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bobyong808
Newbie
Joined: 24 Sep 2010
Posts: 3
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 Posted: 26 Sep 2010 04:47:28 am Post subject: |
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I've read through the backlighting mods for ti-83,84 and 86.
The one thing that makes me reluctant to perform this mod is where the switch would go.
[font="Arial Black"][size="7"]HOWEVER[/size]
I've found this incredible EL inverter that would be small enough to fit within the calculators itself. http://www.supertex.com/pdf/misc/HV833DB1.pdf The circuits have a Vdd input that allows you to turn off and on the el inverter by voltage control.
Now the only problem i have is which part of the calculator can i tap a voltage such that the el panel only turns on when the calculator is on.
Does anyone know where this voltage drop is available on the circuit board? Would the Voltagein for the ICs work?
THANK YOU IN ADVANCE |
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AHBAD_ALVIN
Advanced Newbie
Joined: 18 Sep 2010
Posts: 74
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| Posted: 26 Sep 2010 08:12:55 am Post subject: |
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cool, I was actually looking into a backlight right now too, so I could use my calc whenever...
sorry though, can't answer your questions, but I do wish you good luck  |
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zenome
Newbie
Joined: 01 Oct 2010
Posts: 7
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| Posted: 01 Oct 2010 03:03:26 am Post subject: |
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ASHBAD_ALVIN wrote:
cool, I was actually looking into a backlight right now too, so I could use my calc whenever...
sorry though, can't answer your questions, but I do wish you good luck
I would advise against installing a backlight if you've never done one before. (I've broken one calculator). Anyhow the EL method is not a very good choice because the hours that the EL light runs is limited. Usually, around 10,000-20,000 hours of life. I make my own backlight device. I use plexiglass and dremeled LED lights. It used to took me a few days to install a backlight. Now I can install one and have it fully working condition with a micro-switch (tiny) pencil tip switch controller installed in about 45 minutes. Check out one of the calculators I did in the past. I sold this one on ebay for $99.00. It is one of the cleanest installs for a backlight.
http://www.youtube.com/watch?v=JmxTIeyWelg
On a side note, I am making a prototype backlight that uses 1 LED with the incorporation of fiberoptic fabrics. Google fiberoptic backlight for details. This is probably the best method for battery life and a nice equal distribution of lighting, plus 100,000 hours of life expectancy from the LED bulb.
I've backlighted an TI-84+, multiple TI-83+ and SE. Now for my next project I will do a TI-89t, which is very similar to the TI-84.
The best place to add microswitches depends on the type of switch you buy and the form factor. The best one I've used is a micro slide switch. These are cheap and easy to install. Check this image to see how it looks when I've installed them. Its one of the cleanest looks ever, and I have seen some ugly switch installs.
http://www.imagebam.com/image/544134100134499
I was planning to add more backlights to the buttons but got lazy, its really easy thing to do also.
Last edited by Guest on 01 Oct 2010 03:40:44 am; edited 1 time in total |
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bobyong808
Newbie
Joined: 24 Sep 2010
Posts: 3
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| Posted: 01 Oct 2010 11:04:39 am Post subject: |
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| How do you actually "break" a calculator? I was wondering what to look out for. I really want to see how its like behind the screen. |
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zenome
Newbie
Joined: 01 Oct 2010
Posts: 7
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| Posted: 01 Oct 2010 12:09:04 pm Post subject: |
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bobyong808 wrote:
How do you actually "break" a calculator? I was wondering what to look out for. I really want to see how its like behind the screen.
Well that totally depends on your form factor. If you were to open a TI-84 (new form factor) then do not use a flat screw driver to try and pry open the case. In either case, pry the case on the sides, and don't ever do it on top (although easiest if u know how).
You can break the calculator several ways. One way is when you remove the aluminum rectangular support that is glued behind the screen. If you mistakenly cut through the ribbon cable its a goner. If its your first time, you will need a lot of patience. Sometimes, when you try to pry it fast you either A) cut your fingers with a razor blade and end up with a bloody mess or B)cut and destroy the calculator.
And always tape down the ribbon cable, if you're going to remove the screen as this prevents accidental cable tear if you were to leave it hanging. I will list the steps on how to remove the screen for backlighting, although if you're a noob, like I said before, be prepared to break one or two calculators before success. On my first attempt awhile back, I destroyed a TI-83+ silver edition and was very dreadful and never tried again, tell a year or two. Now I'm an expert and can install a very clean backlight calculator in about an hour.
Materials needed:
tools to open the case.
razor blades, naphtha or alcohol solution, dremel, plexiglass, wires, solder, microswitch, various types of tapes, and patience
PREPARING THE LCD SCREEN
1.) remove case
2.) remove board from case
3.) (important) start removing the aluminum rectangular bracket from the electrical board first, (not the LCD).
4) once it is removed, you should be able to fold the LCD up and down, giving a better work angle. Now start removing the aluminum bracket from the LCD. Be very careful not to get into the polarizer film.
5.) After removing the aluminum bracket, attempt to separate the polarizer from the reflector film.
