Subject:
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Re: LEGO Electro-magnet
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 15 Apr 2001 16:17:04 GMT
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Viewed:
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1640 times
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James Matthews <lego-robotics@crynwr.com> wrote in message
news:MABBKIIIBOMODJGILHECOELFCDAA.generation5@btinternet.com...
> Thanks it worked! I had some magnetic wire from a Stiquito set I just • built,
> to I managed to get a simple one working, but I couldn't connect it to the
> RCX for some reason. I'd attach it to one of the LEGO wires (do the order • of
> the connectors matter?) and it didn't work - but about 30 seconds later • the
> RCX would turn off, beeping wildly and complaining about the batteries
> (little battery icon with a cross through it).
>
> Any pointers? Thanks for the help so far.
>
> James.
I had the same battery warning when connecting some large non-Lego motors to
my RCX, and I'm fairly sure the reason is just that they draw too much
current. The Lego motors normally operate at a maximum of something like
250-350mA, and I guess the electromagnet has much lower resistance and so it
uses a much larger current. This might damage the RCX, but it probably has
some kind of internal protection which just causes it to turn itself off.
All you can do is use a longer piece of wire -- to get 9V running at 350mA,
the wire needs a resistance of about 25 ohms.
--
Philip Taylor
http://robowarriors.lego.ultrastore.com
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Message has 1 Reply:
 | | Re: LEGO Electro-magnet
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| Hi all, there is another thing you should think about. When using an electo-magnet, you use a coil. This coil stores energie, so if you switch it off, the coil gives this energy free. (This is the energy your ignition-sparks gets from an ignition (...) (24 years ago, 15-Apr-01, to lugnet.robotics)
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Message is in Reply To:
| | RE: LEGO Electro-magnet
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| Thanks it worked! I had some magnetic wire from a Stiquito set I just built, to I managed to get a simple one working, but I couldn't connect it to the RCX for some reason. I'd attach it to one of the LEGO wires (do the order of the connectors (...) (24 years ago, 15-Apr-01, to lugnet.robotics)
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