[Robotgroup] electromagnets

[brooksdesign]

that reminds me....I have an old rotted out hammond organ that the only still useable parts left are a whole bunch of coils of a couple of different gages of magnet or resistor wire .I have not pulled the whole thing apart yet but there seems to be a lot of it .
  Also ,does anyone have any fabric reinforced hose like fire hose matireal ?
-brooks

-----Original Message-----
>From: Gray Mack <gray_mack at yahoo.com>
>Sent: Oct 13, 2006 5:53 PM
>To: Austin Robotgroup Mailing List <robotgroup at puremagic.com>
>Subject: [Robotgroup] electromagnets
>
>It sounds like some of us are interested in projects
>involving electromagnets. It seems we don't really
>know much about them. 
>
>Here are some websites I found:
>
>http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/solenoid.html
>
>http://www.ndt-ed.org/EducationResources/CommunityCollege/MagParticle/Physics/ElectromagneticFields.htm
>
>But there is still a lot of unknown things when it
>comes to creating motion with electromagnets.
>It will take some experimenting to figure out what can
>be done with them.
>
>Many questions arise about how strong they can be, how
>much current they draw, how they respond to signals
>such PWM or alternating current, how opposing coils or
>magnets can be used to increase the pull capability
>and provide push capability and how to mechanically
>amplify the motion created since the field strength
>dissipates rapidly with distance. 
>
>How does the effort and cost of winding our own coils
>compare with buying commercial solenoids for a project
>that might contain 10, 100, or 1000 coils?
>How do the parameters the coil (# of turns, height,
>radius) affect the distance that it can push/pull a
>magnet?
>
>Some goals could be:
>*making paper butterflies wings flap
>*controlling steel balls on a table
>*creating a tabletop caterpillar robot that moves by
>pushing small angled feet a tiny distance
>*changing the height of an array of tiles making up a
>table
>*assisting pendulums in an art sculpture to swing so
>they don't stop due to friction
>*Cause mirrors to move that reflect laser light in a
>pattern.
>*using the feedback from an optical sensor to keep
>just enough field strength for levitating a metal
>object 
>*Interacting with ferrofluid made from printer toner
>and oil
>*Play a musical instrument by controlling valves or
>causing percussion or vibration
>
>
>Cool things about electromagnet coils:
>*Cheaper than servos
>*Can last much longer than servos
>*Can move things quietly
>*Can be sized to the object they are in or drive push
>rods or cables
>*Can be used to generate push,pull, or rotational
>movement
>
>Problems:
>*Use lots of power
>*Must remain energized to maintain motion
>*Need a mechanical (spring,gravity,etc) return due to
>residual magnetism
>*Field strength dissipation allows for only small
>movement of actuator
>
>
>-Gray
>
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