Hi Les,
The page I was preparing for my site was lost when my hard drive crashed. I'm confident I'll have it ready by the next week, but there are many applications and documents to re-install/restore, so I cannot tell for sure.
In the meantime you can find info on the USB-41 interface module (and about its current functional application) at:
this link for the last thread: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv021.cgi?read=216920#216920
this one for the previous note: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv021.cgi?read=212776
and this one to the manual and demo 82143A utility download: http://www.clonix41.org/Projects/USB-82143A/USB-82143A.zip
Also at a user's request I've extracted some relevant info regarding the USB-41 power features.
I'm still testing the many possible scenarios for powering the HP-41 using the USB-41 interface.
Here is what I've found so far:
-USB-41 can provide power undefinitely without batteries inserted, even when running a program continuously (tested for more the 24 hours) provided no other devices are connected.
-Halfnuts will always show "BAT" indicator when powered from the USB-41, but will also work as expected for as long as necessary.
-Some fullnuts also lite the "BAT" indicator. I've only found this behaviour in a few early HP-41C though. Again, they work as expected no matter how long they're running.
-Card Reader cannot be used without batteries, the "LOW BAT" message will appear in the display as soon as a card is inserted.
-Most units (including CL) can also run indefinetely with both USB-41 and NoV-64. Tested with a complete DISASM of the page #6 (-PRINTER-). Some, however, showed the "BAT" indicator.
Some other peripherals like the Wand and HP-IL may have different effect in the power usage of the 41 but as long as you use it without any other modules/peripherals you can have it
permanently connected and powered.
The USB-41 includes a Schottky diode so no power will "travel" back to the USB port from the HP-41. The other way around can be certainly possible, but since USB supplies 5v and the
diode drop is about 0.4v the batteries will havve to be below 4.6v (mostly depleted) to be "overpassed" by the USB power. Should this case ever happen it won't hurt the batteries either
since there is another internal protection diode in the battery line of the HP-41.
Hope this helps.
Best wishes from the Canary Islands.
Diego.
Edited: 14 Apr 2012, 6:20 p.m.