Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

Output Inductors
Output Inductors
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
Thread Tools Search this Thread
Old 4th February 2008, 06:18 AM   #1
jkeny is offline jkeny  Ireland
Join Date: Feb 2007
Location: Dublin
Default Output Inductors

Can anybody say if the apparent closeness of these output inductors could cause problems - mutual inductance?
Attached Images
File Type: jpg sa-xr55 compressed.jpg (76.8 KB, 390 views)
  Reply With Quote
Old 4th February 2008, 03:49 PM   #2
y8s is offline y8s  United States
diyAudio Member
y8s's Avatar
Join Date: May 2006
Send a message via AIM to y8s Send a message via MSN to y8s Send a message via Yahoo to y8s
toroidal inductors tend to have a pretty tight leash on leakage flux. if you do the 'right hand rule' on them, you'll see that the field (at least in theory) cancels itself out.

so the effect is probably minor.
  Reply With Quote
Old 5th February 2008, 06:55 AM   #3
Ouroboros is offline Ouroboros  England
diyAudio Member
Ouroboros's Avatar
Join Date: Dec 2003
Location: Nottingham UK
Even if the flux was 100% contained within the toroid, there would still be a 'virtual' single turn air-cored coil when you wind a toroid as a single winding. You can wind half the toroid and then take the wire diametrically across to the other side and finish winding the other half. (As seen in the better type of inductors on some SMPSUs). This cancels out most of the 'virtual single turn' effect.
(Bruno Putzeys for example stresses this point quite often. I know he frowns upon toroids that are not co-planar to the pcb).

So basically, in your photo, from the mutual coupling point of view, you have a number of single-turn air-cored inductors in line. There will be some coupling but I doubt if it will cause any problem.
  Reply With Quote
Old 5th February 2008, 07:30 AM   #4
Eva is offline Eva  Spain
diyAudio Member
Eva's Avatar
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Winding toroids in two opposed "runs" as encouraged by some authors does *not* solve the parasitistic turn problem at all. It just produces an eight-shaped dipole. Near field improvement on leakage flux is marginal, except exactly on the perpendicular axis where flux cancellation arises. Furthermore, far field leakage flux in toroids is negligible so no improvement is easily measurable either.

Don't worry that much about these toroids.
I use to feel like the small child in The Emperor's New Clothes tale
  Reply With Quote
Old 8th February 2008, 11:31 AM   #5
ranga is offline ranga  Romania
diyAudio Member
Join Date: Dec 2007
Originally posted by Ouroboros
Even if the flux was 100% contained within the toroid, there would still be a 'virtual' single turn air-cored coil when you wind a toroid as a single winding.
Would this configuration solve the issue?
Click the image to open in full size.
if you compute the inductance as 2 series inductors and wind them at 180 degrees they will cancel each other (the fields from each single turn air inductor). Am i right ?

edit: Sorry about my MsPaint skills !!
  Reply With Quote


Output InductorsHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Shielded or Toroidal Inductors for Class D output filter speakerguy79 Class D 24 10th February 2009 10:33 PM
Class T Output Inductors : Litz or Solid Core? Peteruk Class D 2 8th April 2007 01:03 AM
Dual differential mode inductors in a bridged output lowpass filter BWRX Class D 3 17th November 2005 03:39 PM
SI with AMP3 toroid output inductors BWRX Class D 14 11th July 2005 01:44 PM

New To Site? Need Help?

All times are GMT. The time now is 04:14 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio