Tweet
@Dllbare,
Always they are limitations. Limitations in the longer coils has to do with magnetic flux strenth. Longer coils will perform poorly in open air inductor configuration. (one end to magnet the other open air).
........................
For our relative small setups, and in case you want to achieve high inductunces - i do not meant your 130 turns of wire - but for some 3-4000 turns it is always advantageous to have a longer coil so to minimize wire distancing from core -thus better efficiency at passive power generation. (for a given ohmage wire - Core losses are another issue)
....................
Have in mind that the coil's power generation ability is "formulated" by the magnetic field which is intercepted by coil's turns at the surface of iron and drops at square of distance while its core flux goes "un-exploited".
Also, have in mind that crosssection of a circle grows exponentialy to the radius while surface proportionally to length.
Bottom line, if you have a closed loop magnetic flux - that means - flux weakens only a little by distance from your magnets - you can better increase performance of a coil by elongating it, thus increasing surface and reducing layer thickness (distance from core) rather than packing too many layers on a short core or even widen the core.
edit: When widen the core, the magnetic field (if flux density steady) epxands also and projects further. But suitability and core losses matters arise
To give you an roughly idea, perhaps erroneous one in terms of accuracy, in my setups that i am after inductunce with the minimum wire by having a coil 90mm long filled with 50ohms 24awg (1kgr+ of wire!) is almost 20-30% better (my guesswork here judging by output) by having same wire in (45mm core)
Am i understood? I think yes.
Regards,
Baroutologos
ps: we are comparing same core diameters
ps2: It works either way. As electromagnet or in passive generation mode
ps3: Its an issue only for lots of wire
Always they are limitations. Limitations in the longer coils has to do with magnetic flux strenth. Longer coils will perform poorly in open air inductor configuration. (one end to magnet the other open air).
........................
For our relative small setups, and in case you want to achieve high inductunces - i do not meant your 130 turns of wire - but for some 3-4000 turns it is always advantageous to have a longer coil so to minimize wire distancing from core -thus better efficiency at passive power generation. (for a given ohmage wire - Core losses are another issue)
....................
Have in mind that the coil's power generation ability is "formulated" by the magnetic field which is intercepted by coil's turns at the surface of iron and drops at square of distance while its core flux goes "un-exploited".
Also, have in mind that crosssection of a circle grows exponentialy to the radius while surface proportionally to length.
Bottom line, if you have a closed loop magnetic flux - that means - flux weakens only a little by distance from your magnets - you can better increase performance of a coil by elongating it, thus increasing surface and reducing layer thickness (distance from core) rather than packing too many layers on a short core or even widen the core.
edit: When widen the core, the magnetic field (if flux density steady) epxands also and projects further. But suitability and core losses matters arise
To give you an roughly idea, perhaps erroneous one in terms of accuracy, in my setups that i am after inductunce with the minimum wire by having a coil 90mm long filled with 50ohms 24awg (1kgr+ of wire!) is almost 20-30% better (my guesswork here judging by output) by having same wire in (45mm core)
Am i understood? I think yes.
Regards,
Baroutologos
ps: we are comparing same core diameters
ps2: It works either way. As electromagnet or in passive generation mode
ps3: Its an issue only for lots of wire
Comment