The forums are retiring and are now closed for new topics and comments. The existing content will remain online and accessible through 2020 to provide everyone the opportunity to save any relevant information. In the spring of 2021, these Community forums will be taken offline.

Search for wood bridge in Topics


Model bridge

Hello,             What is the best way to construct a model bridge out of small wooden icecream sticks  The requirements are as follows: 1) the icecream stick dimensions are 2mm deep 10mm wide by 115mm long 2) the bridge has to be 1 metre long and about 20-30cm wide 3) the only materials are the wooden icecream sticks , wood glue and cardboard to form the deck of the bridge. The idea is to construct the bridge so as to be able to hold the most weight.The most weight achieved so far is 450 kg before breaking

Topic by jamesk891    |  last reply


making a bridge on a sledge ?

I know thats a wierd title but i have an explanation. i reckon its going to snow soon and to get to the best hill me and my freinds have to cross a frozen stream about a foot wide but 6 foot at the top of the v shape its in  we cant jump like we would any other time of year because of the sledges weight we couldnt get far enough and we`d land on the stream and get very cold. so is there any way that anyone can suggest of atatching a bridge to my sledge (a bit like the mt 72 tank principle). four main criteria are:lightweight ,removable,cheap and 3 foot long(the sledge is already three of the six foot) i have an idea but its heavy.the sledge is wooden and has an 8inch by 3 foot space underneath and is about a foot off the ground.all ideas are welcome! please help.thanks ,wood wizard. UPDATE i have limited wood can anyone suggest a design where the bit of the sledge where you sit becomes part of the walkway. also im getting two of the desgns ive thought of on my site : http://my-site-me.webs.com/

Question by wood wizard    |  last reply


whats a good design for a mini balsa wood bridge? it has to hold 100 pounds!?

Must have: mass- 45.0 grams or less length- must be longer than 38.0 centimeters (2.0 cm by 2.0 cm square rod must be able to pass through full length of roadway surface) height & depth- can't extend more than 12.0 cm above test support surface and 10.0 cm below it. roadway- will support 100lbs load, cannot be more than 2.0 cm above test support surface BRIDGES CAN'T BE WEDGED INTO SUPPORTS) someone please help, i'm stuck!

Question by erikabixby    |  last reply


How to make a strong bridge by using

How to make a strong bridge by using 15 straws , 35 paddle pop sticks , 3 sheets of cardboard, 50cm of sticky tape, wood glue? my bridge have to be 25cm long and 14cm wide. Thank you for helping

Question by bryan1234567890    |  last reply


What methods allow wood glue to seep into basswood better?

Hi Everyone! I am currently working on a Basswood bridge project and my initial testing came to conclude that failure of my bridge was due to break joints! i took a look at the joints and the glue and these locations had barely seeped into the wood enough that it eventually broke off from weakness! I am aiming for my bridge to break within the sections and NOT at the joints. Are there metods like baking? soaking? the wood and glue so that the glue can seep in better? Specifics too please! I have seen people soak it, or "damp" i should say. But I have no clue how much to damp it or any of that! Acetone came up too.... not to sure though, how does this even work?! -Thanks noobie

Question by noobiefied    |  last reply



Sitar bridge mod (for floating-tailpiece guitars) idea

The characteristic sound of a sitar is created by a bridge that gently rolls away from the strings; this creates a buzzing timbre which quickly depletes higher overtones in the string's vibration (I could draw some diagrams if anyone's interested). This type of bridge is something I'd like to make as a removable modification for a guitar. My guitar has a "floating tailpiece" as I believe it's called, in which the strings pass beyond the bridge to the tailpiece. The segment of the strings below the bridge have no part in tone generation, and so could have an object attached to them (a piece of wood wedged between the strings, perhaps) without affecting the guitar's tone. If some object (the "clamp") were attached to the strings immediately below the bridge, another object (the "sitar bridge") could be affixed to it some minuscule distance from the vibrating portion of the strings. The sitar bridge would not make contact with the strings at rest, and so would not be a node of vibration (and not affect the strings' pitch), but when the strings are played, their vibrations would make them rattle against the sitar bridge - much like the bridge of an actual sitar. So how about it? I think it'd be an interesting and relatively simple mod that could be made to be removable and not destructive at all to the actual guitar. I unfortunately have no idea how to refine the concept any further than what's written, so I leave it up to any willing DIY-ers. It all makes sense in my head, but I may have accidentally left out some important particulars of this kind of mod, so please ask any questions you have. Because this mod relies on the strings below the bridge in a floating tailpiece guitar, I don't think it would work on most solid-bodied guitars, but if anyone can come up with a similar mod for the more common bridge type, be my guest. Also remember that the "clamp" below the bridge cannot rely on the tensile strength of the strings, as not only are they not terribly strong, their tension needs to remain intact so that the guitar can be played in tune.

Topic by Impasse    |  last reply


A Transatlantic Tunnel, Hurrah!

Deep beneath the Atlantic Ocean, forgotten for the best part of a century, lies a tunnel linking London and New York.It was built on the whim of a Victorian inventor with the aim of linking two great cities and developing the kind of friendship that still exists today.But bad fortune befell the venture - and the tunnel lay idle ever after.Until today, that is.One end of the "tunnel" emerges next to Tower Bridge on the banks of the Thames in London - the other is next to Brooklyn Bridge on the banks of New York's East River.It looks like something HG Wells might have imagined.Each end has a giant telescope-like construction which appears to punch its way out of the earth.There are dials, and levers, and thermometer gauges on the side of the 20m long brass and wood construction.Peer into it and you can see people on the other side of the Atlantic.Wave at them, they wave back at you.Web-cam it ain't, but the Telectroscope is fascinating. I hope it's stays operational for quite some time.Telectroscope websiteDaily Mail articleBBC StoryBBC Video

Topic by Kiteman    |  last reply


Violin problems? Answered

I bought a low end, craiges list violin. It was no doubt intended to be a rip off, the violin guy at a shop told me it was made of ply wood. He strung it for me, reset the sound post, and put up a new bridge. It dosn't make sound though, I've been trying to figure out if its the strings (they're not 'coiled' like a guitar string, Ie. E,A,D,G) Or if its not getting enough Rosin on the bowstrings, I dont know a darn thing about how all of it works; but my research these days is telilng me it might be the rosin application, I know your supposed to put a bit on new bows (which I have an new bow) Im going to try a few sugjestions. Any ways; the rosin I have, is a light colored, hard, slightly-larger-than a quarter, circular peice. Its quite hard, and isn't very sticky. Advice is appreciated. thank you! -Adam

Question by ARBenjamin    |  last reply


High voltage discharge capacitor help?

