small windmill to generate 24vdc 3

[bob1371]

Hello,
My son and I are working on a school project. He is building a small windmill that will power lights in a little log cabin that he has built. He will use a small fan to make the windmill turn and Im looking for a small motor/generator that will give 12 to 24 volts at slow speeds. The windmill with be 16" tall so it doesnt have to be something really small. Any idea's will be greatly appreciated. I have tried Radio Shack and a couple of small hobby shops but no luck.

thanks,
Bob

 

[SteveKW]

Maybe a cheap 12vdc (permanent magnet) portable car fan type motor?
That may have to turn pretty fast though!

Does it have to be 12 volts? Can you use a lower voltage bulb?

A smaller and lower voltage bulb could be run from a simple DC motor from Radio Shack!

Pulleys could be used to increase the motors speed and voltage output too.

 

[bob1371]

thanks for the reply. We could use smaller bulbs. I have tried a few motors out of broken down RC cars but only getting about 3 volts from them. I saw a few cheap motors like you mentioned at Radio Shack so I may go that route. The reason I was looking at 12/24 volts is this will all eventually be run by a micrologix 1000. It is a really detailed setup that he has worked on for quite some time. Gonna use the plc to control some automatic gates and a couple doors.

 

[unclesyd]

Here is one 24V motor from Edmund Scientific.

http://scientificsonline.com/product.asp?pn=3081069

Check out the boating supply people as nearly all thier motors are 12V. Also some commercial boats use 24V or 32V.

 

[Digitalwoodshop]

How about a bicycle light generator that runs off of a bike wheel?

 

[ScottyUK]

I think you're going to be stuck with permanent magnet motors which will give a speed-dependent output voltage. You will definitely need to use belts or gears to increase motor shaft speed to order to get any appreciable voltage out of a motor driven as a generator.

An automotive fan motor might be a possibility - the dashboard blower motors are usually a rated at a few hundred watts, and a motor from a scrap dealer would be very cheap to try.

Approaching the problem from a slightly different angle, if you light the cabin with LED's rather than filament lamps, the voltage and current demand will be very small, so your motor doesn't have to spin as fast. If you want to really show off you could use a small regulator IC - a 78L05 maybe - to keep the LED intensity constant as the 'wind' speed changes.








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Start each new day with a smile.

Get it over with.

 

[jbartos]

Suggestion: Visit

http://www.panasia.org.sg/nepalnet/crt/windmill.htm

for small 24VDC electric windmill examples

 

[OperaHouse]

It seems easy, but this is a daunting engineering task. Harbor Freight has a little ornamental multi blade windmill that can barely overcome friction. Small motors are designed for high speed with the voltage applied proportional to speed. So, for a low speed application you would prefer a 180V motor. Lighting this little cabin would blow every other project off the table. While others see this as a technical problem to solve, I have another view.

Form vs. Substance......... This is like a big budget movie that flops at the box office because it doesn't have a good story line. I can say this because I volunteer as a judge at science fairs. Use the windmill and cabin as a backdrop. A project doesn't have to work to be great. I am more interested in the initial tests that were done that only generated a couple volts. Run those again and plot the voltage vs current by changing the load resistance. Find where the maximum power was generated and what happened to the speed. Power developed will be about the same no matter what motor is used. What effect will diameter have, what rpm do you get, and what will be the blade speed at the tip. You can take two identical motors and drive one as a generator from the other. Calculate the power going into the motor and that developed by the generator to estimate generator efficiency. Assume both efficiencies are equal. How could you measure the real efficiency? If you had a large supply of these generators that only generated a couple volts, could you charge smaller batteries and use them to fun your lamp for 2 hours. What are average ind conditions in your area? Lighting a lamp may look impressive but we are more interested in the thought process and how the student has researched the material. This isn't about lighting a lamp but the challenges in wind generation. From my judging handbook:

"Other projects will seem too sophisticated to be the work of a student of the age you are interviewing. That hunch merits further questioning, but not a conclusion. Some students are extremely bright. Others have helpful parents who will spend hours ensuring that their children have all the resources and contacts they need. You must distinguish between the students who used resources with comprehension and the student who just used them. Although child prodigies do exist, it is unlikely that ten of them will be placed side-by-side in the section you are judging. Your task is to make sure the real scholars are recognized. When you come to a project that obviously is the work of the student and yet original, simple, well conceived, clearly displayed and well understood, you have a winner!"