HP-41C: +3V inner battery contact


Hi everybody,

I would like to know if the +3V inner battery contact of the 41C is used by internal circuits. Can it work with +5V? Thanks!




If you are mentioning the middle point between the four batteries, the contact is not used inside, it is just a bridge. The rechargeable battery pack does not have any points there, and the earlier HP41 calculators had a pair of contacts that allowed the calculator to be powered with external source. The schematics provided in one of the threads will give more info.


Luiz (Brazil)



About the 5Vcc, the HP41 works with 5Vcc somehow because you can use four N-size rechargeable batteries (aprox. 4.8Vcc nominal). Back to the first question, please read this thread and you'll find the link to the schematics. Check and you will see that the batteries are drawn as +Vcc and -Vcc.


Luiz (Brazil)


Hi Luiz,

Thanks a lot for your tips. I saw the schematics and the information inside is useful.


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