Re: cheap power for the HP41C (while at desk with cardreader) Message #2 Posted by Diego Diaz on 6 May 2011, 9:34 a.m., in response to message #1 by exschr
Hi,
As long as you have a USB port handy (or any other stable power source for that matter), there's no need to be messing around with external D-cells, adaptors or anything else.
In fact you don't even need the 41's N-cell battery pack in most cases, (see note on Halfnuts)
Just a standard USB cable (preferable not too long), and an empty ROM module with a good connector.
- Cut the cable to an appropriate length.
- Identify the +ve and -ve wires.
- Solder the Positive wire to the module's BAT (upper right connector pin, front view -see below-)
- Solder the Negative wire to the module's GND (the upper third one, right to letf -see below-)
GND BAT
--------------------------------------
| - - - - - - |
[ - - - - - - ]
------------------------------------
Module's front view
Hope this helps.
Diego.
NOTE on Halfnuts: Due to its internal circuit design, Halfnut may show the BAT annunciator permanently ON, with the power arrangement described above, if no battery pack is present; and will more likely fail to operate the Card Rader showing the "LOW BAT" message on the display. Normal operation will perform as expected though (even if no battery pack is present)
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