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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Wed, 18 Apr 2001 09:22:24 GMT
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Original-From:
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Mike Nardell <{miken@inetworld.}NoSpam{net}>
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Viewed:
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1524 times
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Another idea for a controllable magnet (one that could be turned on or off):
Machinists use magnetic bases to hold measuring instruments firmly onto the
steel ways of lathes and milling machines. The bases have a knob that
permits the machinist to turn the magnet on or off, making it easy to move
the base when the magnet is off and damn hard to move it when the magnet is
on. However it does not use an electro-magnet, rather it uses permanent
magnets which are rotated in or out of alignment to turn the force of the
magnet on or off.
Here is an experiment I tried moments ago to reinforce in my mind how the
thing works. Fortune had it that I had magnets on the refrigerator door, so
I took them (scattering coupons and adverts all over the place, oh well.)
The magnets were those small disks that Radio Shack sells (about 1.75 cm
Diameter, 0.50 cm thick) The poles of these magnets are on the faces of the
disk. Then I rummaged around my desk for something made of steel to pick up
( a razor blade), and a something made of steel to serve as the medium (a
paper clip). The medium allows the magnetic field to flow through it and it
is the thing that either holds or does not hold the razor blade, depending
on the orientation of the magnets.
Now if you place the magnets on opposite faces of the paper clip (making a
kind of magnet, paper clip, magnet sandwich), you will discover that the
paper clip will either pick up or not pick up the razor blade depending on
if the opposite poles or the same poles are facing each other. Well it has
been a long time since I have drawn ascii art, but here goes:
Magnet clip Magnet
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NS | NS
NS | NS
NS | NS
NS | NS
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--------------- Razor blade
Magnet clip Magnet
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NS | SN
NS | SN
NS | SN
NS | SN
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--------------- Razor blade
I will leave the info on which orientation holds the paper clip and which
does not for you to discover. I found it kind of fun to see how it worked
and I was surprised by the answer. But that may mean I am somewhat simple
minded.
It seems that it would be pretty easy to make something that does this trick
with Legos a bar of steel, and a couple of magnets. And of course there
would not be the battery drain problem found with the electro-magnet. I
think I may try something out tomorrow.
Thanks for the great idea of a Lego electro-magnet. Look forward to chatting
about this some more.
Regards,
Michael Nardell
> The easiest way to get an electormagnet is to hack a small 12 volt electric
> clutch or brake. These have a powerful electromagnet that still has good
> strength when run at 9 volts. Most of them will not overload the RCX. Edmund
> Scientific sells one, but I have not tried it.
>
> - pete.
>
> Pete Sevcik sevcik@flash.net
> Techno-stuff Robotics
> http://www.techno-stuff.com
> Robotics for FUN !
>
>
>
> James Matthews wrote:
>
> > Hi there,
> >
> > Being a *complete* dufus when it comes to things like electronics, I've no
> > idea how to start creating my own sensors, but I feel I have to start
> > somewhere.
> >
> > I've thought about creating a LEGO Electromagnet (uses the motor connectors
> > to be turned on and off) so you can create robots that pick up things. Any
> > ideas how I might go about doing this?
> >
> > Regards,
> >
> > James.
> >
> > - James Matthews
> > Generation5: http://www.generation5.org/
> > "...At the forefront of Artificial Intelligence..."
>
>
> --
> Pete Sevcik sevcik@flash.net
> Techno-stuff Robotics
> http://www.flash.net/~sevcik/
> Robotics for FUN !
>
>
>
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Message is in Reply To:
 | | Re: LEGO Electro-magnet
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| The easiest way to get an electormagnet is to hack a small 12 volt electric clutch or brake. These have a powerful electromagnet that still has good strength when run at 9 volts. Most of them will not overload the RCX. Edmund Scientific sells one, (...) (24 years ago, 16-Apr-01, to lugnet.robotics)
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