E-mail and YouTube questions sent in about the Windmills video

Vega YouTube science mini film has over a million hits!

PLEASE NOTE: Many of the questions that have come in about the YouTube windmill video can be answered by looking at my web site at the following links:
power from nature and at: simple generators. Please also see the better quality science mini film videos on the Vega Trust site: Vega science mini films

Here are a few of the many of e-mails I have had about the YouTube video. To jump to the questions click on the question number below:
Question 1: information about making windmills
Question 2: I don't sell windmills
Question 3: specifications and plans
Question 4: windmills and light harvesting
Question 5: wiring into a house
Question 6: magnet generator
Question 7: charging batterys, AC and DC
Question 8: power and AC and DC converters
Question 9: turning windmills, vanes, slip-rings etc.
Question 10: other windmills
Question 11: which is best: HAWT, VAWT and the Flutter gen windmill?
Question 12: power and torque
Question 13: making 14 Watt
Question 14: flywheels

Question 1a
Hello, I have been wanting to make a wind turbine and found your video on YouTube. Can you give me more information on the 'generator' part and which of the 3 do you think I should build? Thanks, Ryan.

Question 1b
Hey Jonathan Hare we have seen your YouTube video and we have a big problem!! We have to build a windmill which produces energy and we don't know how to do this maybe you can tell us your way of producing but it has to be as cheap as possible love, your girls from Germany. Julia, Anna, Valentina and Isabel

Question 1c
I am Indonesian, who live in Bogor. I have fish hatchery which is the water to be aeration. I saw your presentation on YouTube and I think that I need wind blade to produce electricity. For that reason I need literature for building my own wind energy. Could you give me the web address of reference of detail system; wheel and wheel transfer for reduce or speedy the rotation. I prefer using horizontal blade. Thanks Dr Hare. Best Regards, Gane.

Question 1d
Hi Mr Hare whilst browsing the web on wind power as I want to build a wind powered battery charger to charge up the 12 volt battery for my hen shed to give them extended daylight in the dark months, I came across your awesome page on windmills and I really liked the all wooden windmill with right blades running a pulley system. Would it be possible for you to send me the plans on how to build one of these fine wind turbines please. Regards, Gary.

Answer (to all Q1). Dear Ryan, Thank you for the e-mail. Please go to my web site for more information on making windmills and generators,
see the links at the top of this page.

The most efficient windmill is probably the horizontal axis windmills but it depends on how much steady wind you have, how high you are above the ground, what you have available to you to make it, what you intend to power with it etc. Jonathan

Question 2
Dear Sir, I am Vadivel from India (Tamilnadu), I am a civil Engineer, just now I watched your home made wind mill in YouTube. It is very nice. Ok, can I get the wind mill for my home and that cost will be how much? please. help me, and reply me. Thanking you, Regards, Vadivel

Answer. Dear Vadivel, Thank you for the e-mail. I don't make them to sell I can only offer advice on making windmills not supplying them.
Please see my web site links (at the top of this page) for more details. Jonathan

Question 3
Hi JP, I saw you video on YouTube on windmill and I am amazed with your 2nd design of two rotating wings. If you can provide me the proportions or specific measurements of these wings I would like to implement it on terrace of my home. I was thinking of using multiple wings and a long straight shaft at the middle with slightly increasing angle from top to bottom to gain more strength. I appreciate your efforts a lot and have a great hope from you. Thanks and regards, Sachin.

Answer. Dear Sachin, Thank you for the e-mail. Please take a look at my web site (top of this page) for more details. Jonathan

Question 4
Hi Sir, How are you? I hope great. I was watching your program on YouTube about windmills for electricity. I want to know if you are doing it commercial. Cos I will like to buy already finished one for my family in Africa Nigeria. I am current living in Japan. Let me know now. I love your work. If you have idea about solar too let me know. Africa is suffering too much.They need help.

Answer. No, sorry don't sell windmills ready made. The windmills you saw are really for educational demonstration only, not really for making power in large amounts. Please take a look at my web site (links above and below) for details for solar projects and windmills: Jonathan
power from nature and solar furnace and water / pool heater

Question 5
I saw you cool video. Can you please tell me how you connect a wind turbine to the house to create electricity? There are many videos on how to build the wind mill, but no video on how to connect it to your house to generate electricity. Can you also tell me how to be able to post a comment on YouTube? I have never been able to post a comment and YouTube won't answer me. Lisa

