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Full Version: RPN Scientific Firmware for the Spikenzielabs Calculator Kit
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(09-28-2017 06:46 AM)Alejandro Paz(Germany) Wrote: [ -> ]For like 14 € looks really good !

Just looked it up, the price actually is 10,59€ shipping included. One would have difficulties to buy the parts for that price. And I wouldn't know how to manufacture the laser-cut acrylic case.

This is the assembled (and working) calculator - next to a real calculator for size comparison. I didn't apply the labels and keycaps yet of course...

[Image: IMG13325_1024px.jpg]
Nice project!

Little OT.

(02-24-2016 08:48 PM)securd Wrote: [ -> ]Hi All,

I have always had a fascination with early scientific calculators, and I'm impressed by how the engineers in the 1970's did so much with so little. ...

to an Arduino port of the BigNumber arbitrary precision library, coded up high precision Taylor series approximations for the transcendental functions, and voila!

I agree that the engineers in 1970 did a lot. I also see that nowadays we do a a lot through libraries done by others.

Surely making a wrapper of a given library is not trivial, but doing everything by oneself would be a ultra challenge (and likely one won't have a final library as polished as the existing ones. At least not so quickly).

Old thread ... new developments :-)

The Chinese kit manufacturers came up with yet another calculator kit which might be the basis for DIY projects. This one comes with a 2x16 characters inverse backlit dot-matrix LCD screen and 20 keys, mounted in a very smart laser-cut acrylic housing with slanted display. Power comes from 2 2032 Lithium cells (not included in my kit). Why this one needs two cells as opposed to the LED calculator above which only needs one I don't know.

I assembled mine in less than two hours, there is not much soldering to do but cutting out the key labels and fiddling them into the keys takes some time.

Apart from being a basic calculator (no operator precedence or other smart features installed) it comes with three pre-programmed applications which are selected with the "mode" key: Calculate resistor values form their color code, calculate resistors required to operate LEDs and a simple HEX<>DEC converter.

Unfortunately this time they did not use an Atmega 328 processor (esily programmed in the Arduino environment with lots of resources awailable) but a chip called "15W413AS" about which I could not find a lot of useful information yet.

These are the bulding instructions: http://www.diyleyuan.com/jc/L8Q.html and below are some pictures of my kit and the finished calculaor. Maybe someone finds this interesting... Ah yes, I paid 11,95 Euros shipping included. Buying the parts individually would have cost more I guess!


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No Atmega, a bit of a shame. Nevertheless, thanks for sharing!
Judging by the key labels, it looks like its original purpose had to do with resistor color codes.
Nice. just bought two kits for $25 USD. Despite the lack of RPN, I could use a resistor color decoder and I love a cheap soldering project.
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