I recently got a 50uf 2000 volt polarized pulse discharge capacitor to blow stuff up. I tried to charge it with a microwave transformer rectified by a single HV diode, but that did not work. My plan was to fire up the microwave transformer, close HV switch #1 to charge the cap, open HV switch #1, and turn off the microwave transformer. Then I would close HV switch #2, and would send power to "load", in this case an orange (see diagram). However, when I closed HV switch #1 (which is a nail in a piece of wood and a rod on a PVC pipe), I would get arcs. Then, when I closed HV switch #2, nothing happened. I even tried shorting the cap with a rod, but it had not charged. Before this test, I tested the capacitor by charging it to 120 volts and it worked fine (I got a spark). Also, there is no internal resistor to discarge the capacitor after a long period of time. Should I try a full bridge rectifier with 4 diodes instead of a single diode? I will also include a schematic of the circuit (you might have to zoom in in order to see it).

Question by TimTD    |  last reply


Looking for Help! 120v ac to control variable speed 90v DC motor Answered

I'm at best a novice when it come to electrical and circuits so if what I've put together is a total disaster maybe you can inform me on a better solution. I've taken a treadmill that was given to me and salvaged the motor control board along with the 90v DC motor the control screen on the treadmill was smashed so i didn't bother to keep it. After a few days of googling and YouTubeing I ordered a scr motor controller but it was only single phase 220v... we here in Canada run a double phase 120v.. so to the best of my ability I wired up the single phase with a rectifier also purchased online. As I would flip the switch the motor would come on full tilt at what I'm assuming would have been 160v DC..I decided to scrap that idea. So after more googling and youtubing I found a page where someone had cut parts out of an old circuit board and just used the main circuit that took ac power in and DC power out.. so I figured I'd give that a try... and of course that didn't work either hens why I'm here writing this now. so I thought to my self, well what if I take the main components like the transfomer (tested the transformer to 120v on primary and on the secondary i was reading 18v av onmy multimeter) to step my power down the bridge rectifier to convert to DC along with a capacitor to clean up the ripple and a potentiometer to control the voltage. I wired these items up roughly then pluged it into the wall and when I flipped the switch nothing caught on fire so I figured I'm off to a good start, but as I started to turn the dial on my pot nothing happened.. until it was turned to the very top that was. then the motor started to turn probably at about 14rmp now I plan on using this set up for a wood lather. Am I going about this like a total buffoon? any help would be greatly appreciated

Question by JamieGmoyer    |  last reply


Summer Camp seeks proposals for ambitious collaborative project

Calling all Engineers, Designers, Sculptors, Builders, Videographers, Architects, Artists and Makers of all descriptions and disciplinesSUMMER CAMP SEEKS PROPOSALS FOR AMBITIOUS COLLABORATIVE PROJECTSBeam Camp requests project ideas for 2009 and future summers.You supply the plan and vision. We'll supply 100+ energetic campers and staff and 700+ acres of forest, mountain and lakes as studio, canvas and workshop. Submit your proposal to be Beam's 2009 Project Master. THE PROJECTEach summer Beam commissions a Project Master to design a unique large-scale collaborative endeavor that campers produce and enjoy. The Project can range from the conceptual to the structural. We are looking for big ideas that will challenge and excite our campers and staff. Our Project Management Team will work with the Master to "translate" the Master's project blueprint into the camp context.THE CAMPBeam Camp is a 4-week summer program (July 18-August 16) for boys and girls aged 7-17 in Strafford, New Hampshire. Beam Campers cultivate hands-on skills while exploring innovative thinking, design and the creative process. They transform ideas into artifacts and personal achievement into community success. Teams of campers work on different aspects of the Project each morning. In the afternoons, they participate in Domains, mini-courses in arts, athletics, science and nature studies.Project CriteriaMake it big.Don't limit yourself to "camp-y" themes.Construction can be a central component, but doesn't have to be.Past Projects:2005 The Nexus Canopy: a raised, 42' x 36' grid of wood and fabrics that the campers transformed from shelter to maze to movie theater to art installation to banquet space. Project Master: Fabian Jabro/Standard Architects2006 The Beam Fleet: seven wooden vehicles, designed, and built by the campers, equal parts kinetic sculptures, simple machines and rolling canvases. Project Masters: Steve Gerberich & Nathaniel Leib2007 The Beam Micro/Macro Domes: five geodesic domes based on the forms and structures of virus proteins, that became shelters, sculptures, playspaces and activity centers. Project Master: Caitlin Berrigan2008 Jungletopia: three tree-houses ring a 16-foot armature to form a play/contemplation space that bridges (metaphorically and physically) Beamers' imagination and craft with the forest environment. Project Masters: Jan Drojarski & Jon BockselFAQsHOW DO I SUBMIT A PROPOSAL?Go to http://www.beamcamp.com/project-proposal/ to fill out the Project Proposal form or send an email to brian@beamcamp.com.WHAT'S THE PROJECT BUDGET?We generally spend $10,000 on Project-specific materials including any necessary new tools/machines.WHAT ARE THE MASTER'S TIME REQUIREMENTS?Upon selection of a Project, Masters have until May 1st to create a blueprint or working plan for the project. We ask that the Master be available for at least two pre-camp planning meetings and join us for at least three days during the camp session.DO I GET PAID?Project Masters receive a $2,500 stipend plus reimbursement of travel costs. Proposals due: March 1, 2009.For more info on Beam: http://www.beamcamp.comFor further inquiries contact: Brian Cohen: brian@beamcamp.com

