| Gallery, Projects and General > How do I?? |
| electromagnetic project |
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| John Hill:
I think the dimmer idea is OK in as much as that is likely to be the least of the challenge. If you want to make a variable electro magnet then yes you can plug your simple rectifying power supply (i.e. DC power pack) into a lamp dimmer and you will get variouable strength of the electromagnet. But I am having problems visualising the magnetic circuit of what you are trying to do, can you confirm this is a 'blanket' and not just a string of beads you are trying to control? |
| jake598:
John Hill, It will be a membrane of tightly woven beads so that it can cope with the flexibility of changing shape. I have seen there are a few types of electro-magnets. Would you have an idea of what to purchase, and the amount of force on it needed to achieve what I am am trying to do. Thanks a bunch for your help. |
| picclock:
Hi Jake I don't think the dimmer approach is likely to work - especially over the 12" 50cm distance you require. If you just want to control it with a knob have you considered using another magnet with a rack/pinion drive. This would allow you to turn a knob, raising or lowering the controlling magnet as required. If it needs to be controlled electrically you could use a stepper motor to do the raising/lowering. Controlling an electromagnet which could lift the weight of your 'blanket' to a height of 50cm will create real issues, especially to anyone with magnetic material standing near. Good Luck Best Regards picclock |
| HS93:
also keep people with pacmakers as far away as possable. Peter |
| BillTodd:
--- Quote ---Rather than a 'sucking' type magnet I am after a 'pushing' type (i know that isn't the right terminology). --- End quote --- I think you need to do a little research... :wave: A magnet will only repel a like pole of another magnet i.e. a north pole will repel a north pole. Unfortunately, magnets always have two poles; There are no magnetic monopoles in nature. A magnetic field will normally only strongly attract ferromagnetic materials e.g. Iron, Nickel and their compounds. There are a couple of odd exceptions: One is the special state of Super-conductivity. In a super-conductor, the electric currents induced by the external magnetic field will produce an opposing magnetic field, so producing an opposing force between the magnet and superconductor. The other is a weak force called Diamagnetism. Some materials (e.g. water) can produce a weak opposing field in the presence of a strong magnetic field (enabling a crazy scientist to float a tiny frog in a bead of water, placed between the poles of a very strong magnet see - http://en.wikipedia.org/wiki/Diamagnetism) In effect this means your electro-magnet will always attract your beaded material. Bill [edit] Another approach to 'floating' on a magnetic field is to use an AC field to induce a field in a non-magnetic conductor For instance you can use an AC electro-magnet to lift an aluminium sheet. The problem here is the induced current in the aluminium will heat it considerably, and the force of the field drops with the square of the distance. |
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