|Or, you could do what I did...|
Message #6 Posted by Jeremy on 30 Mar 2003, 7:56 p.m.,
in response to message #1 by Gary Smith
Which is to hardwire a AAA battery holder to the circuit board. Then, you can use alkalines, Ni-MH rechargables, Ni-Cad rechargables, etc. and you don't even need to have the HP charger or equivalent. It seems to me that the risk of blowing up the calculator because of a simple mistake of plugging the charger in w/o a good battery pack in place is an accident waiting to happen. Going from AA to AAA you do lose some battery life, but you never have to jerk around with the charger again unless you want to...
Do you have the charger? If I had the charger, I would:
1. Buy a battery pack for a cordless phone that is made of 2 AA Ni-MH cells. (again, at Radio Shack or equivalent)
2. Cut the wires of this battery pack right next to the connector and throw that connector out.
3. Neatly solder a 9V battery connector to the leads you just exposed. (you guessed it, the 9V connectors are available at Radio Shack for < $2 for a pack)
4. Hardwire another 9V battery connector to the points on the HP circuitboard where the battery terminals are wired to. (Make sure you attach it with the polarity reversed. Since you're hooking two of them together, it will switch to polarity when you plug them together)
5. Run that connector into the battery compartment.
Now, when you want to replace the battery pack again, (10 years from now?) all you have to do is buy a cordless phone battery pack, and replace its connector with a 9V connector and you're ready to rock. Of course, that ruins the originality of the calculator, but it is more practical and lets you get 50% more life out of each battery charge, since they didn't have Ni-MH batteries in the 70s.
If you ever want to sell the calculator on eBay, you won't get a collector's sum for it, but you might get more bidders, since they won't have to also look for the !@#$ HP battery pack.