Topic by Brian Cohen    |  last reply


Pier 9 is Disneyland for Makers

The amount of resources this place has is impossible to describe. If you really want to learn all the equipment at Pier 9 it will probably take you 2 years to fully know how every machine works. People here love making things and it felt like home. For me making is not only the transformation of the object into the final piece but it's a transformation in me, how my emotions change as I build. I never felt more connected to my work as in Pier 9. It's been a few months since I finished my residency and to be honest every week I think of quitting my job and going back. It has been one of my most memorable experiences in the past couple of years and if you are thinking of applying, stop thinking and APPLY! (3 good friends: John, Xander and Wei are now AiR after I shared my experience with them) I applied to be an AiR because I had a bunch of personal projects I wanted to make and had been really busy working at SRI designing really amazing robots to "save the world". Most of the projects I was working back at that time were kind of long and most of them involved DARPA funding (confidential- can't talk about). In contrast, I wanted to make shorter projects, just for fun. Pier 9 seemed like a perfect place. It is located over the water, you will be literally cutting wood on the table saw with the most amazing view of downtown SF. I live in Menlo Park so I would take the Caltrain and get of at King St. Then I would bike for 10 minutes along the Embarcadero. At night, I would bike facing the Bay Bridge Lights. Overall beautiful commute. When I joined in November 2013, things were still being organized at the Pier. For example, making a reservation for a class was super easy and intuitive. a few months after that there was a more complicated process and it felt the classes were always full. The AiR lounge/office had white walls and no furniture so I decided to make a few projects to make our space a little nicer. I also made the AiR wallet to keep the credit card safe (we used to have a big clamp to store our credit card). One final addition, was the AiR roster that I pulled together to know all of the other AiR and have their contact info. One of my objectives at the Pier was learning to do CNC. I started working with the ShopBot and learned to do 2.5 CNC fairly quickly. I enjoyed making CNC furniture for the Pier. I hope the Piggy Coffee table is still in the AiR lounge. After that I continued working with CNC and made a clock and a sunglass case. I wished the DMS 5 axis was running before I left the Pier so I could make my lounge chair from a tree trunk. I do want to say sorry for all of the router bits I broke, all of the toxic materials I used and any other unethical things I've done! I will miss Pier 9 but I what I will miss the most is the people. There were about 10-15 Artists in Residence at any given time. That meant that every week or two, a new talented artist was joining and another one was saying goodbye. The best part was that we all shared our work and got great comments and feedback from the rest of the group. The amount of creativity and diversity was unbelievable. I have to make a special mention to my shop teacher and friend Sean. He has been a great companionnon several all nighters at the Pier. We would be doing some crazy amount of work in the evening and going to bed around 7 am. I would go and sleep for a long while but he always had to come back to the Pier and teach a class. Sean was responsible for teaching me some tricks on a couple of machines so thanks to him my time was more effective. Another thing I will miss is going to the woodshop and see Sam working on the next modification to the shop. He was always with a friendly smile giving us advice while he was finishing his project. I also would like to thank Taylor Stein and Arthur Harsuvanakit. Both work at Autodesk and they have tought me and a bunch of AiR how to use some of the Autodesk software. Last, another thanks to Randy Sarafan, he also was another late night worker and companion. Thanks again to Noah and Vanessa for making my dreams come true. Alejandro (alepalan)

Topic by alepalan  


Tesla's earthquake machine - revisited!

