TI-H: Re: Backlighting

To: windowswiz@ibm.net, ti-hardware@lists.ticalc.org
Subject: TI-H: Re: Backlighting
From: "Richard Piotter" <richfiles@hotmail.com>
Date: Tue, 23 Sep 1997 11:04:26 PDT
Reply-To: ti-hardware@lists.ticalc.org

>How is your system accomplished?  I'm working on something similar, but
>I can't get it to work...
>
>Thanks.
>-- 
>- Brandon Turok

I am currently using 6 LEDs, green works best from my tests. I want to 
order some green superbrites. They produce 500 mcd. There is a yellow 
one that does 550 mcds, but it uses 4ma more, and that extra current may 
eat the batteries faster. Yellows seem to work nice, but I only have dim 
yellows now so the brightness test was a bit biased towards the green. 
The reds are difficult to read and they cause pixel shadows. The green 
doesn't cause the shadows, and is very easy to read. I want to order the 
yellows anyway, because I can use them in my models if they don't look 
good. I think the key would be the superbrite LEDs. RadioShack only 
sells red superbrites. The reds are hard to read. I'm going to order the 
green and yellow superbrites soon and test it. 

The dim greens light about an inch square area when held over. I'm going 
to use reflective tape in the sides of the case to help reflect the 
light onto the screen more. I may need to set the screen further to the 
rear of the calculator to make room for the LEDs and I'll probably grind 
the LEDs thinner. The TI-85 screen is a bit thicker than an 82 screen 
because it uses three surface mount chips rater than the COB (chip on 
board) style chip the 82 uses. Those thicker chips reduce the space the 
screen can move back. That is the #1 difficulty. I want to see if I can 
modify the case for it to fit better inside the calc.

I'll keep updates on the list and let everyone know if it works well.

Richard Piotter

e-mail: richfiles@hotmail.com

home page: <A 
HREF="http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html">The 
Richfiles</A>

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