Posted August 15, 2015
I opened one of my two HP 35s to check how the batteries are connected. I'm glad I did as I thought the two were in series making a total of 6V when they are in fact separate, i.e. two separate 3V DC power connection on the pcb. I might have damaged it if I would have connected a 6V (4 AAA or AA in series) supply like I planned to to replace the two CR2032 3V batteries. So I'm happy to have averted damaging the calculator.
Using normal batteries instead of button batteries will mean less trip to the battery store.
I like the HP 35s even if HP never updated the firmware (it has some significant bugs). My HP 42s does remain my favorite HP calc for the moment. I'm not a fan of the newer ones with a more BASIC like programming language (even if I have two og them). I do plan in the long term to make my own HP like calculator combining the old RPN programming language with a new graphic display.
Using normal batteries instead of button batteries will mean less trip to the battery store.
I like the HP 35s even if HP never updated the firmware (it has some significant bugs). My HP 42s does remain my favorite HP calc for the moment. I'm not a fan of the newer ones with a more BASIC like programming language (even if I have two og them). I do plan in the long term to make my own HP like calculator combining the old RPN programming language with a new graphic display.