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# Coil + magnet = power source Answered

People, I need your help! I'm a student at college and my primer subject is physics. Let's just say I know enough about electricity and power. But my major obstacle towards constructing stuff is electronics. I have only just scratched the surface of it. I want to make a power source out of a coil and a magnet inside (electrical induction). Can anyone point out how exactly to build the thing? My desired output voltage is about 5V, or sth. I'll use it for electronics, so the amperage doesn't really matter. I would also like to see a circuit that converts AC to DC, cause the coil will give out only AC and that's not good. Thanks in advance!

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## Discussions

Use a crystal!

https://en.m.wikipedia.org/wiki/Rectifier

hey im only 15 but i really wanna make a coil torch. i already own one but want to consider making more out of old wires and make them more powerful. just one problem. im having trouble gettin the wire out of ol cords. any suggestions please???

The wire in cords will be un-insulated, and useless for your purposes. Better just by a reel of new insulated wire and wind your own.

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9 years ago

The voltage depends on how fast you move the magnet and how many turns there are on the coil, it's not easy to work out what voltage you will get for a given device because it depends on the magnetic field strength of the magnet as well.

How are you planning to move the magnet? A hand crank, water/wind turbine, bellows in your shoes?

I suggest you start making coils, moving magnets past or through them and measuring the output voltage (preferably with a needle voltmeter, they tend to respond faster than those yellow digital multimeters) to get an idea of how your planned device will work.

The simplest device to convert AC to DC is one diode, but that wastes half your power. The slightly more complex circuit is a rectifier which uses four diodes- see the first and second circuit diagrams here. If you can't read circuit diagrams I suggest you grab an electronics textbook and read it, they are vital for any serious electronics.

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9 years ago

check out circuit in one of those shake flashlights. Not 5 volts, but it's a start.

uhhh, just get wire with a small gauge, and then start coiling... The bigger the better...

get a neodinium magnet, those are strong and almost always used for this sort of thing. To convert AC to DC, you just need some diodes, which will have information on them, and you can add them together if you need more...

for voltage, just check with a multimeter when you're done, and then find out what you need.
I haven't really done much with generators, so i don't really have too much specifics.

AND, i'm just gong to say that a really EASY way to get one of these is just taking a normal electric motor, and using a crank instead of shaking it.

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10 years ago

Hey, this is very similar to what I need. But, can anyone point out how to make it bigger so I can get my desired output voltage of 5V?

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10 years ago

Asbestos, thanks for your comment. I am looking for a solution that includes one coil and one magnet. Kind of like that shaking hand torch thing. Like a tube with a magnet in it and a coil around it. Just like in a shake powered hand torch.

The Pringles Wind Turbine project, link, has a good wiring diagram. In general, you just need to move your magnet past your coil quickly, and rectify the current so that it's DC not AC.

You're not likely to get 5V out of one coil and one magnet, though, unless you move them very very fast.