Theoretical Question about transformers

Discussion in 'Off-Topic' started by germeten, Aug 14, 2015.

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  1. germeten

    Thread Starter New Member

    Apr 18, 2014
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    Hi, this may sound pretty basic, but I've read books all the way up to RF communications so I'm not ignorant
    about conventional theory, but I do like to revisit basic concepts from time to time to see if anything is being
    missed.

    So the notion is that a transformer can step up or down current or voltage based upon turns ratio between
    primary & secondary, and of course we know this is true, however:

    Radio theory presumes (and devices prove) that magnetic fields radiate off into space for quite some distance.
    We can consider magnetic fields as individual closed loops that excite electron movement in the wires they cross.

    I prefer to use RF coil in this example vs. a closed-loop iron core transformer.

    Imagine a hollow plastic core tube upon which a coil of wire is wound, and through which RF energy will be pulsed.
    Imagine also, a secondary winding of same wire thickness and number of turns. Then imagine a third, fourth and
    fifth... winding, similar to the secondary, all layered over the primary. Imagine then all of these secondary coils,
    each of equal number of turns as the primary, wired in PARALLEL, such that when the primary winding is energized,
    all the field lines cross ALL of the secondary coil(s) windings.

    Now in terms of a single secondary, we would assume energy in primary = energy out secondary (with minor losses),
    however with multiple secondaries in parallel, I'd like to know why the expanding and collapsing field lines wouldn't
    be additive, i.e. the energy manifested in the first secondary would appear in equal magnitude in all secondaries.
    In other words, the energy input into primary 'z would equate to 'z times (N), where (N) is the number of secondary
    coils, again assuming they are of roughly same dimensions, turns, wire thickness, and concentrically wound, so that
    primary field lines cut all secondary coil(s) windings. Since the primary and secondary windings of equal turns, 'see'
    the same voltage, why wouldn't current be amplifed by and within the sheer greater surface area of the secondaries?
    I'm assuming that field lines don't weaken just for cutting more copper.
     
  2. #12

    Expert

    Nov 30, 2010
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    The voltages in all the unloaded secondaries would be equal but the limitation of power in = power out means the current available will be used up. You can load one secondary and use up the energy. You can load all secondaries equally and use up the power in 5 equal amounts. You can load the secondaries unequally and use up the power in unequal amounts. You can not use up more power than you provide.
     
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  3. crutschow

    Expert

    Mar 14, 2008
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    Each secondary that carries current and draws power generates a magnetic field which opposes the magnetic field from the primary.
    Thus the field lines aren't weakened by just cutting more copper but they are weakened (reduced) by any current in the secondary. The primary must then increase its current to maintain the magnetic flux, which requires more primary energy. That's how the primary energy is transferred to the secondary.
     
  4. BR-549

    Well-Known Member

    Sep 22, 2013
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    Because the amount of power that a secondary absorbs from the primary flux, is dependent on the load of that secondary.

    This power is limited to the power of the primary.

    So the power available to a secondary is equal to the power of the primary, minus the power of the other secondaries.
     
  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    No, they weaken because Faraday's Law of Induction has a minus sign in it, but Ampere's Law does not.

    ak
     
  6. germeten

    Thread Starter New Member

    Apr 18, 2014
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    OK, I take all your comments under advisement, but I'm still not convinced this weakening would occur under all circimstances. What if the secondaries weren't in close proximity to one another? A radio transmitter antenna emits signal in all directions. The receiver in one township doesn't steal signal from another. Note I'm talking in terms of signal, or field lines crossing copper, not transformer law that says power in = power out. A river can power any number of water wheels. The force of the river is not diminished.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Not true. Most of the useful energy is obtained by the fall of the water. If the first wheel used all the fall from the mountain to the prairie to the ocean then there is nothing left for any other wheel. If you are just using the horizontal flow you could keep adding wheels until their collective back force equals the flow force and essentially you get a multi-piece dam and no flow is possible.

    Again, energy out <= energy in. Always.
     
  8. Jampo

    New Member

    Aug 6, 2015
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    Whether you like it or not, you are talking about transformers no matter which way you wired them. Multiple centre taps at that whether they are on top of each other or next to each other. Call it RF Energy or AF Energy, it is still just energy operating at Radio or Audio Frequency which is the only difference. Loosely wound secondaries will only destroy the electro-magnetic coupling. Rivers flow from the mountains to the sea because of the difference in the potential energy which is determined by the height of one point above the other. Kinetic energy is imparted by some force on a body. Friction is always there as seen in crutshow's mail. Again the form it takes does not matter. Nice try for perpetual motion, but no cigar.
     
  9. BR-549

    Well-Known Member

    Sep 22, 2013
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    Once a field line is absorbed in a coil, it is gone and is converted to current, and not available to cut other coils.