6.) The reflector film and polarizer film is extremely close, so use a razor blade to separate them and watch the front of the LCD screen if you penetrated the polarizer or reflector. (note: on newly manufactured TI-83+ and TI-84+ or TI-89 will all have the reflector and polarizer in one single film, thus it is extremely hard to separate them, so you will have to buy a polarizer film, the best one is the transmissive type (for backlighting applications). Buy only the non-adhesive polarizer film, DO NOT BUY adhesive polarizer films, you will regret it, as you will find out why below.
7.) So if you have to discard the polarizer film because the TI-83+ is too new, then you will just need to place a polarizer film in the back. (little cleaning is needed, this probably saved you the most time)
8.) If you manage to remove the reflector film without destroying the polarizer film, here is the hard part. Start cleaning the sticky layer of adhesive glue from the TI-83 calculator. The best method I've found is to use a very sticky tape like duct tape. Then start folding the duct tape like a cigarette (sticky side out). One by one you must place it on the back of the screen where the polarizer is at and attempt to lift the sticky adhesive off the film. This could take anywhere from a couple of hours to 4-6 hours! Thats why if you got some polarizer films, you can pretty much skip this step and trust me it is the longest step.
PREPARING THE LCD BACKLIGHT (special type with even distribution) SKIP this step if you are using EL backlight, you're ready to install if that is the case.
1.) Use a very thin plexiglass and take that piece of aluminum that was taken out earlier as a guide for the size and dimensions of the LCD backlight section.
2.) Cut the plexiglass near the size of the rectangular aluminum piece, try to make it at least 1-3mm shorter on all size. It has to be slightly smaller, this will save you time later on if you have fitment issues otherwise it will be an extremely tight fit.
3.) Sand corners as well as both sides of the faces, this will diffuse the LED light so that it is evenly distributed.
4.) Dremelize the 4 LED lights to a square shape. It should be around 1mm by 1.25mm if you've done it correctly, remember the backlight is extremely thin, and you could risk breaking your LCD if you don't make it as thin as possible (when you put it back together).
5.) Cut 4 sections of the corners of the rectangular plexiglass pointing diagonally of course, cut it the size of those LEDs 1.25x1mm (of course a little bigger so they can fit).
6.) After that, super glue them and solder them so that you have 2 wires hang out (in parallel) only 2 wires should hang out.
7.) Test the LED panel to see if it works, it should be very bright once you completed. The lights positioned diagonally has the best light distribution, I've experimented, with 4-6-8 lights. The diagonally one looks the best.
8.) Use a very clean piece of printing paper. Cut it to the size of the plexiglass and super glue or tape that on.
9.) Install microswitch (separate step, requires specialize glue and adhesives)
10.) Wire and solder, and snug the cables properly in the proper place.
11.) Reinstall and test to see if your light works.
In a nut shell that is how you install a backlight, although there are other minute steps and tricks not mentioned because I'm too lazy to post pictures and instructions.
All this is doable in about 45 minutes to an hour. Of course if its your first time, it can take as long as 8 or more hours.
I don't usually do this but I can install one for you if you like, for $50 plus shipping. Thus you won't risk the damaging a calculator plus if you were to buy all the tools and materials needed, it would cost more than $50.
Last edited by Guest on 01 Oct 2010 12:29:31 pm; edited 1 time in total |
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Madskillz
Active Member
Joined: 02 Jan 2004
Posts: 608
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| Posted: 01 Oct 2010 07:53:01 pm Post subject: |
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| That is an awesome job on the backlighting. I planned to do that to my old 83+ eventually. Thanks for the guide. |
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zenome
Newbie
Joined: 01 Oct 2010
Posts: 7
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| Posted: 02 Oct 2010 11:59:41 pm Post subject: |
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The most trickiest part about installing the LED backlight is removing the aluminum bracket from the LCD panel. The best method and probably the fastest (about 10-15 minutes), is to remove the bracket from the circuit board before you separate the aluminum bracket from the LCD. That is probably the most important step in the whole process and many how-tos fail to mention that fact. If you remove it from the LCD screen first, you risk tearing through the polarizer film or even cutting the ribbon cable (my first time mistake). Removing it from the circuit allows you to practice and get a feel of how to remove the adhesive from the board. The best method is to work around the sides (the 3 corners of the rectangle). Then use a slightly long rectangular blade to dive straight on the long side of the screen (its usually the bottom). Gently guide it in there and apply some alcohol or naphtha, attempt to move the blade back and forth as if you were slicing meat. If you removed the adhesive correctly (use naphtha or alcohol solution for every penetration with the razor blade), it should slide down really easy. Then once you a little over half way through, all you have to do is turn that blade like a screw driver, and it slides off easily. You will hear a gluey sticky sound, kind of like peeling tape. If you've mastered this step, all the other steps are easy and fun and there is no more high risk factors involved.
And one more thing, using LED is way better than using EL panels. There are a few disadvantages for using an EL panel.