Nothing is better to beat isolation boredom than a good science puzzle.It's been centuries since Nicola Tesla was claimed to be responsible for a minor earthquake caused by one of his inventions.We can be quite sure the actual earthquake was just a coincidence that happened duiring his experiment but still...Inventors and scientists alike have tried to figure out how his appearently small and simple device could have caused effects that can be felt by people.Now it is time to reveal a possible way how Tesla might have done it.Harmonic vibrations are what cause structural things to swing, a reason why soldiers will never cross a bridge with the steps in marching sync ;)The famous London bridge was a modern example on how seemingly randomly generated pushes by pedestrians create one syncronous motions by all of them.You can replicate the effect with a rooling board that has a bunch of metronomes placed on it.Set to the same pace they will start more or less out of sync no matter what you try.But after a few minutes the moving board brings them all in perfect harmony.The above examples and a modern vibration speaker made me think...Tesla used terms like "airspring" and "harmonic coupling" to describe how his machine worked.We know Tesla did not use written notes and that his understanding of science was a bit different.Magnetism wasn't new to him.My proposal for anyone to try is this approach of his earthquake machine:We use a T-shaped housing with a mounting plate at the bottom.Inside is a hollow tube construction.Either side of the T in the top is an electromagnetic coil.Polarities of the coils are identical.In the downgoing pipe we have one magnet mounted at the bottom and another, smaller one in the top - the middle of the horizontal part of he T.Between them is a cylindrical magnet.The upper and lower magnets are selected or machined to keep the moving magnet centered.Preferably in an equal way, meaning the weight of the moving magnet should be compensated for by the other two magnets.The tube shall be providing a tiny air gap around the magnet - enough for a free movement but small enough to provide some air resistance.We created the airspring ;)At least if the tube is properly sealed.Theory of operation:In a vibration speaker we use the weight of the magnet and housing to transfer soundwaves onto a surface.This is a forced coupling that relies on the weight and inertia of the speaker assembly.A sinewave fed into our linked electromagnets will cause the magnet in the tube to move up and down with the amplitude of the sine wave.Electronics side of things:Tesla was a genius, I am not, so I need to cheat a bit now.With the moving part solved we need a way to syncronise our coils to the movement we need.In the most basic form by a simple sinewave generator and audi amplifier - helps to create 4 or 8 Ohm coils ;)However, to make it work in harmony we need one or two hall sensors.The sensors have two functions.Firstly they help to provide the right amplitude for both polarites to get a really even movement from the magnets neutral position.Secondly they provide the feedback to find the harmonic frequency(ies).Like the push-levitating platforms we need a PID control for the coils.The reference comes from the hall sensors like in the platform.Calibration needs to be done on a rocksolid surface.The calibration ensures the magnet will always move in a perfect sinosodial motion - in sync with the coils.In normal operation the hall sensor(s) will monitor the difference between set value and reality.The difference is used to adjust the frequency in small steps.Operation requirements for the electronics:During a frequency sweep the required amount of energy required to get the set movement of the magnet changes.The closer the frequency gets to resonance the less energy is required to push or pull the magnet.Like your kid on the swing.You would try to push when the swing is at the lowest point, you wait until it is just about to change direction ;)The sweep can locate one or several resonating frequencies depending on the set frequency range.The one causing the lowest energy requirements is usually the best.With the resonance almost figured out the electronics now start a fine sweep near the found frequency.From then on the frequency is adjusted to track the point of lowest energy consumption through the PID control.Detailed explanation:With the surface the device is mounted onto starting to swing the magnet becomes weightless at resonance - every time it reaches the top or bottom end of the swing.This means we need to adjust the sinewave so the coils only provide a push right when the surface starts to move in the other direction again.We also need to make sure this push is short and ends when the surface swing together with the coil push moved the magnet to the bottom - the surface push shall keep it here in freefall so to say.In theroy short ramped pulses would be sufficient here.Limitations of the design:As we still have no clue how Tesla create friction free air springs and can only guess how he found and tracked the resonant frequency we face several problems.1. The possible amplitude or lenght of the vertical tube is limited by what the coils can provide in electromagnetic field strenght.The need to be able to pull the magnet from the lowest point as otherwise the frequency sweep is very difficult to accomplish.2. Weight and lenght of the magnet.Ideally you want the biggest cylindrical magnet you can find.Realistically you need one that has a weight the coils can handle properly.No use having a 2kg magnet if then you need coils the size of door holding magnets.So going a longer and thinner might be the way to go.I found a ratio of 1 to 5 suitable, 1 to 3 still works but causes a lot more sideways push on the magnet and through that actually more friction than a longer magnet.3.Ventilation...You will notice that at very low frequencies there might be a "delay" caused by the air pockets either side of the magnet.If you can't ge a suitable air gap between magnet and tube it is often better to have a snug and friction free fit and to add venting holes either end.If the above three points are addressed and matched properly it is literally like you pushing a swing - the limit is the energy you have to push.Good thing is that we don't need to support a circular motion ;)That means the device is mostly only limited in what is possible by the electronics and code.More severe and vital to consider is the last part:Placement limitations:Imagine you want to test the device on a vertically mounted beam with sturdy support either end.The first harmonic would cause the center of the beam to swing but also means the ideal placement of the device would be dead center.In the center the device can support the movement in an ideal way.Place it half the center distance to the mounts (1/4) and the push from the device is far less effective.Furthermore you risk adding sub harmonics thanks to the uneven pressure on the beam.If used as a subwoofer to make your wooden floor shake during the action scenes of your favourite movie you would of course aim for a more hidden placement that would require to find a harmonic frequency that causes the desired effect in the right area of the floor.As a "destructunal" device you would need to find the resonant center of the structure and the frequency where this structure is able to transmit and amplify the motion throughout everything that is structural.Makes it quite unlikely to work as an earthquake machine but still can cause some interesting effects.Ok, if all this relatively easy to accomplish with some cheap electronics and a 3D printer then what about reality and physics?Before you go overboard on the testing and coding try a simple surface or vibration speaker with a suitable amp.Don't use the suction type thingies that use batteries, go for the bare driver (speaker).The amp shall be able to produce and work at frequencies down to below 20Hz.Sounds impossible but I had good luck with dirt cheap 25W car amps that have a 3.5mm audio input on top of the stuff for the car stereo.Most phone with a real headphone output are capable to be misused as a frequency generator.Mount the speaker onto a suitable testing surface, preferably centered.If you happen to have one of these tables with a glass sheet as an insert you can cut a plastic or steel shet to fit in there and add some window sealing tape to act as a cushion.Start at about 10kHz and adjust the volume so you can still tolerate the noise.Move the frequency down and you will notice that at certain frequencies the volume seem to go up quite hard.These are resonant frquencies that cause harmonic waves to form on the sheet.The lower you go the bigger the "spacing" between these waves become.When you found the one that causes a single wave to form on the shet in a suitable direction you will get a rather violent movement of the sheet.It will be required to crank the volume up the lower you go with the frequency.At around 50Hz you should hear this a an annoyingly loud humm.What works with a speaker works even better with a dedicated device that can accomodate for a growing amplitude on a surface and only uses pulses at the right time to move the weight around that causes the push.That means we can only fully utilise our device in stuations where we can match the device capabilities with the structure or surface in question.It is not hard to destroy a pane of glass with a surface speaker and the right right frequency but much harder to make a complex structure vibrate as intended.A very rigid structure with measures to prevent the swinging of supporting structures, like a building, is unlikely to fall in sync with the device.Ever seen these rope or banner swingers in action?They can create amasing shapes by their harmonic movements.Imagine how the rope or banner would look like if there were lots of overlaying swings at different frequencies - that is what you wuld have to fight and eliminate.Fear chamber anyone? ;)Subsonic vibrations are quite easy to do with such a device.And some people say that certain low frequencies make us feel unwell, even haunted.If your house is made from plasterboard and wood then why not transform a wall or the floor into a subsonic speaker?Imagine your next Freddy Krüger night with friends....Crank the volume up every time it gets scary and your friends won't know why this fun movie suddely makes them feel so scared LOL

