Electronics > Projects, Designs, and Technical Stuff
How do "Goofy-Wound" Inductors Work?
boB:
--- Quote from: ejeffrey on January 11, 2019, 05:33:45 am ---
Sure, it is useful if you want to make a high power 50 ohm load or other RF power resistor. But that's about it.
--- End quote ---
Sounds pretty useful to me !
Zero999:
SuzyC,
I'm sure you now realise that the purpose of this winding is to be non-inductive, so the title of the thread is contradictory.
Another way to think of this is a transformer with two primary windings connected out of phase. The supply feeding the transformer will just see the DC resistance of the windings connected in parallel. The magnetising fluxes will cancel, so there will be no inductance and the transformer will not work. A large current will flow, causing the fuse or circuit breaker to open.
coppercone2:
--- Quote from: ejeffrey on January 11, 2019, 05:33:45 am ---
--- Quote from: SuzyC on January 11, 2019, 01:59:19 am ---T3sl4co1l, thanks again for soothing my damaged brain.
But since this type of wiring cancels the magnetic field, is energy lost in the process due to flux creation/cancellation?
--- End quote ---
No, flux cancellation doesn't cause energy loss. Its not like the flux is created and they destroyed, the current path just creates very little flux. Energy will be lost due to the wire resistance of course, and if there is imperfect cancellation then you can get radiation.
--- Quote ---Isn't cancellation of local fields means no radiating field a very useful property for transmitting energy in a very sensitive or high-power RF circuit or even in a power transmission line?
--- End quote ---
Sure, it is useful if you want to make a high power 50 ohm load or other RF power resistor. But that's about it.
--- End quote ---
I think she is asking about a transient field analysis diagram of such a system.
MrAl:
--- Quote from: SuzyC on January 10, 2019, 11:29:22 pm ---We have all seen a lot of info about different inductors, but what about "Goofy-Wound" inductors?
Suppose we have a toroidial core and I wind half the total winding in one direction and the remainder in the opposite direction(changing from CW winding to CCW).
What is the inductance and behavior of such a hybrid?
Would such an inductor have a practical application?
--- End quote ---
The short answer is you will get partial cancelation of the total inductance. You never get total cancelation though because the two windings always occupy different locations in space, and different locations means that the fields do not interact completely.
There are calculations you can do on simple structures but as the structure gets more complicated the solution gets more difficult because it involves mutual inductance which involves integration in sometimes several directions.
To keep it simple though, when you have two wires each with current flow the mutual inductance depends on the orientation of the wires and distance from each other, and because there are so many different shapes and ways to separate them, the shape is most likely a function and the distance is also a function, so integrating gets a little complicated real fast. Some good books resort to tables for commonly wound structures such as cylindrical coils and coils with triangular and rectangular cross sections, and cross sections that have multiple sides (like a hex for a six sided cross section). The formulas often also neglect certain aspects such as wire diameter but sometimes include that too.
If not anything else, it's a really interesting subject area. If you are into calculus, pick up a book.
When i first saw the title of this thread i thought it would be about a randomly wound coil which is sometimes used.
ebastler:
--- Quote from: SuzyC on January 11, 2019, 12:20:13 am ---Why so little mention or interest about the use and characteristics of this kind of inductor?
--- End quote ---
Because an "inductor" wound for minimum inductance is pointless? :P
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