Air core inductors, calculations

r!sc! · 25th July 2004, 06:01 PM

Hi,

I need for the x-over next air core inductors:

1mH - 14ga wire

1.5mH - 14ga wire

0.25mH - 20ga wire

I found on http://www.lalena.com/audio/calculator/inductor/
air core calculator but i don't know what is the best proportion-ratio between Coil Diameter and Coil Length.

Please, can someone help me with this calculations?

Just one hint, the inductor (finished) should be not to big in diameter.

Thanks, Boban

r!sc! · 25th July 2004, 08:48 PM

Nobody

Ron E · 25th July 2004, 09:22 PM

http://home.earthlink.net/~jimlux/hv/wheeler.htm

I am not sure where the lalena formula came from, although it appears to be a modified version of wheelers single layer formula. With the test coils I have made, the wheeler formulas are satisfactory.

Shape does not appear to be a really sensitive factor for coils. I minimized the wheeler equation for lowest DCR and found one minima at 6*a = 9*b = 10*c , if I am recalling things correctly. Rather large deviations from this shape (that had the same inductance) did not appear to change DCR much...

Some other equations specify that the inner radius of the windings should be equal to the length of the coil, ("b" in the equations below)

The equations below are copied from the page in the link above, but they can also be found in the ARRL handbook and many other places..
----------------------------------------------------------------
L (uH) = 0.8 * a^2 * n^2 / (6*a + 9*b + 10*c )

where
a = average radius of windings
b = length of the coil
c = difference between the outer and inner radii of the coil.
all dimensions in inches.

It states that it is accurate to 1% when the terms in the denominator are
about equal. This is also an equation by Wheeler. It applies as long as the
coil has a rectangular cross section.

Ron E · 25th July 2004, 09:37 PM

http://www.fnrf.science.cmu.ac.th/th...ed%20coil.html

Note that the link confirms the low sensitivity of shape, but gives you the answer you wanted.

Jay · 26th July 2004, 10:44 AM

Or you can go to http:\\www.solen.ca and check their inductors' size and dimension before plugging the numbers into the online calculator. Their dimension is computer optimized.

r!sc! · 26th July 2004, 11:30 AM

Great

. Thanks.

Boban

rabbitz · 26th July 2004, 03:10 PM

Here's a great little calculator.

http://members.optusnet.com.au/~audiosoft/inductor.exe

25th July 2004, 06:01 PM	#1
r!sc! Account Disabled Join Date: Jun 2003 Location: Serbia	Air core inductors, calculations Hi, I need for the x-over next air core inductors: 1mH - 14ga wire 1.5mH - 14ga wire 0.25mH - 20ga wire I found on http://www.lalena.com/audio/calculator/inductor/ air core calculator but i don't know what is the best proportion-ratio between Coil Diameter and Coil Length. Please, can someone help me with this calculations? Just one hint, the inductor (finished) should be not to big in diameter. Thanks, Boban

25th July 2004, 09:22 PM	#3
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	http://home.earthlink.net/~jimlux/hv/wheeler.htm I am not sure where the lalena formula came from, although it appears to be a modified version of wheelers single layer formula. With the test coils I have made, the wheeler formulas are satisfactory. Shape does not appear to be a really sensitive factor for coils. I minimized the wheeler equation for lowest DCR and found one minima at 6a = 9b = 10c , if I am recalling things correctly. Rather large deviations from this shape (that had the same inductance) did not appear to change DCR much... Some other equations specify that the inner radius of the windings should be equal to the length of the coil, ("b" in the equations below) The equations below are copied from the page in the link above, but they can also be found in the ARRL handbook and many other places.. ---------------------------------------------------------------- L (uH) = 0.8 a^2 * n^2 / (6a + 9b + 10c ) where a = average radius of windings b = length of the coil c = difference between the outer and inner radii of the coil. all dimensions in inches. It states that it is accurate to 1% when the terms in the denominator are about equal. This is also an equation by Wheeler. It applies as long as the coil has a rectangular cross section. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan* Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

25th July 2004, 09:37 PM	#4
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	http://www.fnrf.science.cmu.ac.th/th...ed%20coil.html Note that the link confirms the low sensitivity of shape, but gives you the answer you wanted. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Which, Foil Air Core or Iron Core Inductors	slhijb	Multi-Way	16	20th November 2009 03:12 AM
T-amp air core inductors - DIY	jkeny	Class D	1	23rd March 2006 05:19 AM
Core saturation and flux density calculations	machinehead	Power Supplies	8	17th January 2006 07:45 PM
Solen Air core inductors, Hammond Iron core.	gnomus	Swap Meet	0	30th July 2004 01:28 AM
Air core inductors	Jason Hubbard	Swap Meet	17	5th April 2004 11:44 AM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

25th July 2004, 08:48 PM	#2
r!sc! Account Disabled Join Date: Jun 2003 Location: Serbia	Nobody

26th July 2004, 10:44 AM	#5
Jay diyAudio Member Join Date: Feb 2003 Location: Jakarta	Or you can go to http:\\www.solen.ca and check their inductors' size and dimension before plugging the numbers into the online calculator. Their dimension is computer optimized.

26th July 2004, 11:30 AM	#6
r!sc! Account Disabled Join Date: Jun 2003 Location: Serbia	Great . Thanks. Boban

26th July 2004, 03:10 PM	#7
rabbitz diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	Here's a great little calculator. http://members.optusnet.com.au/~audiosoft/inductor.exe

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read