw, or a jig saw 
blade. I like the jig saw blade because it only cuts when you pull it 
away from the LCD. You need to peel all the foam off the LCD and the 
circuit board or it will be VERY tight. You may also need to grind the 
sides of the LEDs themselves down a bit for them to fit. Be sure to 
grind like this:
   ___
  /   \
  |o o| <--Grind this side and the opposite side flat
  \___/

If you wire it correctly (the LEDs are NOT all paralel and they are NOT 
all serial. It's a combination of 2 in paralel, with those groups of 2 
being placed in serial. Follow the instructions CAREFULY. When I get my 
server space I'll try to update every page with photos rather than 
drawings.

Richard Piotter
richfiles1@hotmail.com


>
>
>i dont know about cutting the foam,
>but you need to get 1.5-2.0 mm plexiglass
>1.5 being the best,  dont cut it with a saw beacause that would make 
>rough edges.  you must score it with a razor knife and then break it 
>over the edge of a table or something. or better yet, when you buy it 
>ask them to cut it to the right size,and tell them not to sand the 
edges 
>at all.  you want crystal clear edges for it to work the best(at least 
>this is what i have found)
>and rough top and bottom.  dont use the baseball card holder...i dont 
>see how that would work well.  im sure you can even get the glass store 
>to cut you an old scrap for free. I havent actualy installed one yet 
but 
>i have been playing around with plexiglass and LED's trying to find 
what 
>works best, the thinest plexi that i could get was 2 mill 
>so i dont realy know how good ..say.. 1.0 mm would work, but it might 
be 
>better. I also tryed hot glueing a dozen small super bright surface 
>mount green LEDS around the edge and that seemed to work very well for 
>their size.(not much bigger than a BB).
>I was also thinking of trying find an LED or EL backlit LCD of similar 
>size and use the backlighting components out of that...of coarse it 
>would have to be an old cracked on or very cheap.
>
>
>>From listown@towerguard.unix.edu.sollentuna.se Fri Jan 30 20:55:58 
1998
>>Received: (from majordom@localhost)
>>	by towerguard.unix.edu.sollentuna.se (8.8.8/8.8.7) id EAA31857
>>	for ti-hardware-outgoing; Sat, 31 Jan 1998 04:32:46 +0100
>>Date: Fri, 30 Jan 1998 22:32:41 -0500 (EST)
>>From: Mike <lithium@ntplx.net>
>>To: ti-hardware@lists.ticalc.org
>>Subject: TI-H: TI 86 backlight project
>>Message-ID: <Pine.SUN.3.96.980130222827.2135A-100000@sea.ntplx.net>
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>>
>>I have a question for someone who has successfully installed a 
>backlight
>>into a calc..it seems I can't get my razor to cut the foam on 2 sides 
>of
>>the display, there are ribbon cables that connect the board to the
>>lcd..are there any tricks to doing this without breaking it??
>>
>>AND could someone tell me the thickness of the plexiglass again?  
>>
>>
>>I was thinking of using a plastic baseball-card holder thing...would 
>this
>>work??
>>
>>
>>If i'm missing any other important parts please fill me in..thank 
you..
>>
>>mike orofino
>>lithium@ntplx.net
>>
>>
>
>
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