Bulding an RPN Calculator
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03-23-2019, 12:51 AM
Post: #1
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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, Pedro |
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03-23-2019, 02:53 AM
Post: #2
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RE: Bulding an RPN Calculator
Yes, of course - more please!
Jack http://www.computerarium.org |
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03-23-2019, 03:57 AM
Post: #3
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RE: Bulding an RPN Calculator
Yeah. This is rather cool! I would love to hear more, especially with what you are going to do with the keyboard layout. And...
Welcome to the Museum! |
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03-23-2019, 05:19 AM
Post: #4
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RE: Bulding an RPN Calculator
Nice project.
Are switches a possibility? The tactile feedback is worth a lot (to me). I worked with someone who soldered one of those flex sheets to fix an HP 30B of mine. I'd have ended up with a blob of plastic (if I managed to avoid vapourising it). Have fun with the software! Pauli |
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03-23-2019, 06:50 PM
Post: #5
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RE: Bulding an RPN Calculator
Brilliant and welcome aboard! Yes, please do keep us posted.
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03-26-2019, 01:58 PM
Post: #6
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RE: Bulding an RPN Calculator
Not at all Pedro, in fact, quite the opposite. Please keep posting progress on your RPN calculator. Wishing you much success!
Eddie |
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03-26-2019, 04:54 PM
Post: #7
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RE: Bulding an RPN Calculator
(03-23-2019 12:51 AM)pcardoso73 Wrote: At this point the calculator is not yet assembled, but the arduino, keyboard and lcd are working. More details, please! Also, does that = key work as ENTER now? Tom L Cui bono? |
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04-02-2019, 10:20 PM
Post: #8
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RE: Bulding an RPN Calculator
Hi,
Thank you all for your kind words. Quote:Also, does that = key work as ENTER now? Actually the key which will be the ENTER is the big + key. I thought that the ENTER should be large, hence the choice. Regarding the development, nothing happened this week. Today I received a hot glue gun and a set of metal files. I have ordered the files since the calculator's case doesn't close where the LCD is. Fortunately, it has some slots that can be filed down. Then I will use hot glue to put everything in its proper place. But before closing the calculator, I will have another problem to solve:
The last reminds bullet makes me laugh, because it reminds me when I opened the calculator for the first time. Despite saying that the calculator is dual powered, the solar cell is fake and instead, they put inside a coin cell. :-) Soon I will post some more photos and details. Thanks. Cheers, Pedro |
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