Disadvantages of EL panels:
1) Space requirement is high, (inverter is required)
2) Low life expectancy (3,000-10,000 hours) vs 100,000 LEDs
3) Lighting is not that bright
4) El panels are way more expensive than LED. $20-40 avg. vs LED $4-8 (materials included)
Disadvantages of LED:
1) Light distribution is not evenly distributed, (this can be corrected if you use fiber optic fabric)
2) Requires precise soldering for custom panels (has to be very thin)
Overall if you've modified your TI-83+ using 3mm LED, you will have a much longer lasting backlight vs EL panels. Not to mention brighter as well.
Last edited by Guest on 03 Oct 2010 12:12:34 am; edited 1 time in total |
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bobyong808
Newbie
Joined: 24 Sep 2010
Posts: 3
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| Posted: 03 Oct 2010 09:34:27 am Post subject: |
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THANKS FOR THE IN DEPTH GUIDE!
Are the Ti-83 and 84 quite similar in terms of taking them apart?
Also, have you considered using transistors to tap on the calculator circuit itself, such that when it turns on there will be a small current into the transistor base, and the transistor will switch the LEDs on? This way you don't even need a switch and it turns on and off whenever the calculator itself does. |
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AHBAD_ALVIN
Advanced Newbie
Joined: 18 Sep 2010
Posts: 74
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| Posted: 03 Oct 2010 03:33:41 pm Post subject: |
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Yeah, the tutorial is pretty good. Thanks, man!
But no, the 83+ and 84+ are a bit different in layout in some ways I've heard -- but I haven't actually opened one up. |
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zenome
Newbie
Joined: 01 Oct 2010
Posts: 7
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| Posted: 04 Oct 2010 06:07:25 pm Post subject: |
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bobyong808 wrote:
THANKS FOR THE IN DEPTH GUIDE!
Are the Ti-83 and 84 quite similar in terms of taking them apart?
Also, have you considered using transistors to tap on the calculator circuit itself, such that when it turns on there will be a small current into the transistor base, and the transistor will switch the LEDs on? This way you don't even need a switch and it turns on and off whenever the calculator itself does.
Yes I have considered the transistor and photoelectric switches but it is far more work than the regular switch. Plus, a manual switch gives you more flexibility.
This is a good one I made(sold), but I also got another silver edition one that is blue instead of white. I will post pictures of my TI-84+ SE and TI-83+ SE this weekend with backlights. (I'm going to make about 3-4 of them this weekend.)
 
 
It doesn't seem that bright when there is a brighter light source to it (camera flash), but it is very bright in the dark or mildly lighted areas. The blue one that I recently did was less bright than these but never the less, it is way brighter than the EL panels.
This one was an extremely customized one, it has not 1 but 2 micro controller switches that can be flicked on by a pencil or pen or by your thumb (squeeze and pull). Whenever you graph this calculator, you can speed up the clock rate with the other manual switch, it graphs at 27.8MHz, 12MHz more than stock, thus it is very fast. I down clock it when not in use (turn switch down) this saves energy substantially. It should be noted that these switches does not affect the case cover, since it is extremely small, about double the size of the screws when you open them (width).
Here is a picture of the switches that I use, you can virtually add them anywhere on the calculator. There are limitless possibilities with these switches. All you need to do to install them is dremel a straight line (about 4-5mm) and then install with tiny amounts of super glue (hold it in place) then use a hot glue gun to make it permanently placed.
Oh and the TI-83 and TI-84 is similar to taking apart, but when you take them out, be very careful on the TI-84s. Many idiots (me) have place a tiny screw driver to pry it and without realizing that the newer models have the ribbon film integrated on the top side.(The difference is a slightly more curved designed case, and one full board instead of 2 like the old cases, other than that, they are pretty much the same.) Thus, if you pry it, when you insert the screw driver, you virtually sliced through the ribbon cable and you will having missing pixels when you put them back together. I didn't even pay attention when I got it open, after removing the metal bracket and realizing that fact (LCD was finish in prep process), I was pissed off.
Last edited by Guest on 04 Oct 2010 11:56:22 pm; edited 1 time in total |
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zenome
Newbie
Joined: 01 Oct 2010
Posts: 7
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| Posted: 06 Oct 2010 04:42:27 pm Post subject: |
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I've found an alternative method or application that could possibly extend the life expectancy of a backlight without using much power and resemble EL panels (with uniform lighting). I will post information about this later when I re-modify a couple of backlight projects.
I should call this the Hybrid Backlight Approach. I will post it in another forum and possibly make an in-depth guide.
Last edited by Guest on 06 Oct 2010 04:51:27 pm; edited 1 time in total |
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Madskillz
Active Member
Joined: 02 Jan 2004
Posts: 608
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| Posted: 06 Oct 2010 09:36:27 pm Post subject: |
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| Keep us posted I got an old 83+ sitting around that I wouldn't mind backlighting. |
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zenome
Newbie
Joined: 01 Oct 2010
Posts: 7
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| Posted: 17 Oct 2010 05:54:14 am Post subject: |
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Well I didn't get a chance to test my new hybrid backlight, I did however installed a backlight on a regular TI-83 plus. Check this one out. 
Last edited by Guest on 17 Oct 2010 05:57:11 am; edited 1 time in total |
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Calculator Modifications => Calculator Hardware, Electronics, Robotics