Topic by Downunder35m  


Ultrasonic soldering bath

Making a working ultrasonic soldering iron is not as easy as I though it would be.Finding tanrsducer of suitable design and size is even harder.So I thought I start with something easier and share the thoughts here.If you need to solder impossible to solder things then quite often you could get away by wetting the entire area.For example the end of a wire or a lug where it won't matter that you can solder on the bottom as well as the top.Back in my days flux core solder was a rare and very expensive thing to find.So we had a little soldering pot and flux pot instead for working with lots of wires.Dip, dip, done....The pre-soldered wires where then easy to work with and the ramaining flux on then was enough.Doing this for metals like aluminium, stainless steel or even ceramics seems impossible at first sight.China offers cheap ultrasonic transducers including the required driver electronics for very littel money these days, despite the trade wars.The most obvious solution would then be to get a cheap and big enough soldering bath and to attach the transducer to it....Won't work though and if it does then not for long.Problem is firstly the heat transfered to the ceramic parts of the trandsucer and secondly the fact that most of these soldering baths use quite thick steel for the container.Add the that you deal with quite some grams of molten metal and you know where I am going.Building your own ultrasonic soldering bath to solder the impossible with ease!Project costs:40kHz transducer with driver board : about 50 bucks.Thin walled stainless steel bowl ( about 50 to 100ml but go bigger if you like) : about 2 bucks.Leftovers for an enclosure can be wood, plasic or your favourite 3D printer.Ultrasonic horn: About 500 bucks from your favourite engennering company or you need to make it yourself - I prefer the later.Main design considerations for the horn:We need something to keep the heat away from the transducer that also amplifies the power coming from it.That is why we can use a bowl or container that has a small bottom daimeter as the transducer if need be ;)There is a good reason a commercial horn costs a lot of money.They are preferably made from titanium and they need to perform as advertised right from the start.We substitude by using some aluminium round stock and a lathe.It is advisable to leave the transducer as it is!Do not take it apart to mount your horn directly onto the ceramics!Use a long enough set screw or include the required thread on your horn to mount it onto the transducer.If you prefer to use stainless steel doe to the lower heat conductivity then be my guest.The horn should have the same diameter as the mating part of the transducer for a quarter of the wavelength of the transducers frequency in the given material.Please look up how fast sound travels in your choosen material and calculate it properly.Having the lenght of the thick part right is quite cruicial.The thinner part that amplifies our movements should be about a quarter of the diameter of the transducer.For example: if the mating face of the tansducer is 40mm in diameter then the thin part of the horn should be 10mm.The length again is a quarter of the wavelength or the same as the thick part.Where thick meets thin please allow for a 3 to 5mm radius and make sure this area is nice and smothly finnished.Now, length is quite critical here....As we will mount our finnsihed actuator free hanging under the bath we need a feasable way to comapensate for our tolerances by creating our horn without a simulating software. I found that welding a short stub onto the container works best but with aluminum it is harder.I assume most will opt for welding a 6mm soft steel threaded rod onto the container.Either way the container surface must be kept flat for the mating surface of our actuator rod.So it is best to make the stud yourself or to use a suitable replacement - like using some flux and your stick welder for create a makeshift spot welder ;)If you decided on using steel for the horn then of course you can just mill a 10mm piece with a suitable thread and flat mating surface...What you want to end up with is a screw connection that has a flat mating surface and no empty spaces, fine thread prefered.Tuning the horn....The ensclosure is easy to make as a box, so the only thing to worry about is insulation but nothing to affect performance.So I just assume you have it all ready ;)With the horn at one quarter wavelength either end our thin end will be too long unless a short stud is used for a direct fit.So whatever you had to add for the part on your container or bowl need to be removed from he horns thin end.Try to keep the gad for the threaded part as small as possible as it affects the resonace.As things never turn out perfect the first try I prepare some thin steel washers - 100mm outer diameter in case you wonder and stick with the above example.I use a strong neodymium magnet and belt sander to create washers from very thin to slightly thinner ;)Taking off slightly more from the horns end will then allow toadd these washers if required - but please do a try as it is first when you think you got the measurements all right!For an aluminium horn you will of course use aluminium washers here.To do so fill the container with some water and place a sheet of thin alumiium foil on top of the water.Turn it on and within a few seconds you should see holes appearing in the fiol or even small fractures.If nothing but noise happens it is quite certain your rod will be a bit too long.Unscrew and take about one tenth of a mm off the thin end of the horns mating surface to shorten it.Try again with the foil and if no better remove some more material.Once you see some action try adding a layer of aluminium foil between the mating surfaces - screw it tight!The foil won't last long but if the action on the water is far better until it fails you know you took off too much.The washers come into place if the tuning won't work at all.Sometimes you can cut off a little bit again and again but the piece will remain too short ;)Especially if you have an aluminium horn and needed to use a steel screw on the bowl...So once the shortening of the horn fials you add a washer to get slightly above the original length and start replacing the differently thick washer until you find a sweet spot.The tricky part is over, now to solve the heating poblem...Using some glass seal as used on wood fire ovens not olnyl provides good insulation to our enclosure but also prevents the vibrations from spreading too far.As our hardware store won't just give use the little bit we need the rest can be used to insulate our container.Dending on the size and shape of your container I hope you decided to buy a container tha fits your heating element...I found that replacement coils for lab heaters work fine but some small fan heaters also use round heating elements instead if wire spirals.For a custom shape it is quite easy to use a coil of heatin wire rated for your mains voltage and a glass fibre sleeve for insulation.To keep it all in shape just wrap some steel wire over it - over the insulated coils of course.The temperature control can be as fancy as with a microcontroller or as simple as using a dimmer like I did.Most heating elements will go glowing red hot if the mains voltage is not reduced.It makes sense to limit the dimmer's movements accordingly by testing it.Just do it in the dark afeter exposing a small bit of the heating wire from the insulating sleeve.Once you see a faint glow coming dial it back a bit until you can see any glow - that should be the max setting.For a big bath or to save time you can of course crank it up to what the glass insulation can tolerate but be aware that solder can boil over!I do a temperature check either with a touch free IR thermometer of by checking how quickly some rosin boils off.If you need to dip bigger parts you need a higher temperature, so I think a digital or sensor temp control is not really required.Once you found a sweet spot to hold the solder temp long enough without getting too hot or cold just mark it for reference ;)Using the ultrasonic soldering bath correctly.Cavitation is what the work for us, so we only need to activate the ultrasonic part when we need it with a push button or food pedal switch.We do not use any flux or resin!That means if you used the bath for normal soldering and or resin then clean the remains off the surface first.A shiny and clean surface is best but the oxidisation will happen quickly so don't be too disappointed ;)Start by dipping in a clean copper wire.Some solder might stick but it won't look proper.Now dip it in again and while it is in push the button for about 3 seconds.Like magic, if tuned properly your wire is soldered and properly covered to where it was dripped in.Try the same with some slightly sanded or at least clean aluminium wire, but use the button right away for about 5 seconds.The wire should be coated with solder once more.You can try a glass rod or some stainless wire next but I guess the working principle is clear now ;)Not everything will bond with solder, especially not if it is not clean.A piece of glass with your fingerprint on it might just fail and some ceramics will only let the solder stick without actually bonding.You should always check the mechanical strength of your soldered connection before having to rely on it ;)And why would you need such a machine?Well, most people won't have any use for it.Those who do might not be able to afford a commercial model.And there is always those who just want it all...If you know why you need such a thing than you have an alternative now at a fraction of the cost.You only need a lathe or someone who can machine the horn for you.Another benefit is that for smaller containers it is possible to weld a small "bridge" over the top.Should be placed so the bottom is in the solder while top is above it.In many cases you will then be able to use this plate to heat up whatever you need to solder on.Like a glass plate where you would like to solder a wire to.Once up to temp turn the ultrasonic part on and use a normal soldering iron and flux flree solder.Works quite well for these small solar panel kits...Ok, and how far away is our cheap ultrasonic soldering iron?Not that far :)I already have a topic for this though....

