At 01:25 PM 3/20/2007, David Mathog wrote:
> At 04:20 PM 3/19/2007, David Mathog wrote:
On further consideration, that common ground might be
a problem. On the one hand it's effectively running from one
serial port to another and generally that's ok. On the other
hand, if for whatever reason one or more of the grounds is
a volt or two higher than another one, that could result
in quite a current running on that signal wire. This would
probably be safer:
or use diodes. e.g. 1n5711 or 1N5401
Given that there is probably an alternate grounding path, you
probably want two diodes for each UPS (one in each line).
or, get a switch with 5 sets of contacts and use 5 sets of batteries
(I assume you were using Alkaline 9V batteries?)
James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875
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