Storing Cookies (See : http://ec.europa.eu/ipg/basics/legal/cookies/index_en.htm ) help us to bring you our services at overunity.com . If you use this website and our services you declare yourself okay with using cookies .More Infos here:
https://overunity.com/5553/privacy-policy/
If you do not agree with storing cookies, please LEAVE this website now. From the 25th of May 2018, every existing user has to accept the GDPR agreement at first login. If a user is unwilling to accept the GDPR, he should email us and request to erase his account. Many thanks for your understanding

User Menu

Custom Search

Author Topic: PC Fan Generator  (Read 51722 times)

geotron

  • Full Member
  • ***
  • Posts: 118
PC Fan Generator
« on: March 21, 2010, 05:26:43 AM »
I've been experimenting with 3x6mm disc magnets lately,
and have found that connected along their diameters and
fixed to a PC fan, it makes quite an effective spinning
device.

http://www.youtube.com/watch?v=ASVbgBCq57s

The motor powering the fan is a 12VDC .18mA running at 5V.
All of the magnets - 12 of them in groups of two are high-
powered Neodymium permanent magnets, and weigh in at probably
3-5x that of the fan by itself.

The ratio of total magnet power between the motor itself and
the ones I have attached is far in excess towards the latter.

I'm thinking of the weight & flux-strength of the magnets in
the motor versus that of the Neodymium spinners. The ratio is
so far in excess I will not even attempt a guess.

What I'm thinking to accomplish with this small project is
somehow winding a bunch of copper wire into a shape or shapes
that will be able to pick up a charge from the spinning
North-South-North-South top surface of the device.

Honestly I do not know what other parts (diodes etc) that I
may be in need of to get it working properly, but the concept
of overunity I'm getting at is to spin a proportionately huge
amount of magnets around pickup coils with a tiny DC motor,
thereby amplifying the output.

The power input is 5V 74mA... and so far, my attempts at
using a single small coil for collection of charge have been
unsuccessful. What I did was hook the ends of a small 6mm
wide coil directly to the leads on my meter.

My working knowledge of electronics is not exceptional by any
means, so for now I must rely on the probablility that I'm
going about some stuff completely wrong.

Any and all help will be greatly appreciated!


e2matrix

  • Hero Member
  • *****
  • Posts: 1956
Re: PC Fan Generator
« Reply #1 on: March 21, 2010, 06:54:58 PM »
Almost surprising the magnets stay in place.  I think you want to turn your coil 90° from the way you have it - i.e. the bottom of the coil (or top) should face the magnets instead of the side of the coil. 

mscoffman

  • Hero Member
  • *****
  • Posts: 1377
Re: PC Fan Generator
« Reply #2 on: March 21, 2010, 07:24:57 PM »
All you can do is put bunches of coils around the motor's periphery.
You can use diodes preferably either germanium or Schotky
that have lower .2vdc pedestal voltages to put all the coils
in parallel boosting their current. Or you can run each diode
to a capacitor and stack up those boosting it's voltage or a little
of both.

Here's the rub, as you add coils and as you begin to put a load
resistor on them to extract electricity - you make the rotor
to harder to turn, ie you add a braking force to the rotor's
turning - As the motor becomes harder to turn that little
circuit inside the motor makes use of more input current or
else the motor slows down. The energy you use will almost
always be exactly balanced with what you get.
This is why generators are so extensively used...they can do
this balancing act with almost 100% efficiency. To see this
happening spread a few of the magnets around outside the
loaded rotor. The rotor should begin to cogging and the motor
using more energy. Exactly the same thing will happen with a
electrically loaded coil.

:S:MarkSCoffman

geotron

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #3 on: March 21, 2010, 09:53:25 PM »
Ah... interesting.

Now what if one was to collect the back-EMF from
the motor, as well as the same from each coil,
and then rout all of it into the same location
as where the foward-current of the coils lead to?

Alternately, is there a way to collect back-EMF
from the motor and simply feed it back into the load,
thereby helping to speed up the fan?

