Make a retro scientific calculator with LED display and mechanical keypad.

Make a retro scientific calculator with LED display and mechanical keypad. - Printable Version

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Make a retro scientific calculator with LED display and mechanical keypad. - geekvan - 04-11-2023 11:05 AM

Hi Guys, for several years, I am seeking a scientific calculator with a big screen and keyboard and never found one, so I decide to make a retro one. the simple way is using a calculator ASIC and connecting it to LEDs and a mechanical keypad. Unfortunately, there are too few chips with LED output directly, so I should make a LCD to LED converter first. After doing the first test, it runs OK. It's not an emulator but a "real" machine. Here is the prototype of the calculator with the original PCB. The next step is to integrate all the parts into a whole PCB, and add mechanical keys, wish you like it.

and here is a short video:

RE: Make a retro scientific calculator with LED display and mechanical keypad. - dm319 - 04-14-2023 06:02 PM

That's pretty nice. Maybe add a macropad for the keys. Will it be RPN?

RE: Make a retro scientific calculator with LED display and mechanical keypad. - geekvan - 05-04-2023 03:11 PM

the 1st integrated pcb worked finally.

https://flic.kr/p/2oxYuAn

RE: Make a retro scientific calculator with LED display and mechanical keypad. - toml_12953 - 05-05-2023 02:49 AM

(05-04-2023 03:11 PM)geekvan Wrote: the 1st integrated pcb worked finally.

If you ever sell a kit, I'm in!

RE: Make a retro scientific calculator with LED display and mechanical keypad. - geekvan - 05-08-2023 09:13 AM

(05-05-2023 02:49 AM)toml_12953 Wrote:
(05-04-2023 03:11 PM)geekvan Wrote: the 1st integrated pcb worked finally.

If you ever sell a kit, I'm in!

Thanks, but I'll make this project open and won't sell it.

RE: Make a retro scientific calculator with LED display and mechanical keypad. - geekvan - 05-13-2023 10:46 AM

here is the final prototype without enclosure.

https://www.youtube.com/shorts/Iv_z6_ydeSI

all the sources can be found here:
https://github.com/geekvan007/retro_sharp506

RE: Make a retro scientific calculator with LED display and mechanical keypad. - EdS2 - 05-13-2023 01:53 PM

Very nice indeed! Does the calculator chip have to come from a salvaged calculator?

RE: Make a retro scientific calculator with LED display and mechanical keypad. - geekvan - 05-13-2023 02:36 PM

(05-13-2023 01:53 PM)EdS2 Wrote: Very nice indeed! Does the calculator chip have to come from a salvaged calculator?

Yes, The chip named SHARP-LI3301A from last century.
Thanks!

RE: Make a retro scientific calculator with LED display and mechanical keypad. - EdS2 - 05-13-2023 03:03 PM

Aha - looks like quite a few manufacturers used that chip (Edit: but these are programmable, which is confusing me):

Quote:Used in: ASTOR: 2, ATABA: AT687, AURORA: TB607, CANON: F300, CITIES: 8700, CITIZEN: SRP145, CITIZEN: SRP40, DYNA-TONE: G3/8700, IBICO: 098, INTERTRONIC: SC88P, KNIGHT: K31A, MBO: 610PR (version-1), MBO: 820PR, PIRACOMP: PR40, PIRACOMP: PR80, PRIVILEG: LC650PR, RADIO SHACK: EC4021, RADIO SHACK: EC4036, WHIRLPOOL: CW201

Also apparently Levis and Shangji.

Edit: is it the 42-key SHARP EL-506P we need? I see there was a 506A and 506H too, with different number of keys.

If so, there's a list of 20 clones here.

Edit: this is confusing!

Quote:With the replicas of the chip used in EL-506P, the first „clones” was built in similar housing as used in EL-506H, at various factories in Hong Kong, Taiwan and China. Later, with similar appearance and same model number, a simple programmable calculators based on a genuine Sharp chip — which was made for Sanyo — completed.

RE: Make a retro scientific calculator with LED display and mechanical keypad. - geekvan - 05-13-2023 03:56 PM

(05-13-2023 03:03 PM)EdS2 Wrote: Aha - looks like quite a few manufacturers used that chip (Edit: but these are programmable, which is confusing me):

Quote:Used in: ASTOR: 2, ATABA: AT687, AURORA: TB607, CANON: F300, CITIES: 8700, CITIZEN: SRP145, CITIZEN: SRP40, DYNA-TONE: G3/8700, IBICO: 098, INTERTRONIC: SC88P, KNIGHT: K31A, MBO: 610PR (version-1), MBO: 820PR, PIRACOMP: PR40, PIRACOMP: PR80, PRIVILEG: LC650PR, RADIO SHACK: EC4021, RADIO SHACK: EC4036, WHIRLPOOL: CW201
Also apparently Levis and Shangji.

Edit: is it the 42-key SHARP EL-506P we need? I see there was a 506A and 506H too, with different number of keys.

If so, there's a list of 20 clones here.

Edit: this is confusing!

Quote:With the replicas of the chip used in EL-506P, the first „clones” was built in similar housing as used in EL-506H, at various factories in Hong Kong, Taiwan and China. Later, with similar appearance and same model number, a simple programmable calculators based on a genuine Sharp chip — which was made for Sanyo — completed.

It seems that the chip LI3301A is used for OEM manufacturers only. All SHARP calculators that use this chip are clones (fake). I bought many used calculators with this chip that have different suffixes, including 506P/506H/514.

Also, I heard that this chip has a clone one which was made by a Vietnam company.

RE: Make a retro scientific calculator with LED display and mechanical keypad. - Garth Wilson - 05-13-2023 09:35 PM

I sure like those keys.

RE: Make a retro scientific calculator with LED display and mechanical keypad. - TallKey - 05-13-2023 11:34 PM

Looks great and thanks for sharing your project.

But one feature is distracting and it is the blue LED MEM indicator.

RE: Make a retro scientific calculator with LED display and mechanical keypad. - bwiese - 06-18-2023 04:35 AM

Geekvan,
Who's the source of your keytops? And standard Cherry keyswitches?

Bill

RE: Make a retro scientific calculator with LED display and mechanical keypad. - geekvan - 06-19-2023 02:53 PM

(06-18-2023 04:35 AM)bwiese Wrote: Geekvan,
Who's the source of your keytops? And standard Cherry keyswitches?

Bill

Hi Bill,

keytops were bought from China Taobao: blank xda and printed xda number keys.

https://item.taobao.com/item.htm?id=676692151586
https://item.taobao.com/item.htm?id=685502367565

and the key is compatible with Cherry MX.