Have stacks of old computer equipment gathering dust ? Now you can put some
of it to use! This guide shows you how to use PC fans as mini
wind generators for recharging solar lights and ni-cads. You'll need
some basic soldering skills, but this is otherwise a very easy project.
My little wind generator makes around 1.5 - 2V in a 8mph wind, about
20ma into a ni-cad. This wasn't a huge success, I'd hoped to get a
little more power out of it.
Have a look at some new photo's at the bottom of this page:
Materials needed:
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Thick plastic bottle.
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Old PC fan, bigger the better!
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A few feet
of small wire
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A piece of wood about 1.5" square and around 20cm
long
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Two lengths of steel tubing that slide inside of each other,
about 1/2"
- 4 Schottkey
diodes, I used BAT85 but any will do
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Epoxy
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Super Glue.
- Zip ties
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An old CD
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Finished Windmill
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Step 1: Dismantle the fan
Normally these fans are held together by a little circlip. This is
hidden under a seal on the back of the fan. Remove the sticker, and
prise the little rubber seal off. This should reveal the circlip, you
can prise this off with a little screw driver. You should be able to
pull the blades off now.
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Dismantled Fan
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Step 2: Solder on the wires
Look at the copper coils on the fan, there should be two or three wire
legs, these are the connections to the coils. One of them will have two
pieces of copper wire connected whilst two have only one piece of copper
wire connected. You want to solder two wires to the legs with only one
copper wire.There should be just enough metal showing to solder onto.
Prepare two lengths of insulated wire by tinning the ends. Solder these
onto the coil legs.
With the wires soldered, you can remove any
electronic components from the board. I just snipped the legs with some
mini wire cutters.
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Three wires soldered onto the legs
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Step 3: Building the rectifier
The rectifier turns the AC output into useful DC power. You need 4
diodes for this. Snip the legs on two of the to about 1cm on the side
with the black line, and three to about 1cm on the side without the
black line. Bend the long pieces over to connected them all together
(see photos). Solder them all together, then solder the three wires to
where the two diodes are connected together. When you've finished the
rectifier together, you can add the output wires. I used about a meter
of bell wire, you can adjust this to suit your needs.
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Finished rectifier
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Step 4: Test the alternator
You can test to see if the alternator is working now, fit the blades
back into the fan and connect an LED or multimeter to the output. Give
it a good spin and see if it works!
After you've tested it (and it's working!) you can remove the outer plastic case and the blades of the fan. You can
just snap the blades off, I cut the supporting parts of the box casing
with wire cutters. |
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Step 5:
The blades are cut from a thick plastic bottle - normal plastic drinks
bottles won't work here, it needs to be thick plastic like that found in
bleach bottles. Cut the top and bottom off the bottle, this. I made a
template on paper and traced this onto the plastic. Make sure that the
blades are all the same. There was no particularly scientific design to
the blades, I just made them as long as the plastic would allow, and a
rough "blade" shape!
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Finished blades
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Step 6:
The three blades are glued to the plastic hub of the alternator. If your
wondering about the angle of the blades, I found that the natural curve
from the plastic bottle works fine, it doesn't need any angle adding.
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Gluing the blades in place
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Step 7: Make the tail and alternator mount
The motor is glued to a piece of wood which pivots on the steel pipes.
The tail is made from an old CD.
Drill a hole the same size as
the steel tube all the way through, if it's a loose fit, you can epoxy
it in place.
Then I cut a slot in the other end for the tail,
this should fit the CD. With the CD in place, I drilled two holes
through the wood and through the CD, these are for the screws. Make sure
you drill through the CD as so it doesn't shatter when you screw the
screws in.
Now you can mix up some epoxy to glue the alternator
to the end of the wood. When it's glued in place you can zip tie the
wires securely, and thread the output wires through the tube. I zip tied
the rectifier to the underside of the windmill, and sealed around the
connections with some epoxy, which should keep it corrosion free.
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Alternator glued on
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Step 8:
Here's what I use for my tower, it's a garden "corkscrew" type
thingy-ma-jig. I don't really know what it's called. It's great for
supporting small towers for mini wind gens, only £4 from lidl too.
The actual tower is a piece of thin wall tubing with the larger tube
zip tied to the top, for the bearing point of the wind mill.
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Easy to build tower
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Here's some photo's of how I converted a different fan :
In this fan, the PCB wasn't glued down, it was secured with plastic clips. I was hoping to be able slide
the PCB out and solder new wires to the underside, but I was a little heavy handed, and there wasn't
really enough loose wire.
So the wires got ripped off the fan:
I unwound a bit of the wire to give a bit more space to solder :
Two of the coil wires are connected together, I just followed the original wiring from the PCB.
Then the two output wires are soldered onto the other coil wires
I glued the wires down:
More guides like this :
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