Re: tv cheater cord and a six volt battery! Message #10 Posted by Christoph Klug on 9 Sept 2009, 2:35 a.m., in response to message #9 by Egan Ford
Dear Egan,
Please refer to I/O-Board manual Chapter XIII.07
In Chapter XIII I describe a small circuit which activates HP41 by an extern signal (galvanic isolated with help of an opto coupler).
In Chapter XIII.07 I modify the HP41 battery holder with a small +6V backup battery and an 5 pin terminal for external DC supply. I add an micro switch for selecting internal backup battery or external DC supply. The micro switch is activated when the external cabel /harness is pluged in ....
This extenal Dc supply application is helpful for long time interface applications - and for advanced interface applications which need an wake up of the handheld by an external event - and last not least I use the external DC supply when burning ZEPROMS...
Best regards - Christoph
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