Hiya. I need some advice. I've been poking around the web and the forum here, and can't quite find what I'm looking for...
I want to create a mini wind turbine using a mini motor (it needs to be micro size so I am planning a 1.3 volt motor presently)
I want to power a few LEDs (pref. RGB), and perhaps program a mini arduino so they will blink in various patterns.
Is this possible? Recommendations would be wonderful. Point me in the right direction please.
yes, no problem at all, but consider charging a battery from the turbine and feed the Arduino from that.
blinking LEDs sketches are easy to google for, there even exist sketches that do not use the delay statement I am told 
robtillaart:
there even exist sketches that do not use the delay statement I am told
Far too complicated though Rob.... Delay Rules, Alas.
(it needs to be micro size so I am planning a 1.3 volt motor presently)
Consider using a higher voltage motor, like 6V for instance. It will be very very difficult to power any system with 1.3V.
Thanks so much all.
Anyone know what minimum size rechargeable battery would be suitable?
I was thinking the same think about the size of the motor. I want to try to get away with as small as possible.
What do you mean by micro size?
And what wind speeds are you planning for?
The power output of a wind turbine is proportional to the cube of the windspeed and to the square of the rotor diameter. And small turbines are less efficient than large ones so i would go for at least 0,5m rotor diameter in order to get a few Watts even at low windspeeds. I also would go for an dynamo/alternator followed by a voltage doubling rectifier and a switching regulator in order to get a stable working voltage.
nilton61:
What do you mean by micro size?
And what wind speeds are you planning for?
The experiment calls for small size constraints. A motor would need to be no more than 2-2.5 cm in diameter.
Wind speed would generate around 10-15 psi.
This would need some more explaining.
What i was asking for was the rotor diameter since it is dimensioning the output power.
And windspeed giving a pressure rise of 0,7 atmospheres? Are you using some kind of venturi tube?
nilton61:
This would need some more explaining.
What i was asking for was the rotor diameter since it is dimensioning the output power.
And windspeed giving a pressure rise of 0,7 atmospheres? Are you using some kind of venturi tube?
Sorry, for not being able to clarify. I am seriously in the beginning steps of researching if this would be possible. I am researching motor possibilities and don't have an answer yet. But yes, precisely! the turbine would be placed in a venturi tube of sorts. I would like the rotor to be 2cm if it was possible.
Really can't see a motor that small producing enough mAs to power a few RGB LEDs, even one with more than one color on at a time would be a challenge. If the motor needs 1.3V whats the mA draw? You won't get that out of it as a turbine.
What will power the Arduino?
Diode, super cap, joule thief and a white LED maybe?
I just came up with an idea.
A 50mm cpu fan has magnet housing diameter of 21mm (excluding the blades). Inside there is a 2 (or 3, dunno) phase winding wich could be used as an alternator. I will do some experiments to see if this is feasible. (I ruined the wiring in my first attempt so i will have to go looking for more fans...)
Maybe you could use the exsisting blades as well perhaps just add some lead shovels or similar.
Adam3B:
I would like the rotor to be 2cm if it was possible.
Use a computer fan?
Unless you are blowing the air from a compressor of some sort a 2cm rotor won't generate any useful amount of energy.
If you are using a compressor STOP. Just use the electricity that would otherwise power the compressor.
...R
Edit to add ... written in parallel with @nilton61
I think computer fans are electronically commutated.
Is it possible to use them as a generator ?
Thats exactly my idea. Being electronically commutated means that they actually synchronous machines (from a structural point of view, having rotational magnets and stationary coils). So you get rid of the electronics and replace them with a multiphase rectifier with shottky diodes. That should give you a decent efficiency
Not sure where the op is from but here in the uk whe have led speed warning lights which only come on when the speed is exceeded.
Typically they are powered by both a solar cell and a wind fan.
Fan is approx 80 cm dia at a guess.
May give some idea of the available power, in the uk its generally low with few sites being suitable for power generation.
They need a certain windspeed to become operational.
Hi, a 2cm rotor is not going to work.
You still have to mount the generator/alternator behind that and ensure that the air flows cleanly over it, once the air has moved through your blades you cannot forget it, you must allow it to get away.
Thats why you cannot have a 100% efficient wind turbine, if you did, the air would be stationary behind the blades after giving up all it energy (Velocity).
Tom.... 
A little update for the fun of it.
I disassembled a 50mm cpu fan. Just removed the back sticker and carefully pushed out the bearing. Then i removed all components except the hall sensor and moved the three connecting leads to the three solder pads for the coils.
Connecting the leads to oscilloscope revealed the following:
More to come...