Topic by Downunder35m    |  last reply


Ceiling fan generator mod to the max

I stubled upon several mods to convert a standard ceiling fan into a more or less usefull generator.So if you are looking to go this route then I might have some nice improvements that can be implemented.People like these mods for some weird reason, despite the fact that it requires quite a bit of extra work to make them weather proof.However, when it comes to the fundamentals then to me it looks like some folks out there are missing out.On the available power that is...Always the first step for a mod like this is to replace the induction ring with a lot of magnets.Second step usually is to remove a lot of the coils, especially the inner ring.Now, these two stator designs are common for fans with two speeds.Those with three or even reverse might have a different configuration!Lets start on the magnet part:The recommended way of placing the magnets is by creating an air gap as small as possible - makes sense.But then it is always the same amount of magnets as there is coils - and the spacing is also the same as for the coils.In the general generaotr design world this configuration is prefered as it allows for the best performance.If you dare to go a bit further and cosider how the magnets react to the stator configuration then you might want to consider a different option.You see, these two sets of coils for two different speeds mean just one thing:A different amount of poles is created, with the outer ring having more poles than the inner ring of coils.The core is split around the coils, not just to allow the windings to be made but also to provide independent paths for the magnetic field - resulting in the two pole configurations.Amounts differ by diameter, power level, manufacturer and so on.What is always the same is that the inner ring has less coils and that the outer segments of the poles created have even spacings.In the normal mods you see posted these gaps in the core for the outer ring are closed by inserting lamitaed pieces from some old transformer.And you end up with ONE usable coil configuration and ONE power output.The slightly advanced mod uses the inner coil to add some load depending on the speed to prevent spinning out of control in high winds.If you try a normal DC motor with permanent magnets than you will notice the strong binding forces, it is like the rotor sticks in certain places.The better ones use and uneven configuration to reduce this binding effect ;)In my mod the magnets are selected in size to almost be the same length as two stator poles next to each other.This allows for the best induction while still allowing "to experiment".Bringing the magnets and the coils into play...As said an exact match of the number of magnets to either coil ring is not ideal.The prefered option is to go somewhere in between.For example:Outer ring has 18 coils then the inner ring will have 9 coils - exactly half.360° divided by 15 make a nice 24 degress per magnet.But with 12 magnets you get an even 30°, which is far easier to deal with.16 magnets at 22.5° is another option.So, what does that exactly do for us?The bad thing is we get slightly less performance if you only see the standard mod with one coil ring.The good thing we get far lower binding forces and through that the thing will even spin in very light winds.Adding both coil rings with a suitable rectifier however results in a pulsing output of two sine waves.With just the rectifier we get a ripple that is easier to deal with through a capacitor.The extra power available is in the range of about 40% and make more than up for the "reduced" amount of magnets.Going the extra mile once more ;)Having created a much fancier ceiling fan mod now you might wonder if there is not a way to get even more out of it.And there is.For example by utilising a gear system or belt to get a far higher rotational speed on the generator than what the blades would provide, prefably then with quite big blades too and an automatic break for high wind conditions.With the reduced binding forces the generator will be happy to spin at quite high speeds in low winds.Downside is that you will need to build a far more sturdy bearing housing.In return though you get more stability and durability.You can do the math yourself based on the number of poles per ring and magnets to get the output frequency based on the RPM's.Perfect would now be to use a switch mode power supply configuration to directly transform the provided output into a stable DC per ring.And yes, it is possible to use mechanical systems to provide a fixed output speed from the blades to the generator - but way to complex and lossy!Lets do some lame math with no regards to realities:If the original fan would spin at 100 RPM at full speed than we could say our generator should provide the mains voltage at about 100 RPM.Keep in mind we utilise both coil rings and not just the high speed one!Geared and with the blades spinning at 100 RPM we might get as much as 1000V from this little generator....And even with the lower amount of magnets we migh see frequencies above the 500Hz range.The good thing now is that normal iron core transformers can still operate at these frequencies.A bit lossy in the upper range but acceptable for the purpose.Put simple: A 10 or 20:1 transformer per coil ring would provide us with a far more suitable output voltage and much higher amps.If you made it to here than you certainly wonder about other magnet configurations.Checking the stator configuration you will by now realise why I selected the magnet lenght accordingly.The magnets "activate" one coil after the other.The spacing between them means there is always some overlap where the magnets only cover one half of the stator for a coil.This is ok because we don't really have to worry about the resulting messy output.Ideally though you would want to have a magnet activate both coils, the inner and the outer at the same time.What we did though was to make sure that at no time more than ONE magnet fully covers more than ONE coil!It is the best option to cover both coil sets while minimising binding effects and increasing the avialable output.To go the last step you would need to invest a lot of time re-winding all coils :(You don't want to do this unless you have the means and no friends and family that might miss you for a few days....I found a far simpler way to change the coil configuration, although it is not as good a re-winding.So let's go full scale shall we?Ceiling fan reconfiguration!If you take the usual 18 to 9 configuration than one thing jumps to mind reight away: 3-phase power!Cutting the wire that goes from coil to coil might not always be possible and if it is then you need to know how to handle it.Magnet wire can be hard to solder.Burning the coating off results in corroded copper that is even harder to solder.If you are lucky though than a reall hot soldering irong will be able to melt the coating.The flux from the solder will start to cover the wire from the cut and the solder will follow.If not then using some fine sandpaper and time is the other option to remove the coating...Ok, you seperated all coil and have two wire ends per coil?I hope you did not cut off the ones going out to the actual connections to the outside world ;)Properly solder each wire end and take your time to check it is really proper and not just a few spots.Mark or number the coils on the rings!For the inner ring we have 9 but need only 3, so we start at one connection to the outside world and check if this connection is on the outside or inside of the coil.For this example I assume you picked the one that goes to the outside of the coil.Connect the inside wire to the outside wire of coil number 3, assuming we start with 1 here ;)From the inside wire of 3 you go to outside of 6 and the inside is you first new output connection.Do the same with the remaining 6 coils and where needed add the required output wire.It really helps to have wires with three different colors here, one color per new coil set.Note which color corresponds to to the three coils used!!!The outer ring with 18 coils is sightly different here.You see, we want a "flowing" magnetic field that makes best use of the new coil configuration!We can not simply bridge them in any way we feel like without considering how this might affect the electrical side of things.As we now take the approach of a three phase system it makes sense to use a more suitable magnet configuration as well.So before go to the outer ring of coils lets have a look of the best option for the magnets first:The stator packs are evenly spaced in our example and will alow us to use 18 magnets.This provides the best performance with the downside of a higher binding effect, but we need this configuration