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DC to DC Step Up Voltage

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  • Sam Jennings
    I found this thing on ebay, recently, and had to wonder: DC to DC Step Up Voltage . It supplies constant output volts (boosts to, say, 12, no matter what
    Message 1 of 31 , Nov 12, 2008
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      I found this thing on ebay, recently, and had to wonder: "DC to DC Step Up Voltage". It supplies constant output volts (boosts to, say, 12, no matter what the inputs, and gives the rest as boosted (or reduced) amps.

      http://cgi.ebay.com/DC-to-DC-Step-Up-Voltage-Converter_W0QQitemZ230307144034QQcmdZViewItemQQptZAU_B_I_Electrical_Test_Equipment?hash=item230307144034&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318

      I mailed the guy and he said he has them rated for small wind turbine capacities, as well.

      Does anybody use these things?



      To: small-wind-home@yahoogroups.com
      From: doug@...
      Date: Wed, 12 Nov 2008 17:38:57 +0000
      Subject: Re: [s-w-h] Hub, Gear, Shaft, Bearing, Belt -- Gear Ratio -- project update




















      Hello Sam - I remember your name as though you were a veteran. Yes

      essentially everyone uses a 3-phase Permanent-magnet AC alternator and

      bridge rectifier. I have found it makes more power than brushed DC

      motors, especially since the Supermagnets make up for the low RPM,

      allowing a small genny to make big power! If you do the calcs on the

      centrifugal force on your chain or belt around the small pully, you'll

      find it pushes the limits of chain or belt. Or check the

      manufacturer's specs. I am not saying it won't work, just that I went

      thru this process and had to look around and say "OK this toothed-belt

      thing, and the chain idea, is well-known technology and nobody in the

      industry is using it, so maybe it doesn't work so well."



      I could send you a photo of a very rusty chain for example - hard to

      keep it oiled up there, and bird do-do doesn't help, when mixed with

      daily dew.



      Then again - maybe nobody has given the toothed-belt thing a proper

      chance and maybe it will work fine. And it is not as though no

      turbines use brushed DC motors, but not many, so it is not like it

      won't work - it does work, but what I found is it doesn't work well

      enough that you want to make more of them - then again, you might find

      the magic combination of parts that works great and withstands 100 MPH

      winds. That will be the next test once you're making good power: What

      happens in that 100 mph gust? :)



      You can match the number of poles to the original number of poles of

      the motor which is 2 poles for 3600 RPM, 4 poles for 1800 RPM, 6 Poles

      for 1200 RPM, 8 poles for 900 RPM, etc. (actual rated RPM is slightly

      higher due to "slip".) Essentially you want to match the number of

      poles of the stator. Leave 1 space between the magnets larger than

      the rest of your spaces, so all magnets hit their corresponding poles

      at slightly different times to reduce cogging by a large margin. It

      is far easier than building an axial (cluster?)-flux machine. I am

      told however that "once you go axial flux, you'll never go back", and

      it may be that for a home-built single-rotor design, axial-flux is the

      best way to go, but personally I am trying to make things light

      weight, affrodable, simple, and repeatable. I've found that you can

      get a lot of clues from industry - there is a LOT of accumulated

      experience out there in the field of rotating electrical machinery.



      Doug S.

      --- In small-wind-home@yahoogroups.com, Sam Jennings <samjennings@...>

      wrote:



      > Hi Doug,

      >

      > It's good to hear from you! I don't know if you remember but we

      talked on the phone several years ago. I noticed your website has

      some nice new ideas, recently, including the balloon tethered

      turbines. I had to admire it. =)

      >

      > I don't care about the forum moderation. And I'll pay attention to

      what you have to say. On the other hand I have to pay attention to

      what resources I already have at my disposal.

      >

      > I've proceeded with my plan in a relative information vacuum, and

      now all the parts are en route; I already made the investment. I

      might as well connect all the parts and see how much performance I can

      get, and hopefully without problems of noise or compromises in

      starting speed or burnt out dc motors (with or without teeny wires).

      If there are problems or setbacks I will proceed regardless and

      eventually there will be genuine progress.

      >

      > Doug, your turbines run at a higher rpm b/c of smaller props, right?

      So when you describe the noise problem with belts / chains, are you

      talking about a hypothetical conventional turbine or an ultra high rpm

      turbine?

      >

      > In terms of motor alteration, how do you choose the motor? Any 3

      phase motor? AC / DC?

      >

      > What I've got right now in terms of motors: 2 100 watt dc motors

      (with brushes) (and now also 2 complimentary belt driven power trains

      that I'd hate to waste). & some fan motors (unlabelled, AC, not sure

      if 3 phase).

      >

      > I've also got 30 neo magnets, 42 strength, 1x.5x.25 inch with poles

      on flats, and 3.8 lbs of 22 awg magnet wire, all just waiting to be

      turned into a (brushless) axial flux generator (i've got bearings,

      shaft & hub for the same), but I don't know the right number of coils,

      or how many turns per coil, or how many magnetic poles I should use to

      assure a desirable watt/volt/amperage and a reasonable rpm without

      risk of burning up my coils. Is that a reasonable use for those

      resources, or am I better off looking for motors to convert to pm

      brushless (using those magnets)?

      >

      > And I hope this isn't a stupid question, but does anybody use AC

      motors to generate, and then use bridge rectifiers (for instance) to

      get DC for storage to battery?

      >

      >

      > Sam

      >

      >

      >



















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    • Ian Woofenden
      A few list users have expressed concern about the lack of list activity. I suspect it is just quiet, but I m sending this message to test. I m enjoying
      Message 31 of 31 , Oct 27, 2010
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        A few list users have expressed concern about the lack of list
        activity. I suspect it is just quiet, but I'm sending this message to
        test.

        I'm enjoying coordinating and co-teaching three weeks of SEI
        workshops in the NW US now. This week we have Hugh Piggott from
        Scotland, Dan Bartman from Colorado, and Jason Stone from Oregon here
        teaching a group how to build wind generators from scratch. If you're
        interested in seeing photos, see my fb page -- link below.

        Regards,

        Ian

        --

        Ian Woofenden, Renewable Energy Author, Speaker, & Consultant
        360-770-1520
        ian.woofenden@...
        http://www.facebook.com/IanWoofendenRE
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