How do you like the Woodstock calculators?

[Steve Simpkin]

I used my HP-25 for almost 10 years as my only calculator through high school, 4 years of collage and 2 years at my first job as an electrical engineer. I too never gave charging a second thought although I never plugged the charger in without a battery pack installed. Around year 8 or 9 the batteries would no longer hold a charge and I switched to using alkaline batteries. I was concerned about the higher voltage from using alakalines so I cut the battery springs apart and soldered a silicon diode between them to drop a the voltage a bit. This seemed to work ok but around a year later, I started experiencing glitches in its operation. I ended up replacing it with a new HP-11C. At some point I removed the diode and soldered the spring back together and it has been working happily on alkaline batteries ever since. I suspect the diode was dropping too much voltage or it’s series resistance was too much. The 0.5 higher voltage from using alakalines does not seemed to have harmed it.