to get the best possible output.As said at the start I selected magnets that are just shy of being the same length as the corresponding stator segments.In a "free" setup these magnets would now be quite hard to place in a makeshift ring.Even harder in the original casing.A 3D printer certainly helps but some common sense too ;)Wood is easy to work with and if you select the right stuff than making a suitable ring to hold your magnets and attach to the drive system metal parts is not too hard.Bar or brick type magnets can be quite easy be utilised on a wood setup :)The key is that you add Flux Capacitors - sorry couldn't help the reference to Marty....What I mean is to add some magnetic material between the north pole of one magnet and the south pole of the other.Lets say your magnets are 15mm long and have a spacing of 5mm.Then a little plate of 12mm would be next to perfect.This plate needs to connect the magnets on the backside, the side facing away from the coils.Use a dremel tool or what you have to first create slots for the metal strips or bars, then the same for the magnets.Glue in the metal first and once set add the magnet, making sure the always go north to south with their alignment.Ok, and what does this do for us?I hope you are not one of these persons who starts building while reading...What we created now is a shortcut for the magnetic forces.The field between the magnets is severly compromised in terms of being usable for the coils.We do get a much soother run though...I only did that to have some fun and check if you paid attention - sorry :(What we really want is an effect similar to what you see on a loadspeaker magnet that is still in its metal shielding.A ring magnet with one pole on the inside and one on the outside is used here.The shielding provides a path for the magnetic field that is not going through the speaker coil - hence the little air gap for the coil.If we do the same then our efficiency will be going up quite a bit.Take two identical steel parts, like some butter knifes, and prefarbly a force gauge.If you try to pull your magnet at a 90° angle from the blade you will get a certain reading for the required force to lift it off.Most people now think that this would be the max a magnet can hold.So take the other knife and place the magnet between them.If you pull the knife off with the gauge now the reading will be higher than what you get from just the magnet ;)Taking that to our model and keeping the field lines in mind we now know that we could even use slightly longer plates if our magnets happen to be a bit short :)Just place them right behind each magnet !Back to the outer ring of coils....With 18 magnets we get an even system for both coil rings.However we want to make sure that our output waves are syncronised and not at random order.We need to combine two coils to be back on a 9 coil configuration as on the inner ring.The other option is to provide two sets of outputs for outer ring, resulting in 3 3-phase outputs.Both have their pros and cons....But if you check the 18 magnet configuration ina ction over the coils it becomes clear that combining two coils the usual way is possible but also that our inner ring does not get a proper north south action from the magnets!Only the outer coil ring works properly!For the inner ring we never get only a north south combo, instead a lot of mixes.Did I mention to read first? ;)Of course we can only use 9 magnets in our configuration, but at least I did not traick you on their size....You see, we need to account for the fact that the coils are not just evenly spaced but also that all configurations in terms of coils to stator pack are doubles or halfs.Makes a lot more sense if you know how these asyncronous motors work :)With 9 magnets we actually get both inner and outer ring coils activated properly.Plus we now have the benefit that there are always twoouter coils in sync with each other.Means apart from the same way you wired the inner ring you make this addition to the outer ring:"One" outer coil is created by going from one coilinner connection to the outer connection of the second after this, skipping one coil.The resulting output is again just 3 phases but with double the output voltage.The key is to again take notes of how you connect and wire the coils - and the colors used for the output wires!Let me give you an example for the correct order:I we take the number 1 coil on the inner ring then coils number 1 and 18 would be next to it on the outer ring.You want to combine 1 and 3, 2 and 4, 5 and 7,....And you want the resulting three coil packs and wires colores to correspond to the inner coils in the same order!That is true for the always same way of combining coils from the inner to outer connection - or the other way around but never mixed!Ok, we have done the magnets and the coil configuration now properly, no jokes this time!With two simple 3-phase rectifiers we get two DC outputs that can be combined or used seperately.As we end up with roughly double the output voltage on one output but all coils are the same it makes sense to treat them independly.For those who wonder why:If you add a load than one coil system would take a higher loading of it.Meaning while one coil set is stll fine the other will already start to overheat - if the load is too great.So we use two rectifiers with some filtering.In the basic form just a really big electrolytic capacitor of suitable voltage or a full LC filer system with multiple stages.Either way we can now utilise some better DC-DC converters to get going.Considering the equal max watss the coil rings can handle it make sense to include some current limiting.A good converter will provide this option.Both converters can now set to the desiered output or with some added protection diodes and adjusted properly to the same voltage combined for just one DC output.Compared to the standard mod of removing coils and bridgning stator packs the resulting output power in overall Watt will now be about 40-60% higher - depending on the model and quality of parts.Special words of wisdom:Consider the orignal max speed of the fan when used as intendet - see this as a theoretical max output that equals your mains voltage.Just ignore losses and such things - better to be safe than sorry.It becomes clear that it quite possible that your output will be far higher than mains voltage and that you need use transformers for the two 3-phase systems so you can use standard DC-DC converters, which have a max input voltage of around 50V only.This means your converter must be able to handle the higher amps!The fan might have only used 100W or less than 500mA but at high speeds and a ratios of lets say 10 to 1 for the gearing high wind speeds might get it up to over 5 amps on the transformer outputs.Please do the math first for your gear system in relation to the max wind speeds you want to use with your blades!If in doubt use a converter that has some reserves to offer, especially if you aim to charge batteries as quickly as possible.The most vital part however is to ensure that all previously cut wires are isulated properly!!!Magnet wire of the standard kind is good for about 1000V max, so don't drive it higher!Heat shrink with a hot glue liner is prefered but hard to apply in these thight spaces.Since nothing moves consider using long enough wires for your connections so you have enough space to solder without affecting the heat shrink tubes.Liquid insulation or rubber is the last option and should only be used to finalside the heat shrink security measures.Best option once all is confirmed to be working fine would be to make a custom mold and to fully enclose the staotr pack and wires with casting resin or an insulating casting mix.Make sure to keep the output wirese free at the their ends ;)What if I don't want to build a complicated three phase rectifier and just use a single phase system as it was?Firstly chances are your coils are already connected in a three phase configuration, just all in series.But working out a suitable magnet configuration to suit this is much harder if you want to use both sets of coils.In a series configuration like the original you also have to accept the losses from these connected coils.The higher the overall resistance the lower the possible output ;)Main problem however is to get the magnet working properly.The standard 9 or here even 18 magnet configurations still works, especially with the added shielding from behind.But the coils also produce a magnetic field, which grows with the load.Means that an top of all you also have the coils working against the magnets and create even higher losses.Explains why the simple folks prefer not use the inner coil set if they go with a single phase system.So either accept the losses and just use the