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Author Topic: Use a brushless PC fan to make an Electomagnetic Field with no moving parts  (Read 2543 times)

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DoubleD

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Is it possible to make an electromagnetic field using just the bottom end of a PC brushless fan motor?

I took the Fan blades (with permanent magnet) off of a 12V  brushless motor. Using an EMF detector I applied 9V to the the bottom end of the motor (Stator and controller only)  and I got a quick short burst of EMF.

I know nothing about electronics but the electromagnetic field was not sustained. I assume it was because the rotor was missing the rotor and there was nothing to trigger the hall effect sensor to kick the other coils.  ( I read a little about brushless motors http://pcbheaven.com/wikipages/How_Brushless_Motors_Work/). I noticed that if I pulsed the power then EMF was sustained.  I also assume that only one (maybe two) of the 4 coils were actually being used generate the EMF.

Is it possible to bypass the hall effect and make this stator produce EMF, powering up the coils in a continuous circular round robin rotation?

Any direction is appreciated.


kam

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Hello. Yes you can indeed make an electromagnet a small one. Just ripp off the pcb completely. Then you have 4 electroagnets each one with 2 wires. Chances are that they are connected in series in pairs o 2 opposite ones. Find which 2 wires are comming from one electromagnet (or one pair) and apply power. You will have an emf as long as you apply power.

DoubleD

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I thought about that too. The wires are so thin I'm sure I'd mess it up that is if I could see the ends :)


Correct me if I am wrong but this approach would only power up two of the four electromagnets.

I was hoping to alternate between the magnets using the hall effect sensor but not the rotor magnet


kam

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what exactly you want to do? make a rotating electromagnetic field? If yes, then you definitely need to make a controller yourself. And most likely it has to be a SIN wave controller to have a smooth EMF rotation, exactly as it happens in 3-phase motors.

DoubleD

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Yes  make a rotating electromagnetic field and if I could speed it up or slow it down that be a plus

I guess its much more involved than I thought - I guess I'll stick to keeping the rotor and I'll snap off the fan fins

kam

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Yes it is harder than plugging in a BLDC. Even if it works, that would not be a rotating field, instead a 4-phase pulsing one.
3-phase motors generate a smooth rotating field.

DoubleD

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Maybe I'll try this http://homemadecircuitsandschematics.blogspot.com/2012/05/make-this-emf-pump-circuit-and-go-ghost.html


I'm just not sure of all the wiring or how to make the coils - I guess I could try to use the coils from the fan since they look to be the same