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Bulding an RPN Calculator
03-23-2019, 12:51 AM
Post: #1
Bulding an RPN Calculator
Dear all,

As all of us, I am an RPN and hp calculator lover. My day to day calculator is an HP 48G, but now I need something larger with big keys (aging vision problems, so big keys = big letters and numbers).
After searching a bit, I could not find a big RPN calculator. So, in order to get a big, inexpensive RPN calculator, I would have to build one. Cool !
I started by looking for the perfect calculator. It must be thick enough to fit hardware inside and large enough so could have big keys.
I ended up and buying a 5£ desktop calculator off eBay. The idea was to strip everything inside, replace the original LCD by a two-line LCD and control everything with an Arduino. :-)
In the beginning I thought that I would touch only the LCD (single line and 12 digit and I needed two lines) and keep all the rest, but things didn't go that way.
The keyboard is a simple membrane keyboard. Unfortunately, the acetate sheet that has the tracks painted is glued to a pcb (not soldered), so it is not reusable. When trying to remove it, it became unusable.
Because of this I made a PCB for the membrane keyboard and it works! :-)

Until now, these are the materials used for this project:
1 Desktop calculator
1 LCD 24 x 2 display
1 Arduino nano
1 Custom PCB
1 battery (to be decided, but I might use a single cell powerbank).
and lots of wires

At this point the calculator is not yet assembled, but the arduino, keyboard and lcd are working.
If you like, I can give your more details as the project progresses.
I hope this post wasn’t too boring. ?
Best regards,

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Messages In This Thread
Bulding an RPN Calculator - pcardoso73 - 03-23-2019 12:51 AM
RE: Bulding an RPN Calculator - jackrubin - 03-23-2019, 02:53 AM
RE: Bulding an RPN Calculator - Carsen - 03-23-2019, 03:57 AM
RE: Bulding an RPN Calculator - Paul Dale - 03-23-2019, 05:19 AM
RE: Bulding an RPN Calculator - BobVA - 03-23-2019, 06:50 PM
RE: Bulding an RPN Calculator - toml_12953 - 03-26-2019, 04:54 PM
RE: Bulding an RPN Calculator - pcardoso73 - 04-02-2019, 10:20 PM

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