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 17:17:22 GMT
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Viewed:
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1689 times
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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 coil in your car). This might damage your RCX. You should use a diode
(1N4007 for example) to unload this energy. Attach the diode in the
blocking direction. Now you have to be sure to attach it the right way. (Or use
another diode in series to proof right connection).
We used such a magnet in a contest. Look here for the Drops collector :
http://www.informatik.fh-hamburg.de/~lego/Projekte/projekte_englisch.html
(We used the magnet of a 6V Finder relay, which was able to hold a 500g hammer
with a current of ca. 30mA)
Rainer
In lugnet.robotics, Philip Taylor writes:
>
> 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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| Rainer Balzerowski <balze2@gmx.net> wrote in message news:GBuG0y.EAv@lugnet.com... (...) electo-magnet, you (...) gives (...) diode (...) (Or use (...) hammer (...) Because motors also contain electromagnets, I imagine they would have the same (...) (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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| James Matthews <lego-robotics@crynwr.com> wrote in message news:MABBKIIIBOMODJG...net.com... (...) built, (...) of (...) the (...) I had the same battery warning when connecting some large non-Lego motors to my RCX, and I'm fairly sure the reason (...) (24 years ago, 15-Apr-01, to lugnet.robotics)
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