It would be much easier with two keyboards instead of one as in the case of the TI. Much worst with a single tactile screen in Apps. I better follow your construction advice. In the meantime I learn basic stuff about electronics.
The idea of two keyboards is because I dont want to select in any form the display I want to enter the numbers. Instead, one keyboard for each display and a third display that shows the result. Is like you said, I´d like it to be able to always do the calculations as the numbers are entered.
The main requirements are.
The displays, keyboards and calculation things.
One button for each display that clean them separately. It would be great if after 1sec i.e. of entered the number in each display, you dont have to clean them but just enter the next ones for the next calculation. The idea in arbitrage betting is reduce time between the bets.
thats it!!
About the size I prefer it to be as big as possible, those keys and displays of the big and cheap claculators work perfectly. That in order to avoid typing mistakes and clearly see the result.
About the budget, I dont think it would be expensive as a weekend project. You know, I´m the kind of guy who likes to build stuff from ¨junk¨ and re-used parts, as a mechanical it works real good for me, I just don´t know how that idea fits in electronics.
Bottom line is that I don´t want to buy real expensive parts to build it, but I can spend a few dozens of bucks as a personal project.
Thanks a lot
Well... re-using or recycling electronics parts can be a time consuming task.
Step one is disassembly of course, then you need to ID the parts and either remove them or modify the circuit to do your bidding... This is not always easy and the step required could vary wildly from one calculator to the next. So if you want it to be a weekend project, I would certainly suggest you either buy new parts, or you find/buy equipment you *know* you can hack/salvage.
I'm confident that the guts from any/all calculators will be useless, but depending on the calculator you find, you may be able to re-use the keypad and/or display. This is going to depend largely on the type of display and the type of keypad used and may require some tinkering and engineering work to connect to a third party device to do what you want. Keep your eyes open for the accounting style calculators that use LED segments for the display instead of those cheap, flat, LCD displays. They will most likely be easier for you to work with.
Anyway, let's explore buying new parts, and what to expect with costs.
Your keypad does not seem to require any more buttons than 0-9 and maybe decimal and clear (or backspace) because this is a purpose built machine that only does division.
Something like this perhaps :
https://www.adafruit.com/products/419
* can be the decimal, and # can be the backspace (or hold for clear)
This can control the LEDs you find/buy:
https://www.adafruit.com/products/1427
Maximum of 16 digits per controller.
LEDs can be found here:
https://www.adafruit.com/products/811
(Various colors available. Sections of 4 numbers.)
Then you need a microcontroller, and some miscellaneous resistors and a couple caps perhaps. (Oh! and a power supply)
Total cost if you want to build it from new parts would probably be in the order of $70-$90 USD *if* you got the parts from adafruit. This would include an Arduino microcontroller, a pair of LED controllers, 6 sets of 4 character LEDs giving you 8 characters per display, and a pair of keypads.
You can also buy parts from other suppliers if you find them cheaper.
This is very rough work, but outlines what you would need. The real tricky part for you will be finding something you can reprogram. It would be best if you at least buy a microcontroller, then you can add onto it as you find used/recycled parts.