Answer. Dear Lisa, I have the same problem posting on YouTube which is why I've made up this page! It only seems to work about 1 out of 5 times or less ... I am not sure what you are asking about connecting the wind turbine, do you mean how to fit a turbine to a generator and make electricity or how to use the electricity to make power for a house? The ones I show on the video are for educational purposes only, they don't make much power. They might charge a battery for an emergency torch or a small radio ... that sort of thing. If you want to make electricity to run a house then it's much, much, harder and you need to store the energy as the wind is not very stable / reliable. Jonathan

Question 6
Dear sir, how r u. I see your YouTube video on the web - this is beautiful. Sir help me . I want a home-made magnet power generator. I want a output only first raning . Can you tell me dimensions or send me drawing or any method for making. plz tell me. I see a YouTube result magnet generator clips. But I don't no design and assembling drawing. plz mail me. Thanks a lot. khuram

Answer. Dear khuram, please see my web pages as above (top of page). Jonathan

Question 7
First thing I want to do is thank you for your time. Next the question, when I finish the wind mill turbine that I am working on what do I need between the turbine and the battery to charge it with. Also what kind of battery is best to use. Once again thank you for your time and any info. would be helpful. Alton

Answer. Dear Alton, Thanks for the e-mail :-) 1) to charge a battery you need to make sure that the power from the windmill is DC not AC. So use a rectifier (diodes) to make it DC if its an AC generator you are using (like mine). 2) Then you need make sure that when the windmill is not moving the circuitry does not discharge your battery (the diodes should help). 3) You need to make sure that the power is i) not too high, otherwise it could damage the battery, but ii) also not too low so that it does not charge the battery at all. A regulator IC can do this (not expensive if you only want low power). A motor bike battery is ok or an old battery from an alarm or something like that will do. It all depends on how much you have to spend, and what's around if you are getting everything from scrap. please see my web pages at top of this page for windmill details. Jonathan

Question 8
Dear Dr. Jonathan, I saw video of wind mills created by you on Youtube website. It is very nice video. I live in India and interested in doing some work in non conventional energy systems. Initially, I want to develop one small wind turbine which will be able to run a bulb or two for around 2-3 hours. Being a mechanical engineer, I know little bit about the construction of a turbine. Also, in the video, it gives quite information about the same. But I do not know how to collect the electrical power generated. Can I use the power generated to charge an inverter batteries and use them whenever needed? Can you please guide me for developing this thing? I will be obliged if you can give me the guidelines about the electrical circuit used for the same. Hoping to get your kind help, Best Regards, Amrut (India).

Answer. Dear Amrut, Thank you for the e-mail. You have seen the video on the Vega site (and on YouTube) about the three windmills:
Vega science mini films

I have written up a lot of details in a paper on my web site so do take a look at this as many of the questions you may have may be answered (see links at top of page)

I made a 3 foot diameter windmill that could generate a few 10's to 100mW (depending on wind speed etc.) at about 5V so would be ok for charging a couple of AA bats or a mobile phone etc. You will need a diode between the two to stop the batteries discharging through the generator when it is not turning / producing power (the voltage doubler circuit in the article does this job). The main thing is to find a site that has a good steady wind as gusting winds are useless as the power averages out to very little (see the data / graphs on the article, links above). I used plastic sheet ca. 2mm thick for the blades and it seemed to be ok. Once moving the weight is taken off the blades but gusting can cause problems with blades braking and flying out / off. I used a simple generator so that everything was homemade but a commercial gen or a dc motor would be better if you want max power.

Wind is not often reliable and so the best thing is to use the windmill to charge up a battery (or set of batteries) so that you can store the energy. To do this you will need a regulating device to stop the windmill voltage going to high on fast wind speeds and also to stop the battery being discharged when there is little wind. An inverter can convert the DC battery (say 12V) power into AC mains electricity (eg. 110V or 240 V). All this is possible but not easy in most locations and not very cheap. To be honest it's not very easy to make everything yourself and still make something that can run a house, but you can make a device that can charge up an emergency torch or run a radio etc. Jonathan

Question 9
I'm surprised as a DR. you would not know that all you need to keep the windmill facing into the wind is a simple VANE. A weather vane is a horizontal tail that keeps pointed into the wind. (This is not rocket? science). (Sorry, I didn't mean to be so harsh. Thanks for the posting)

Answer. Ha! Yes, you are quite right. I should have said the windmill needs to follow the wind (automatically using a tail or vane) rather than suggest that someone has to move it by hand! The trouble with windmills that use a tail is that that the whole thing turns around so you need some kind of slip-ring for the cables so they don't get tangled-up / snagged. So we didn't mention this as we wanted the movies to be very brief and to the point. Jonathan

