Okay, so before I continue, I want to ask: is the EL panel always so expensive as $20.00? Is it cheaper anywhere else?

That's quite cheap for an EL panel, in my opinion; where did you get that figure from?

So how many LEDs should I use?

That site from that link...

I'd say that four to six nice bright ones would be sufficient. This topic once again reminds me that I have a great guide to backlighting a TI-89 with EL wire sitting on my hard drive that I have yet to publish here. :/

So, I buy a LED marked with 1000+ mCd and 10mA "forward current"???

Sounds about right to me, if you're going to go with the LED backlighting route. You'll probably need more than one, though.

Well, yeah. I will need more than one. Maybe four. Sorry it took so long to respond, I cannot get on here much.
So, where do I buy these LEDs online? Do you have a favorite site?

No problem if it takes you a while to respond; I certainly understand when life gets in the way. My personal favorite in terms of prices and general selection is LEDShoppe; the only problem for a project like this is that although their prices are excellent, their quantities are far too big for you. Failing that, there's always Sparkfun or Mouse or DigiKey for your LED needs.

Is this the correct one?
3mm size
1010 mcd
20 mA
White color
3.6 v
3.13 dollars

Whoa, 3mm white LEDs? That brightness sounds a bit on the low side and the price a bit on the high side. Again, there's not a single correct one; you want to find low-current, high-brightness, small (3mm is nice, but you might have to go for 5mm and sand them down), for as cheap as possible.

Well, the brightness was supposed to be 1000, and the one I mentioned was 1010. It was supposed to be 10mA, and this one was 20mA. If it's not it, what is? I cannot understand!

On second though I think four to six 1000mcd LEDs should be OK. I believe I was misremembering the brightness of indicator vs. illumination LEDs relative to their mcd rating, so that should be fine. I withdraw my objection.

Good Grief! You're killin' me! Now how do I know what is correct??? Do you know what the stats were on the backlight for the ultimate calculator?

I would kinda like to get this project done, but it is starting to slide to the back burner.

But I really am confused. I am not a techy like everyone else here.

Will this strip of LEDs from a digital camera work for a backlight?


If so, then I wonder how in the world I would go about that...

I'm having difficulty making out what you have there, exactly, but it looks like a strip of four oddish LEDs. I'd certainly think that could work, assuming you could get them all to point into the edge of the LCD properly.

Ok. I will try to do this. What do I do now?

A passel of time later:
I returned to this project with new interest, knowledge, and supplies, and got a serviceable backlight out of 5 LEDs from a caplight. They operate brightly at the full 5 volts of the 4 AAAs, and I used a 10K potentiometer to nicely regulate dimming, and set it in the case perfectly. It really is a work of art now. Seriously, since the TI-83pse has a dysfunctional screen.

So, I bought a dead TI-83+ for $13 on eBay, to salvage it's screen, which was in good shape.

So anyway, my problem now is, I cannot solder the wires from the motherboard the the screen board! Can anyone help me get what I'm doing wrong, please? My supplies are the soldering iron from Walmart, 25W, and the leadless-rosin core solder it came with, and 22-gauge wire from RadioShack. So far, I've been unable to get the wire to actually solder to the pad-thingy on the mobo, except I had success with the first 6 connections (the larger pad-thingys). Thanks!

Can you show us any photographs of your work so far? Leadless solder is healthier, but it sure is a pain to work with in my experience. 22-guage wire is WAY too big; even 24 AWG is too big. It would be good if you can get yourself on some 30 AWG wire. I have documentation on the process here:

http://www.cemetech.net/forum/viewtopic.php?t=5161

Okie-dokie, here is a picture of my work:


And here is a picture of the workplace:

That picture details it all: I spy a soldering iron, a glue gun (overused, naturally), the TI-83+SE, my Helping Hand, small screwdrivers, Sharpie, mascot, multimeter, green 22-gauge wire, old LCD, TI-83+ with new LCD gone, rubbing alcohol, new backlight behind the Helping Hand, clockradio, and the all-important TI-82 screen protector stuck to the wall.

So, Kerm, what kind of solder should I get? I really don't care about whether it's healthier or not.

And where can I get 30-gauge wire? 22 was the smallest they had at RadioShack.