Re: HP 33E Battery Contact Polarity? Message #3 Posted by Les Wright on 9 May 2007, 9:37 p.m., in response to message #1 by Danny Eskenazi
Looking at the bottom of the calculator with battery cover off and top end of the calc away from you, he bottom left contact is positive. The upper left contact is negative. I tape two NiMH cells together and use an aluminum foil jumper to complete the circuit on the right hand side.
I wouldn't bother with alkalines. The NiMH cells will take a charge within the calculator (takes a while, mind you), and last quite a long time when they are fully charged.
Be careful when inserting and removing such a makeshift pack. The fit is snugger since the positive pole buttons are not recessed and make the batteries a little longer. My 33C has the positive contact broken off, but enough of a stub remains to complete the connection fine. The 34C has contacts intact but I am careful.
Mixing up polarity won't fry the unit but in continuous memory models it will discharge the capacitors and erase programs. I have done that a couple of times :)
Les
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