Re: "plug in" power for HP 41 Message #2 Posted by Ellis Easley on 21 Apr 2002, 9:31 p.m., in response to message #1 by aruid
Tony Duell said there are two versions of the rechargable pack - one has a voltage regulator that applies no more than 6 volts to the NiCads, the other just has a limiting resistor and would produce a higher voltage if the NiCads opened up. Since the NiCads are soldered in, there isn't the same risk of an open circuit as in the Spice and Woodstocks. But what I have considerd doing (haven't done it yet), since my rechargable pack, which I got in non-working order, has the voltage regulator, is to use the pack without NiCads just to run the calculator from the line, as you suggest. My pack has a rectifier, filter cap, a TO-92 12 volt (I think) regulator, a resistor, and a 6 volt zener diode. Adding some large electrolytic caps, maybe some approximately 1 farad "supercaps", in place of the NiCads might even keep the memory without AC for some time (if you are very careful not to turn on the calculator!)
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