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Science Forum Index » Physics - Electromagnetic Forum » coil calculation formula...
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| Camilo... |
 Posted: Mon Jun 16, 2008 1:17 pm |
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hi everybody!I need to know if exists any formula or software that
lets you calculate the number of turns of an existent coil knowing the
cross section and lenght of its core, wire diameter and its DC
resistance? ( DC resistance is a result of wire lenght so I think with
DC resistance value you'll finally get wire lenght and )
PD: I don know coil's inductance just said data |
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| Camilo... |
| Posted: Mon Jun 16, 2008 1:21 pm |
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| PD2= It's a multilayer coil |
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| Benj... |
| Posted: Mon Jun 16, 2008 6:56 pm |
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Camilo wrote:
Quote: hi everybody!I need to know if exists any formula or software that
lets you calculate the number of turns of an existent coil knowing the
cross section and lenght of its core, wire diameter and its DC
resistance? ( DC resistance is a result of wire lenght so I think with
DC resistance value you'll finally get wire lenght and )
PD: I don know coil's inductance just said data
Yes, such a formula and software exists. I wrote it. I don't
distribute it. If you have one case, give me the parameters: wire
gauge, insulation type (thickness), winding length, winding depth and
I'll post the results. If you have DC resistance I can use that to
find wire length and then number of turns etc. so you then wouldn't
need the winding depth. The software also estimates the inductance so
you could compare to the measured inductance of your coil if you get
around to measuring it. By the way, this calculator is ONLY for air
core coils! I have nothing for iron or ferrite core coils. |
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| Benj... |
| Posted: Wed Jun 18, 2008 11:48 am |
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On Jun 18, 4:47 pm, Moritz Winkler <moritz.wink... at (no spam) uni-duesseldorf.de>
wrote:
Quote: I have question too. Is it possile with your software or formula to
determin if there is an homogenous magnetic field left if i elevate the
distance between to helmholtz coils. And if there is a field left how
big it is an how strong the magnetic fiels is?
The coils i use are 14 cm diameter helmholtz coils operated a max. 1,6 A
an 65 V. They have each 755 turns. The normal distance is 7 cm between
them. But at the experment i need a microscope an only can use them in a
distance of 12 cm.
Could you tell me if there is a homogenic magnetic field left an how
strong, big it is?
I don't have a clue how to calculate something like that because i'm not
physicist, i'm a chemist.
Perhaps you can give me a hint.
many thanks from germany
Moritz
No, my software is for a different purpose. Mine is to find the
electrical characteristics of air-core coils. You put in the wire and
the size of the core and winding depth and it comes up with
resistance, inductance, weight, heating, current for standard
temperature rise and the like.
I wish I could help you, but what you need is the Helmholtz coil
calculator which IS available somewhere on the internet. I've seen it
and used it, but I seem to have misplaced the URL. Maybe someone else
here remembers it.
The way it works is you plug in a certain size volume in which you
want a magnetic field of a certain size that is uniform to some given
percentage over that volume and the software barfs out the coils you
need. Generally speaking if you need a larger volume or a more uniform
field you need larger coils. Helmholtz coils do provide quite nice
uniformity over a reasonable amount of the space between them unless
you require extremely precise uniformity. If you need a high magnetic
field you may need to wind the coils with small diameter (insulated)
copper tubing and run water through it to dissipate the heat generated
by the high currents needed. If you need very high fields you'll need
a magnet setup with an iron core (NMR style technology). Super high
fields would require superconducting magnets.
The answer to your problem should be available with a decent internet
search.
Good Luck! |
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| Moritz Winkler... |
| Posted: Wed Jun 18, 2008 3:47 pm |
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Benj schrieb:
Quote: Yes, such a formula and software exists. I wrote it. I don't
distribute it. If you have one case, give me the parameters: wire
gauge, insulation type (thickness), winding length, winding depth and
I'll post the results. If you have DC resistance I can use that to
find wire length and then number of turns etc. so you then wouldn't
need the winding depth. The software also estimates the inductance so
you could compare to the measured inductance of your coil if you get
around to measuring it. By the way, this calculator is ONLY for air
core coils! I have nothing for iron or ferrite core coils.
I have question too. Is it possile with your software or formula to
determin if there is an homogenous magnetic field left if i elevate the
distance between to helmholtz coils. And if there is a field left how
big it is an how strong the magnetic fiels is?
The coils i use are 14 cm diameter helmholtz coils operated a max. 1,6 A
an 65 V. They have each 755 turns. The normal distance is 7 cm between
them. But at the experment i need a microscope an only can use them in a
distance of 12 cm.
Could you tell me if there is a homogenic magnetic field left an how
strong, big it is?
I don't have a clue how to calculate something like that because i'm not
physicist, i'm a chemist.
Perhaps you can give me a hint.
many thanks from germany
Moritz |
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| Camilo... |
| Posted: Wed Jun 18, 2008 6:54 pm |
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pal, I took the trouble to do equations on this matter, and as I don
´t need that they must be accurate, the resulting equations are good
for my need, so, anyway thanks for your help!! |
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| Moritz Winkler... |
| Posted: Thu Jun 19, 2008 1:32 am |
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Guest
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Quote:
The answer to your problem should be available with a decent internet
search.
Thanks for the quick response, i will search for it.
Moritz |
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| Benj... |
| Posted: Thu Jun 19, 2008 6:11 am |
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On Jun 19, 12:54 am, Camilo <camilo... at (no spam) 100cia.zzn.com> wrote:
Quote: pal, I took the trouble to do equations on this matter, and as I don
´t need that they must be accurate, the resulting equations are good
for my need, so, anyway thanks for your help!!
The equations you need are not that hard to figure out if you don't
need a lot of accuracy. The big problem tends to be estimating the
wasted space in winding and the problem of "embedding" which means
that the row above fits into the grooves between wires on the row
below. In the end you just have to adjust for this with a "winding
factor". Often embedding is compensated by the less than perfect fit
between adjacent turns of a layer. So the simplest approach of a
perfectly stacked winding actually can give a reasonably decent
answer! |
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