Question 10
I enjoyed your video on homemade windmills very much. I am an amateur trying to build my own. Do you think this bicycle idea is possible/practical on a large or even semi-large scale for, say, the roof of a single family home? I would use plexiglass for the blades rather than clear packing tape as it might not harden and crack as fast. I hope this email makes it across the Big Pond:) Thank You, Jean, Dalton, Georgia

bike wheel windmill

Answer: Jean, Thank you for the e-mail. I just watched the YouTube bike wheel clip - its a nice video. The thing is that the ball bearings at the center of the wheel provide very little friction and so the bike wheels turns with very little wind. But as soon as you attach the device to a generator I expect it will stall it. The more power you try and create from a generator attached to a windmill the more 'force' you need to turn the gen. I have a feeling that this windmill - nice as it is for a garden 'thing' - won't have a great deal of torque require to drive a gen. You could get it to make enough electricity to drive an LED, but not enough I expect to charge a phone or walkman. Jonathan

Question 11
I saw your video on windmill where you show, traditional windmill, HAWT (horizontal axis wind turbine), VAWT (vertical axis wind turbine) and the Flutter gen windmill. Which one produces more energy the flutter or VAWT?

Answer: The Flutter gen windmill is a form of VAWT but at the moment you can see that its juts a very basic prototype that shows the first principles but does not (yet) produce much in the way of power. It seems that the 'classic' HAWT are generally more efficient, the Savonious VAWT are next and then finally the Flutter gen windmill. Because they tend to need a surporting structure (to keep them vertical) the Savonius types tend to be placed on the ground but this is not where the best wind is. The HAWT tend to be mounted high enough to get the clear, reliable wind so they often work better. Jonathan

Question 12
What is the relationship between torque required to draw current from the AC generator? Do I need more torque as I draw more current? Thank you very much,

Answer: You will find that if you don't draw any current from the gen coils the magnets turn very easily but as power starts to be generated and current flows to a load the magnets will be harder to turn. In the extreme case of a short circuit you will need quite a lot of torque to turn the magnets. The exact amount will depend on the losses (resistance etc.) in the coils, the efficiency and size of the generator and the gearing of course you have between the windmill and generator. Jonathan

Question 13
Hello sir, my name is Sagar and I am an Engineering student in India. we have selected a project of building a wind turbine with the help of a bicycle wheel to produce a power of 14 W which would light a CFL .So I wanted to know that is the project feasible to implement. if, yes what are the parameters that I have to concentrate(according to my calculations I need a 0.75m diameter wheel) is it right. if no.. how can I make the project feasible. I would expect your guidance in my project sir

Answer: Dear Sagar, Thank you for the e-mail. Please take a look at my web site for more technical details (links above). My windmills are really to show the basics and are not state-of-the-art efficient designs. However if you have the space and resources they can all be scaled-up to produce more power and 14W should be easy enough as long as you have the wind of course. This is not a joke, many people think they have 'lots' of wind only to find when the actually put up a wind turbine that the average power (say over 24 hours) turns out to be quite small. This is because a place with high speed gusting wind is not nearly as good as a place with constant light wind. Really to be a proper project you need to investigate the best place for the most reliable wind in your area - that will eventually provide the success you need.
If you are going to make a generator, an old 12V power tool (with the electronic circuits removed) works well in 'reverse' as a generator .. I have got 12V at 1 amp from such a device, so the power = 12 x 1 = 12 Watts so with a bit of experimentation 14 Watt should be practical. I can't say what particular size wheel will 'do the trick' as it rather depends on windspeed, height of elevation of the turbine, friction and the efficency of the generator etc. Yours Jonathan

Question 14
Hi Dr Hare, i am a 2nd year mechanical engineering student. I just watched your video about windmills on youtube and i have a question to ask you about them. Can I use a flywheel to 'stabilise' the production of power? Or can I use a flywheel for time when the magnitude of the wind decreases so as to get a relatively constant value of power? did you get my point? Thank you so much, Josh

Answer: Dear Josh, Thanks for the e-mail. Yes, I think you can. On the first windmill I think you can see that there is quite a large pulley on the back which drives the generator. This does help to average out the rotation of the windmill. Strangely, although the large vanes should provide more power than smaller blades, I found the smaller blades went around faster (they are lighter). As the generator responds to velocity (angular velocity) the small blades gave more power! The large vanes had more torque / "umph" but I didn't need a great deal of torque to drive my little generator so smaller blades won-out (see the article on the 8-blade windmill for more info, see links below). So I guess you don't want too much flywheel weight in case it slows the windmill down. If you have a place with great wind then I think a flywheel would help but if it's quite unreliable wind speed and relatively slow it might have a tendency to stall the windmill. Jonathan


Dr Jonathan Hare, Physics Dept., The University of Sussex
Brighton, East Sussex. BN1 9QJ.

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