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From: "Tom Doolittle"
Subject: Making a battery backup for an AC adapter
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
NNTP-Posting-Date: Mon, 02 Sep 2002 23:46:04 GMT
Organization: AT&T Broadband
Date: Mon, 02 Sep 2002 23:46:04 GMT
I have a home electronics project that I was hoping to get a little help
with. I have a battery operated toy (a Lego RCX programmable brick - part
of Lego's Mindstorm robotics set) that allows you to code simple robotic
programs on your computer and download them to the programmable brick via an
infrared connection. The particular version of the programmable brick that
I have operates on DC power (6 AA batteries, or 9V of power) and does not
have an AC adapter. However, I need it to run off of an AC adapter so the
batteries don't constantly go dead. I've managed to rig the unit so that it
runs off a 12V AC wall-wart adapter (I used a voltage regulator to get the
power to a consistent 9v), so I have that part of the problem solved.
However, the problem that I have now is that I need to be able to move the
programmable brick from an AC outlet in one part of the house to an AC
outlet in another part of the house. This is a challenge since the
programmable brick stores the downloaded programs in RAM, which is erased as
soon as the unit is unplugged, which means that when I plug the unit in
again, the program has been erased and the programmable brick is pretty
useless : (
So what I want to do is make a temporary battery backup from a 12V camera
battery (or some other type of battery pack) so that I can unplug the unit
for a minute, have the programmable brick run off of battery power for a
minute while I move it to another AC outlet, then plug the unit back in and
have the power switch back to the AC adapter. This will allow me to move
the unit from room to room and not have the RAM erased.
I'm not an electrician or an engineer, but am capable of figuring most
simple electronics out (at least I think I'm capable - I could be wrong : ).
So I have a conceptual idea of what I need to do, but am not sure how to
make it work from a practical standpoint.
I have drawn some simple diagrams that I hope illustrate the problem and
would be grateful for any suggestions. The diagrams are here:
Thanks alot for any help,
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