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I never liked the bulky shape of the TI-58/9. It was necessary for the 59's card reader but not for the 58. Opening it up shows a lot of empty space. So why not cut it out?

A kind forum member sent me some disused case backs and I applied a Dremel cutter and some wet sandpaper. I added a new clear bottom and a cell phone battery. It needs finishing, such as black paint around the edges. It's now only as thick as a TI-84 and I hope to use it as a daily driver, if the battery life allows.

Another example of a geek with too much time on his hands. [:-)

Where were you 30 years ago?

I love it! Very nice work.

Edited: 25 June 2010, 9:42 p.m.

Since it won't hold itself at an angle anymore, now all you need is one of those neat angled desk calculator holders EduCalc used to sell!

30 years ago I was programming my 2nd personal computer, a TI-59 (couldn't afford an HP). 1st was a TI SR-56, 3rd was an Atari 400 (couldn't afford an Apple II).

Besides, where were Lithium ion batteries 30 years ago?

Edited: 26 June 2010, 10:13 a.m. after one or more responses were posted

Very nice, I love it also. Keep us informed about battery life.

30 years ago I was programming my 2nd personal computer, a TI-59 (couldn't afford an HP).

I was programming a TI-59 myself, my first calculator/computer. A slimmer TI might have appealed to me back then...

Finally, the back is finished.

Pretty neat!!!! Congratulations!

Luiz (Brazil)

I wonder if that's possible with the 48G housing.


Nice job indeed. One tech question: Is the Li-Ion battery charger included into the calculator body or is the battery charged by a separate charger/device?

Cheers from Spain.


I use a broken cell phone to charge the battery. But yours is an interesting idea, if I can remove the charging circuit from the phone or find a small charger. Hmm, I thought I was done with this project!

The 3.7 V Li Ion battery does 850 mAh, which matches nicely the voltage and capacity of the old 3-cell NiCd packs from HP and TI. I don't know about the 48G, though.

In use, the battery does not get as warm to the touch as the 58's DC-DC converter.

Very nicely done!!!!!