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Analyzing circuits from the handbooks and EFV DVDs

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  • Analyzing circuits from the handbooks and EFV DVDs

    Hi All,

    With Gary and RS I am/was analyzing in debt what is going on in the circuit of the SG starting in post #258 in this thread
    I would like to analyze some more circuits and therefore started a new thread here since these circuit discussions didn’t seem appropriate in the above mentioned thread.

    Last edited by pearldragon; 07-30-2020, 06:05 AM.

  • #2
    Windmill SG
    In EFV DVD 25 John talks about a setup where the rotor is put in motion by wind (or a water stream, or similar), rather than by attraction/repulsion of the main coil. In the text below I refer to such a setup by a “windmill SG”.

    Looking at the schematic in the attachment, I would assume that a windmill SG would yield a higher COP than a regular SG, since the rotor now does not have to be put into motion by energy drawn* from the input battery.

    But I’m struggling to understand this on a theoretical level. What I mean is this:
    If for a windmill SG, as per schematic in the attachment, I would use the same setup for the rotor/magnets and electronics as a regular SG, the power drawn from the primary battery is (amongst other things) determined by how long the transistor is conducting/on. Now assuming a windmill SG and a regular SG are running at the same RPM, the ‘on time’ would be the same for both.
    My question then is: where does the energy saving/higher COP takes place exactly in a windmill SG version?

    Is this because in a regular SG some of the electromagnetic energy in the coil will be converted to mechanical energy to attract (or push) the rotor, while in a windmill SG all of this electromagnet energy is available to create a bigger radiant spike? (That would actually mean that the savings in energy would show up more in the way that the output battery gets charged faster, rather than then input battery be drained slower. Although the latter can be true too since it receives some radiant spike too).

    *The energy used to put the rotor into motion can of course be harnessed again as mechanical energy from the wheel. Assuming that friction/air resistance losses are minimal, in theory a windmill SG would not save much in comparison to a regular SG I guess?

    Thanks in advance,

    2020-07-30 - attachment windmill SG.pdf


    • #3
      Another though I had on this:
      For a “tuned” Windmill SG, the ON-time of the transistor can be a lot shorter than with a regular SG. With a regular SG the transistor will be ON as long as the trigger coil is “triggered” by the magnets on the rotor when they are approaching (or leaving). But since the Windmill SG does not need to set the rotor in motion, the transistor only needs to be ON until the main coil is excited to the max.
      So in order to have the Windmill SG operated at its highest possible COP (and the above train of thoughts is correct), the circuitry in the trigger coil circuit has to be adjusted/modified so that the transistor is ON just long enough so that the main coil is fully excited.
      Last edited by pearldragon; 08-05-2020, 06:12 AM.


      • #4

        A wind mill trigger is not very different from a regular SSG. Just a 2nd coil that the wind turns the wheel vs a self triggered circuit. Move your regular SSG coil away from the wheel, unhook your trigger wire on your regular SSG coil then take a 2nd coil and mount it next to the wheel and hook it up like the trigger strand on the regular coil, Then spin the wheel by hand to get a feel for how a wind mill would work, adjust the distance to make it trigger like the regular trigger strand. JB seem to think that the varying speed of a wind mill as the wind was blowing was a good thing............. Lots of PPL have experimented with a 2nd trigger coil.

        JB once told Tom, Eric and I at his shop, that he wanted a coil the size of a 55gal barrel that was triggered from a wind mill with magnets, or even a areometer wind speed indicator.

        I have a small 2ft dia 12V output wind mill. A while back I had the idea that I could mount magnets to the ends of the blades, and use the power from the 12V genny output to power the SSG circuit, while the magnets on the blades triggered the SSG circuit with a 2nd coil. Just add a good size cap to the front end of the SSG to hold the power from the genny in between SSG triggers.
        Last edited by RS_; 08-05-2020, 09:44 PM.


        • #5
          Hi RS,

          At the moment I'm not planning to make a Windmill SG myself (first trying to get my regular SG performing to the max). But based on EFV DVD 25 I did not understand the advantage of a Windmill SG (or watermill SG) compared to a regular SG without changing the circuitry/triggering as I explain in my post #2 and #3.
          In other words, without bringing the power consumption of the input battery down (e.g. by changing the ON time of the transistor), one might as well built a regular SG I guess...

          Maybe you're answering this already in your post, but then I'm missing it. Unless you mean that I would see that the power consumption is different (if I would built it myself), when the trigger coil and the main coil are separate coils, with only the trigger coil being placed under the rotor/magnets.



          • #6
            It is the width of the magnet, distance between the magnets, and rotor speed that determines transistor on time in a regular SSG or a windmill triggered one. With all rotor factors the same, and the same coil power strand resistance, the power consumption is going to be about the same in ether case at the same rpm.

            This is a situation that 2 rolls of plain old 22ga wire could be used. one for the trigger, one for the power coil as a quickie solution with a home made wind rotor....
            Last edited by RS_; 08-06-2020, 11:33 AM.


            • #7
              Hi Gary, RS,

              I had a another look at the ringing part of the radiant signal and compared this with the CG signal.
              Where the radiant signals looks like a regular wave signal that’s demping out, the CG signals seems to have a second smaller wave signal imposed on the main wave signal.
              Could you explain a bit more what exactly causes this second smaller wave pattern to appear in the CG signal? See attachment.

              Thanks in advance,

              @RS in reply to post #6
              Thanks, that answers my question/confirms my assumption.

              Best regards,

              2020-09-15 - Attachment.pdf