FatBird

  • Hero Member
  • *****
  • Posts: 1178
Re: PC Fan Generator
« Reply #4 on: March 21, 2010, 11:06:32 PM »
The inside magnets aren't doing anything because they are too far from the coil.

1.  All you need to do is to remove all of the magnets except the outermost 2 at both ends so it is balanced.

2.  AIM the CENTER of your coil (NOT the side of the coil) ABOVE the 2 rotating magnets.  The closer you hold the END of the coil to the magnets, the more voltage it will output.

3.  The output will be AC which is fine.  You should get enough output to light up a small flashlight bulb, or at least several LEDs in parallel.

.

geotron

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #5 on: March 22, 2010, 12:39:25 AM »
This is where I'm thinking of going with it...

Having three coils to start out with so each
one collects a different polarity with the
N-S-N-S of the tops of the magnets.

mscoffman - I tested what you described, holding
some magnets close to the spinners to slow them
down and draw additional energy.

What I found was that the voltage stayed precicely
the same, while the current draw bumped up maybe
around 5mA - I was really slowing it down too.

The next step for me is to find some diodes to
work with, and a potentiometer to find the just
the right speed where the magnets are spinning
as fast a possible without flying away.

mscoffman

  • Hero Member
  • *****
  • Posts: 1377
Re: PC Fan Generator
« Reply #6 on: March 22, 2010, 02:14:08 AM »
Move some of the magnets on the inside to additional outside positions
maybe like a square, hexagon, octagon. Actually you should alter the N/S
poles of each of these on the outside so the coil doesn't see one big
'N' or 'S' all the time. These additional "poles" will make your AC go
up in frequency per motor revolution.

Leds have a pedestal voltage before they turn on, so they
are not quite as good as pure loads as resistors are.

Ok, the motor control circuit can either increase current which
may be difficult for it if the voltage input is 5Vdc low. (your PS
supply should be regulated at 5Vdc). Or it has to let the motor slow
down. The generator function is proportional to RPM,s so it would
automatically cut the voltage, power and braking back as the rpm
drops. Allowing it to seek a steady state.

:S:MarkSCoffman

geotron

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #7 on: March 22, 2010, 03:23:02 AM »
Hmm - in order to add additional magnets I would
have to retool it a bit to accomodate a large flat
disc to glue them on to. If I can get some preliminary
results tomorrow when I hopefully find some diodes,
then I'll have a go at it.

What I ought to figure out at this point is how to
change the resulting current output of the coils from
AC into DC.

I'm fairly certain there's a quick way to go about it,
but a bit of searching has left me without an answer.

Edit:  Alright, I get it now - the diode IS what turns the
AC into DC by blocking half the waveform...
« Last Edit: March 22, 2010, 07:14:51 AM by geotron »

geotron

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #8 on: March 22, 2010, 03:34:29 AM »
...
« Last Edit: March 22, 2010, 07:14:16 AM by geotron »

jadaro2600

  • Hero Member
  • *****
  • Posts: 1257
Re: PC Fan Generator
« Reply #9 on: March 22, 2010, 04:36:38 AM »
Alright, I get it now - the diode IS what turns the
AC into DC by blocking half the waveform...

Actually, if you take the fan apart, you've probubly got a circuit board on there which converts the DC to AC or pulses the coils on the fan board so that they alternate polarity.

The fan assembly usually consists of a cheap plastic shell, inside of which there is a soft ceramic magnet ( ring shaped ) which has two north and two south poles n-s-n-s around the rim, or north on one side and south on the other if there are three coils on the fan board.

It's not really practical to have brushes on these types of fan because they're intended to be run for long periods of time, so they use a controller board to create induction ....

geotron

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #10 on: March 22, 2010, 07:22:36 AM »
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

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #11 on: March 22, 2010, 07:25:07 AM »
...

geotron

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #12 on: March 23, 2010, 12:48:58 AM »
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

  • Hero Member
  • *****
  • Posts: 1377
Re: PC Fan Generator
« Reply #13 on: March 23, 2010, 12:51:32 AM »

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

  • Full Member
  • ***
  • Posts: 118
Re: PC Fan Generator
« Reply #14 on: March 23, 2010, 02:47:13 AM »
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?