Disclaimer for this guide is that – we have not tested them. We are presenting the schematics, parts, circuit diagrams, codes for building DIY 7 segment LED display calculator which includes Arduino project. From their quality of presentation of schematics, it is almost obvious that attempt will not fail.
DIY 7 Segment LED Display Calculator : Some History and Technical Part
Before pre-built calculators were available, kits were sold exactly like DIY kits sold now. Those hardware and softwares are also emulated now. Most of these are programming calculators.
Keypad used usually push button switches. There is one somewhat known project named Kim UNO. That Kim UNO’s PCB is available as ready to use keypad and display, like SpikenzieLabs Calculator Kit. However the later is about $60 with shipping charges.You will get old used LED calculators on Ebay at 10-$15 price. CASIO FX-120 scientific calculator will cost $15 to $27. They are basically good at least for the case.
DIY 7 Segment LED Display Calculator : Schematic and Code
Our choice is this one (see photo in this guide) :
The PCB design is also given clear manner.
Next choice will be slash number calculator :
Next choice will be Kim Uno :
Next is a project which used kind of Kim UNO but full sized Arduino :
Next is an Arduino Shield (technically great) :
I am not sure where that where the Arduino Calculator Shield is easily available for human all over the earth at this moment. I guess that should be the end story of Arduino Calculator in future.