PC Fan Generator

[geotron]

The fan blade housing had a flexible circle-shape
magnet that I removed with its metal ring form.

It was surrounding the outside of the inner assembly,
identical to the one I am now using to spin the discs -

[geotron]

...

[geotron]

I've obtained some diodes and assembled a small
test coil with one of them, and so far no results.

The diode is a Radioshack IN4005 with the following
specifications -

Foward Voltage Drop: 1.6V
Max. Surge Current:  30A
Foward Current: 1A
Reverse Current: 10uA

I've checked for resistance with my meter on the
assembled coil-diode circuit and its ok, so my guess
is the diode is of the wrong type.

My meter was set to the 10V range, and recorded no
movement at all no matter how close I held the coil.

[mscoffman]

That little rectangular black component is the motor control circuit
It's relatively complex inside and probably contains a Hall effect
magnetic sensor that can "see" the rotor magnetically so that
it can sense how fast to send pulses to the coils. A fan needs
to turn one specific direction and the coils are set up in an
asymmetric fashion to create that directional spin. The three
leaded Q1 is a final transistor that the control-circuit pulses
so that it itself does not overheat.

:S:MarkCoffman

[geotron]

Well, I'm certain now that I've obtained the wrong
class of diodes - looks like I'll have to order them. 

As described in rukiddingme's thread on Schottky diodes,
it looks as if I'll have to go with either the rk44 or
bat46... or something equivalent.

Does anyone have a guess on what kind of voltage I can
expect to gather from the red coil in the pic? With the
1.6V diode on there, nothing registers so I'm thinking
that if anything is being collected at all it would be
less than this value.

With my meter set on 50VAC connected to a coil without
a diode there is nothing registering either, so in this
case it may be my meter isn't sensitive enough on the 50V?