    A coil makes current out of field, and makes field out of current.
     
  10. germeten

    Thread Starter New Member

    Apr 18, 2014
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    ErnieM: You said:

    "Not true. Most of the useful energy is obtained by the fall of the water. If the first wheel used all the fall from the mountain to the prairie to the ocean then there is nothing left for any other wheel. If you are just using the horizontal flow you could keep adding wheels until their collective back force equals the flow force and essentially you get a multi-piece dam and no flow is possible.

    Again, energy out <= energy in. Always."

    Yes, the energy is obtained by fall of water, but in electricity, still corresponds to pressure, volume, flow (voltage, current). Of course is also subject to good engineering, no one wants to stop the wheel or block flow, but just exploit the movement to do work. Even a slow moving river has a lot of force if the paddles have sufficient surface area. Your dam analogy (pardon the pun) is good, because it begs the question whether more power might be generated with more wheels rather than an imposing blockage to try and get all one's energy all at once.

    Jampo: You said:

    "Whether you like it or not, you are talking about transformers no matter which way you wired them. Multiple centre taps at that whether they are on top of each other or next to each other. Call it RF Energy or AF Energy, it is still just energy operating at Radio or Audio Frequency which is the only difference. Loosely wound secondaries will only destroy the electro-magnetic coupling. Rivers flow from the mountains to the sea because of the difference in the potential energy which is determined by the height of one point above the other. Kinetic energy is imparted by some force on a body. Friction is always there as seen in crutshow's mail. Again the form it takes does not matter. Nice try for perpetual motion, but no cigar."

    Transformers are transducers converting one form of energy into another. In terms of secondaries I understand they can be placed anywhere with respect to the transmitter coil, even quite remote. Certainly power falls off with distance, but I don't see distant coils stealing from one another. Actually the precipitation cycle is a good example of "perpetual motion." Granted it requires solar input (which is free); the error in your thought, if I might say so, is that you are presuming electromagnetic devices are closed systems.

    BR-549: You said

    "Once a field line is absorbed in a coil, it is gone and is converted to current, and not available to cut other coils.
    A coil makes current out of field, and makes field out of current."

    Now that is getting to the heart of it, and yet I don't think it's rigorously true, because we know that EM waves do continue on to the next receiver, and the next, etc. A secondary coil "out there" doesn't stop field lines from reaching even more distant receivers. A secondary/receiving coil isn't a black-hole/sink for all EM that reaches it, and I don't know that current flow kills the field lines.

    Someone sent me a promotion for a Tesla device report which I purchased. It details the winding of a coil that's placed upon an induction cooker. The output is double the input, measured by load and meters. I did some research on induction cookers, found they operate at RF, 25kHz-100kHz, contain a resonant tank that self adjusts with the load, which is important. I will be replicating this experiment. As far as other over-unity devices, there have been some successes. I've been studying such patents for over 20 years, some of which I do understand, though never seem to make it into commerce. There are also ookles of experimenters on Youtube and other forums, posting their work.
     
  11. #12

    Expert

    Nov 30, 2010
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    That's what I thought you were after.
     
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  12. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    I see a lot of "rough intuition" in this thread.

    Intuition is great, but it usually lacks detail. For this comparison between water, fields, and RF transmission we need a more exacting experiment.

    I do like the water analogy, and the fact is that if you block all the water then you have no more water flow and so no more energy. For the RF transmission it looks like any number of antennas get power, but that's not true either. If we could have one antenna right in front of the other in the line of transmission, the second antenna would see a reduced amplitude just like the water wheels. If we had an array of antennas in the shape of a sphere all around the transmitter then little or no energy would be left to transmit to your home TV set. So the power absorbed by all antenna summed will be equal to or less than any power transmitted, and it's almost always less.

    It is also interesting that even one water wheel in a river slows the total flow by at least some small amount. For falling water the force on the first wheel encountered will be greatest unless the distance between wheels is adjusted to keep the forces equal, but that means the second wheel downstream can not get the force of the full height it must get the force from the height of the first wheel. So although the second wheel gets the same force as the first, it gets less than it could have gotten if it had been the only wheel installed because it only has the force from half the height of the waterfall instead of the force from the full height.
     
    Last edited: Aug 18, 2015
  13. BR-549

    Well-Known Member

    Sep 22, 2013
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    There is a huge difference between a static(connected) line and an emitted line.

    A connected line is complete, circular and rotating. An emitted line in incomplete, partial, and even though it is traveling, it is not rotating.

    Magnetic flux converts to current, current converts to flux. There's no killing involved.

    You can not get something for nothing. Nature is a very strict bean counter.
     
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  14. Wendy

    Moderator

    Mar 24, 2008
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    cmartinez, JoeJester and Jampo like this.
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