Can TI SR-5x and TI-5x be run from AC with no battery?

[Maximilian Hohmann]

Hello!

(03-23-2023 09:20 PM)brouhaha Wrote:  Is it safe to run the TI SR-50/51/51A/52/56 and TI-58/58C/59 calculators from AC with no battery? Or do they have the design flaw of the HP Woodstock series, where the battery is necessary to limit the voltage and avoid damaging the PMOS chips?

Just today I received a Ti SR-10 in the mail (the first "scientific" calculator from Ti from 1972) and the manual explicitely warns against powering it with the wall charger when no battery is in place, otherwise "damage may occur".

In the past I did occasionally power my Ti59 without a battery and it just wouldn't work properly. The display flickers and the card reader can't read cards. So far these attempts did not damage the calculator permanently, but I will never try it again.

If you have no (working) battery the safest way to power these calculators is a PC-100 printer. Different form the wall charger, it supplies a regulated voltage.

Regards
Max