outer coils or do it fully and get far mor output.And by the way: a 3-phase rectifier modlue is only a few cents more than a standard bridge rectifier ;)Ok, and why do I bother to write all this?People like to tinker but most don't really invent.Following some simple instructions is easy, trying to work it yourself much harder.The reward however is that you actually start to know what you are doing :)And what works for a ceiling fan can be used for these ring style washing machine motors too ;)Anyways...We need to get back our roots.Start thinking for ourself again, work things out instead of just looking them up.If people would be aware that a simple ceiling fan could provide about 3 times the output power of its rated installation value instead of only just about half......Super strong magnets allow real output even without re.winding all coils.And what works here works for other things too.We only learned to use magnets in a striaght way because we can not bend them.But we can bed the magnetic field lines to our advantage!The simple shielding used in this mod is nothing more than a shortcut to enhance the field strenght where it is is needed.By a simple coil modification we basically bet two electrical generators for the price and size of one.Apart from stating how easy it would be to place multiple stators and magnet rings into one generator the magnets itself also allow for even more output.If you ever played with hook magnets or speaker magnets then you know how much stronger they are compared to just the magnet once they seperate after hours of fun for you.Imagine you would replace the single bar magnet with two block magnets that are joined by a magnetic shunt like out simple shielding before.If the magnet blocks now would have a slightly smaller footprint than your individual poles:Imagine you create a hlaf ring shaped magnetic connection between the two blocks that also goes aruond the outer perimeter up to the outside of the magnets surface?I mean the surface facing the stator poles?Damn your imagination is good, yout it right away!Of course we would then have a magnet that allpies its full strength focussed onto each pole of a coil!And of course the resulting field would be far stronger than just using the magnet blocks itself and still significantly higher than just adding a shielding or connection between them.The affect of the next coil coming is also drastically reduced, which in return also increases the efficiency.In terms of numbers:If a fixed neodymium magnet would provide us 100$ field strength as the base point with no shielding (just the magnet blocks alone);A fully shielded and connected system, like in a hook magnet combined with a U-style magnet, would reach above 400% here.....Adding witchcraft to the mix ;)Although I know better I just assume some of you have now a working double-three-phase-ceiling-fan-generator.And that would mean you also have some fans to spare from your long experiments.Modern ignition coils seem to have nothing in common with our ceiling fan or resulting generator.So why do I try to use them anyway?For the ignition only one polarity is prefered so the spark works and travels as intendet.Means the "wasted" energy from the othe half of the pulse seems to be lost.The electronics do a lot here but magnets too ;)The core of the coil has magents at either end, turning it into one long magnet that still has the right properties to act as high voltage transformer system with the coils.The coil appear to be pre-loaded and with the ignition pulse it has to overcome the magnetic field pre-set by the magnets.And when the electrical impulse is off the same magnets also accelerated and increase the resulting fall back impulse - which provides the spark.Unless you have a suitable laser cutter or simlar cutting tech available somehow it will be hard to modify the metal plates of the stator.But if you could...Imagine you could add magnet inside the plates that are inside a coil.The same pre-loading would happen.Does not really help in terms of adding outpur as our rectifier would suffer badly here.It does give ideas though...Shielding works fine for the magnets, same for field shaping.Electromagnets use the same techniques...So why not use some leftlever transformer cores to add more "shortcuts" for the coils?Strips of transformer core sheets added either side of the coils increase their field strenght and result in better output!Three packs either side of the stator pack are usually no problem.Now take your leftovers and do a standard mod.Compare the max output on the same windmill with what you get from my mod(s).The only real magic I used here is that I actually bothered to combine multiple and already used methods to drastically increase the available output of an otherwise utterly useless generator mod ;)Warnings:If you take the above mods serious and to the their extreme than it is imperative to make sure you have safety measures in place!Assume the lowest rating for the magnet wire and if in doubt stick with a max output voltage of 800V.These mods are potentially lethal if you don't follow what is common sense to everyone dealing with high voltages for a living!Most people will start without any gearing or belts and use the wind directly.Even here it is easy to get far higher RPM than what the thing ever did under your ceiling.Without some fixes you will need transformers to reduce the output voltage accordingly.Only other option is to limit the max speed to what your DC-DC converter can handle.Making mistakes with mangets can cost you a lot of time and work, make sure to mark their poles somehow to prevent putting them in wrong.If in doubt then double check!Always keep in mind what the magnet wires and your connections can handle!You don't want any arcs or overheating.Some added electronics to monitor wind speed, rpm's, load and temperature of the coils can turn out vital once you upscale.Before letting your new generator do its thing make sure you tested all to the max!Use a drill or so to speed it up and check the limit regulation for the converters.Measure the actual volts and amps going through your coil sets at assumed max speed and max load.Monitor the coil temp while doing so to ensure nothing is out of limit!You are kidding me here right?A scrap ceiling fan shall provide more output as a wind generator than what was used to spin it as a fan?And of course I need not one but two 3-phse transformers...Pretty clear it is all a fake because nobody could replicate any of it unless limited to what the converters can handle...Didn't I say to think outside normal restraints already?A single phase transformer uses two coils in the most basic configuration.For example one side for 240V and te other for 12V.But some of them are more efficient than other ;)A 3-phase transformer uses 6 coils, two for each phase.And there are plenty of standrad transformer cores out there that would allow us to use this configuration.The worst being the MOT, or microwave oven transformer.Very lossy for a reason but good as an example as these have three core stems ;)Now that you see that you will that a lot more transformers actually allow you to replace the two coils with 6 ;)Ok, but why not use a rectifier first and not use a transformer or two at all?The resulting output voltage will without a gear REDUCTION be much higher than what a cheap DC-DC converter can handle.And at such speeds the effiency would be very bad too.You would need huge capacitors of good quality to deal with the now more impulse like output.And considering the primary side of the transformer does not require anything thicker than the wire on the coils of the fan...Not hard at all to find some suitable tansformers to salvage - or to use some nice ring transformers ;)No kidding around, just facts and possible options you might want to explore.Does that now mean I get free energy?Sure, if you mean you get the free nergy from the energy of the wind at no cost.No if you think a ceiling fan could ever power your house.Internal resistance, size and wire/connection properties set our limits.Not to mention that they are designed to be dirt cheap.If you are in a windy region and assume a realistic 300W minimum output from a 100W fan then adding more stage multiplies this.These fancy upright windmills are not just powerful but also would allow to use one modded fan either end.If big enough and with enough wind force throughout the year you could just add a second or third stage to ech end.With 3 on both ends the resulting output would then be suddenly 1.8kW per windmill....And all from scrap parts with only the costs for the magnets...No wind? Then use water....None of it? Get some greyhounds and build a big hamster wheel :)You get the general idea I hope...

Topic by Downunder35m    |  last reply