Mechanically-minded newbie has a silly question...

[cinco]

You've probably all seen the "Wasaby Sajado" videos with the computer cooling fan and the magnets, right? Well, a lot of people say it doesn't work, yada, yada, yada, but There is one thing that no one seemed to have a problem with, which I, not knowing anything about electricity, would have assumed was incorrect...so here's my stupid question...

Is it true that IF I can spin an electric fan(motor) by other means, then it will send electricity OUT, via its own power cord?

edited to add:

I should have said its wiring or wires - not necessarily its power cord. Also, I was just wondering maybe that's a DC thing? Like it wouldn't happen with an AC motor? I don't know.

To be honest, I don't really want a lot of detail as I find that knowing too many "facts" tends to cut off avenues of "new territory". Which is why I'm not actually "studying" electricity, as much as exploring it. Or, the less dangerous aspects of it, anyway. As I'm a bit of a sook when it comes to electricity. Which is messing with some ideas I have about capacitors and newman motors because...well...apparently, one thing everyone DOES agree on is that capacitors are dangerous. Which is kinda ticking me off - lol - and about being a sook, it's OK because I'm female...and probably old enough to be your mother...if not your grandmother...

[MarkE]

An AC induction motor uses electricity from the wall to establish the changing magnetic field that is ultimately responsible for the motor's operation.  In order to induce voltage across a winding, the winding has to intersect a changing density of magnetic flux where some non zero portion is orthogonal to the winding.  So if you just spin the rotor of an induction motor, the only voltage that you induce will be from residual field in the laminations and will be very small.

If you were to connect a battery or power supply across the winding that would establish a much stronger magnetic field.  If you would then spin the rotor, then you would induce voltage across the winding and the winding being connected in a closed circuit via the battery or power supply you would induce change in the current flowing through the winding.  Alternatively, you could establish the static magnetic field with a permanent magnet.  Then again, spinning the rotor would induce voltage across the winding.

[TinselKoala]

Wecome, cinco.

A computer fan motor is not an ac motor, though. Most of them are bipolar pulse motors involving a small amount of switching circuitry to pulse the four drive coils at the right time to keep the fan blade turning. There is a ring of "plastic" magnet material embedded in the fan blade hub, surrounding a stationary "stator" structure, usually 4 poles, and a tiny Hall effect sensor chip that switches input power to the coils in response to the sensed polarity of the ring magnet material. I just dissected one the other day and made a magnet polarity indicator out of the Hall chip and the blue LEDs that once made the fan look "cool".

I'm not sure if you can get current out of the system simply by, say, blowing air over the fan blades to get it turning, like you could with an AC synchronous motor system as MarkE describes. The coils will certainly generate a voltage but the chip won't be wired correctly for the thing to act as a generator. If you have microscope eyes and robot fingers, you might be able to rewire the coil connection, taking the chip out of the circuit, and then the thing will act as an AC generator when you force the blade/magnet to turn by blowing air thru the fan. The wire in the one I took apart appears to be #44 AWG, which is about as fine as a hair from my old grey head, if not finer.

The video to which you refer is a fake, of course.

Capacitors aren't dangerous in themselves... it's the charge you put on them that can be dangerous. Overcharging (over-voltage) an electrolytic capacitor can make it explode; storage of a lot of energy in the form of elevated voltages in a high-capacity capacitor can create a shock hazard; heavy capacitors will hurt if you drop them on your foot. There are safe ways of dealing with all these problems (wear decent shoes that protect your toes, for example, and keep high capacity capacitors shorted with a bit of wire when not in use, don't poke your fingers into active circuits, discharge big capacitors using a small-value resistor and a jumper lead before working on them, be darn careful about working on CRTs since the tube itself acts as a big HV capacitor, etc.)

[cinco]

Thanks guys!