Wind Turbine Science Fair Project - Generator Coil Problem

[MikeShelton]

Homework Statement

My son and I have built a wind turbine following the plans on: Build your own Wind Turbine Designed by Dave Mussell http://www.re-energy.ca/docs/wind-turbine-cp.pdf" .
These plans were inspired by the Picoturbine: link to manufacturer and link to PDF.

We used 30 AWG gauge wire at first, but didn't get enough voltage to light the Light Emitting Diode (LED). So, we re-wound the coils with 300 turns of 27 AWG wire and we still don't have enough voltage to light the LED.

The turbine spins nicely, and the voltmeter reads around 47 when set to DCV 2000m.

We want to know why the LED is not lighting up.

Any suggestions would be welcome!

I'll post pictures in follow up posts.

Thanks,
Mike and son

Homework Equations

I don't have an equation that gives the 1.5 volts out of 4 coils of 300 turns of 27 AWG wire. The closest equation I can find is:

Wheeler's Formula (single layer air core coils)
L(uH) = (r^2) * (N^2) / (9*r + 10*h)
where:
r = coil radius (inches)
N = number of turns
h = coil height (or length) in inches

But this doesn't yield volts, and it doesn't tell me how long the 27 AWG coils should be.

The Attempt at a Solution

Right now, we are using 4 coils of 300 turns of 27 AWG and getting about 0.047 volts, which isn't nearly enough to power the LED.

We want to know why the LED is not lighting up.

Any suggestions would be welcome!

I'll post pictures in follow up posts.

Thanks,
Mike and son

 

[MikeShelton]

Here is the turbine:

We used CDs instead of cardboard for the stator and rotor.

 

[MikeShelton]

Here are the coils, the small ones were 190 turns of 30 gauge (AWG) magnet wire:

The large one is 300 turns of 27 gauge. This is what I have now.

 

[MikeShelton]

Here is a shot showing the gap between the coil and the magnet. Looks like it is about 1 millimeter, like the directions recommend.

 

[MikeShelton]

Here is a voltmeter reading.
I'm not an expert at reading these, but I think this means -0.047 volts DC.

The readings jump around a lot while you spin the turbine, but this is a typical reading.

I've bought an analog meter, but I haven't tried it yet.

 

[MikeShelton]

The analog meter also gives very low or zero readings.

 

[RTW69]

My electronics is a little fuzzy but I believe you voltmeter is reading 47 millivolts. Reverse your probes and the voltage should read positive. The dial is turned to 2000 millivolt range meaning it will read UP TO 2000 millivolts or 2 volts max.

 

[MikeShelton]

RTW69,

Thanks for the advice. That makes sense. That is a better explanation than I found in the mulimeter's instructions.

We are considering scrapping the coil and magnet part of this project and setting up a pulley to a little Radio Shack DC motor. I'll post pictures when we finish it.

Thanks,
Mike and Son

 

[RTW69]

It looks like LED's need about 2 volts to operate.

 

[MikeShelton]

Yes, the radio shack red LEDs we are using require about 1.5 v to light. This is easy with the toy motor, but we can't get anywhere near that with the magnets and wire. It looks like the Radio Shack magnets are much too weak for this use.

Thanks,
Mike and Son

 

[alkis]

first the magnets are to far apart
the meter on the 200 no 2000
and turn the wires of the meter ,that way you don't have _

 

[MikeShelton]

We ended up changing the hand wound coils for toy motors from Radio Shack. It turned out OK. Here is the resulting project

Good luck to anyone doing their science fair project. My advice: try science buddies website for a more simple project instead of trying to make your own vertical wind turbine from parts at Home Depot.

Good luck,
Mike and son

 

[dinablaster]

1. multimeter is on dc and should be on ac. if is not link after LED.
2. you magnets are to far and are ceramic 5 time weaker than neodymium.
3. your result is nicer and better than what you try to build.

 

[NascentOxygen]

1. multimeter is on dc and should be on ac. if is not link after LED.

I think dinablaster makes a good point.

The generator is really an alternator, so using the meter on its DC range gives a meaningless reading. Switching it to AC probably won't improve things, the frequency is probably too low for the innards of an ordinary AC meter.