HP82143A Powering a 41 _Extend Your HP41_

[Diego Diaz]

Hi all,

And thanks for your enthusiasm and your kind words.

To cover the original post question, at first glance the schematics in the 82143A service manual does not show any evident way for the Printer battery that can provide power to the HP-41.

The Vcc line is connected to the port, and Q3/CR1 connect it to Vp (5v) for the internal logic circuits in the Printer; but this won't provide any usable voltage for the bipolar power supply IC in the calculator and the BAT line isn't even wired in the connector.

I don't have an 82143A with me to check any further, but this statement seems to be either an error or a feature in some early Printers that was later removed.

Regarding the new power pack design, the lack of BAT annunciator is my main concern currently.

Not that this will render the unit useless but it will be great to have it back, so I'm working on a couple of mods that may recover such function.

Limited real state in the battery well is indeed challenging to include more components; but hey! if won't be funny if it was easy. ;-)

All the best.

Diego.