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Forum Index : Windmills : wind powered comp
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makourain Senior Member  Joined: 19/04/2006 Location: Posts: 111 |
i want to use a deep cycle and use it to run my computer. which is better? * inverter from the battery to power the power supply. * dc/dc converters directly to the different power cords that come out of the power supply. will a smart drive windmill be any good for keeping the battery charged? also, is there a way to cap the voltage to stop it from going above 12.5volts, i dont want the windmill super powering the comp and blowing all the bits and creating a bon fire. |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5019 |
Good question. If its a PC, the internal power supply has to provide several bus voltages, -12, -5, +3.3, +5 and +12. The +3.3 and +5 need to source several amps. There are PC power supplies available that will run on 12vdc instead of the typical 240vac, but these are expensive. See http://www.zantech.com.au/zantech/power-supply-atx-12v-dc/. This is the most efficient option for the PC, but you still need to power the monitor and printer, etc. Or you could use a 500 watt inverter. As its a PC, you can get away with a cheaper modified sine wave inverter, and you should pick up one new for less than $200. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Definately use buy a power supply that runs on 12v. Jaycar sell one. I couldnt find it on there website, but im certain they sell them. You will still need a small inverter for your monitor and any other perphirals you have. |
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| Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Found it! http://www.jaycar.com.au/productView.asp?ID=XC4875&CATID=&ke ywords=XC%2D4875&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword 1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID= Its only a 250watt module though, so its a bit small for the newer Pentium 4's and AMD's. |
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| RossW Guru  Joined: 25/02/2006 Location: AustraliaPosts: 495 |
If you're into a bit of "tinkering"..... I presume this is a desktop PC, not a laptop. Get a "spare" power supply. AT and ATX supplies are pretty cheap. Most of the switchmode supplies take the mains, full-wave rectify it and feed that to the "primary" side of the switchmode supply. The switchmode controller chip has either a feedback winding from the inverter transformer, or a voltage divider tapped from one of the output rails. If you pull out the inverter transformer and (substantially) rewind the primary, you should be able to get the SMPS to provide all the right outputs from the nominal 12V input from your batteries. If the primary has (say) 1000 turns of wire, you will want about 340/12*1000 = 40 turns to run off 12V. You may have to beef up the switching transistor and use a slightly larger wire, but this will give you by far the most efficient conversion - you'll only have one lot of conversions to do. I've done this to run a device using a similar SMPS, off my 48V supply, and it's worked fine. I've also converted computer SMPS PSUs to make high-performance 12V chargers. |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
i am a tinkerer :D and im not made of money so those 2 reasons make me wanna make my own if possible :D i was looking at the inverter project at this link; http://www3.telus.net/chemelec/Projects/Inverter/Mosfet-Inve rter.htm it gives square wave output, is that a problem? [quote]I've done this to run a device using a similar SMPS, off my 48V supply, and it's worked fine. [/quote] any chance of a pic or two? the power input plug to the power supply has 3 connectors, and a car battery only has 2 wires, what do i do about that? also, since a car battery is dc, wouldnt it short out when just connected straight to a coil? also, to beef up the switching transistor what one would u suggest i put in? |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
[/quote] It isn't connected straight to the coil, and the switching (chopper) transistor varies from circuit to circuit, you'd need to look at what was there first. The existing device may be able to handle the current, if not, you'd need to replace it with one that can. |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
ok well you lost me there. on an entirely different subject, how do i convert the power from a smart drive to heating. do i have to rectify it or can i plug in to a heating element? how do i connect it to a heating element. wat sort of element should i use? should i even use an element? im gonna make a f&p wind turbine, im just not 100% sure what im gonna use it for. the one im doing will have 1.1metre pvc blades and will sit about 1.5metres above the house roof, but wont be attached to the roof :) |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Heating works perfectly well on AC or DC. Indeed, if you have to rectify it first, you're losing (wasting) some of your heating energy in the diodes already. If you can wind your generator for single phase, you can use a single heating element. If you have it wound for 3 phase, you will need 3 elements to extract the maximum amount of energy. Lets make the assumption it's a 3-phase (doesn't matter if star or delta connected) machine that can generate 500 watts at 12 volts, you will need a heater element that can handle at least 500 watts, but finding one that will work at 12V might be a bit of an ask. Maths would say that a resistive load on 12V would pull 40 amps to dissipate 500W. Thats about 0.3 ohms An element that is only 0.3 ohms would pull 800 amps off a 240V supply, or 192KW! Somehow, I don't think you'll walk into the local sparkies supplies shop and buy that off the shelf. I think you'll have to build your own. You could probably cut down a jug or radiator element to run off that low voltage, however my next concern is that your cables will be (relatively) long and high resistance, and you'll burn up more power there than you'll deliver to the water tank! Better to wind the F&P for a higher voltage at a lower current, you'll lose less in the transmission, and if you can get the volts up high enough, may even get a commercial element to do the job. Eg, 500W@48V = 10 amps, or 4.8 ohms, or a 12KW/240V element. We're at least getting in the right ballpark, since I believe some HWS use 8KW heating coils. (8KW @ 240V = 7.2 ohms, 7.2 ohms @ 48V = 320 watts) Just back-of-the-napkin type calculations, but you should see my point here I hope :) |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
reason why u lost me is i havent slept for about 25 hours, anyway i was thinking more along the lines of heating me than heating water. it got very very cold last night, with 2 jackets and a water bottle i was still feeling the pinch. theres only one heater and it wasnt in my room. the sort of cord i would be using would be copper about 8 metres long, about 5 strands totalling up to about 3mm or 8guage. it would be 3 phase. i have a lot of bits and pieces here so i think making own element would be easier and quicker and cheaper. the windmill blades, iv got a pvc pipe about 13cm in diametre and about 1.1metres long. i was thinking of cutting this in to 3 lengthways and use that for the blades, with shaping and all stuff, making the ends tapered and having one side rounded and the other side pointy like an aerofoil. i can use some 1mm stainless as the hub for the blades and attach that to the smart drive. ill spin the magnets around the stator :D the pvc is about 4mm thick so how do i go about making my own heating element(s)? |
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