pi filter variations

CarlyBoy · 5th December 2009, 04:09 PM

'Hope the following image is legible...

A is the typical choke pi filter. B has the choke on the ground side. C has both. I can't model either B or C in PSUD (as far as I can tell anyway). So a few questions:

1. Is there any disadvantage to B? It seems like a good option for situation when choke doesn't have a high enough voltage rating.

2. Does C have any advantage over A or B? Or would two such chokes, say of equal inductance, be equivalent to having one choke (as in either A or B) of twice the inductance?

Thanks for any help.

zigzagflux · 5th December 2009, 07:36 PM

There is not really any disadvantage to B, in fact it is chosen for the very reason you cite. Of course, circuit common must come off the negative end of the second filter cap.

C might be a tad bit advantageous in reducing common mode noise, but power chokes are somewhat limited in their ability to block RF. C is what I use in my preamp.

For the purposes of PSUD, there is no difference between A and B, and to model C you add the inductances of each individual choke, modeling it exactly the same as A and B.

nicoch58 · 5th December 2009, 07:44 PM

274A Datasheet. Emission Labs.

BHD · 6th December 2009, 12:42 AM

One Electron also makes dual wound chokes and I have a few of them. I never thought to use them like the above Emission Labs diagram. Interesting.

Kashmire · 6th December 2009, 04:42 AM

Quote:

2. Does C have any advantage over A or B? Or would two such chokes ...

As drawn and explained in the original post, separate (two) chokes for "C" would be the same as doubling A or B. There would be no advantage to C.

However, if C used a single core with dual windings, it would act as a common-mode choke as illustrated by nicoch46.

CarlyBoy · 6th December 2009, 12:52 PM

I am liking the dual wound choke idea. Would the following full-wave bridge arrangement be correct with a single core/dual wound choke like the Lundahl or One Electron mentioned?

nicoch58 · 6th December 2009, 02:02 PM

more info

Kashmire · 6th December 2009, 03:24 PM

Yes, that is the correct use of the common-mode choke.

5th December 2009, 04:09 PM	#1
CarlyBoy diyAudio Member Join Date: Aug 2006	pi filter variations 'Hope the following image is legible... A is the typical choke pi filter. B has the choke on the ground side. C has both. I can't model either B or C in PSUD (as far as I can tell anyway). So a few questions: 1. Is there any disadvantage to B? It seems like a good option for situation when choke doesn't have a high enough voltage rating. 2. Does C have any advantage over A or B? Or would two such chokes, say of equal inductance, be equivalent to having one choke (as in either A or B) of twice the inductance? Thanks for any help.

6th December 2009, 12:42 AM	#4
BHD diyAudio Member Join Date: Jun 2004 Location: Brooklyn Park, MN	One Electron also makes dual wound chokes and I have a few of them. I never thought to use them like the above Emission Labs diagram. Interesting. __________________ My religion is the golden rule. The only time it's forsaken me is when I've forsaken it first.

6th December 2009, 12:52 PM	#6
CarlyBoy diyAudio Member Join Date: Aug 2006	So this bridge arrangement ok? I am liking the dual wound choke idea. Would the following full-wave bridge arrangement be correct with a single core/dual wound choke like the Lundahl or One Electron mentioned?

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
Temp Variations CH to CH	Zero Cool	Everything Else	0	4th February 2007 01:25 PM
Q: The Zen Variations Book	Michael Rothacher	Pass Labs	5	5th March 2004 05:14 PM
Zen Variations 5	Nelson Pass	Pass Labs	66	5th August 2003 04:57 PM
Zen Variations part 4	Nelson Pass	Pass Labs	34	29th August 2002 11:23 PM
Zen & Zen Variations-Part.2	billy	Pass Labs	1	7th August 2002 06:24 PM

5th December 2009, 07:36 PM	#2
zigzagflux diyAudio Member Join Date: Oct 2006	There is not really any disadvantage to B, in fact it is chosen for the very reason you cite. Of course, circuit common must come off the negative end of the second filter cap. C might be a tad bit advantageous in reducing common mode noise, but power chokes are somewhat limited in their ability to block RF. C is what I use in my preamp. For the purposes of PSUD, there is no difference between A and B, and to model C you add the inductances of each individual choke, modeling it exactly the same as A and B.

6th December 2009, 03:24 PM	#8
Kashmire diyAudio Member Join Date: Dec 2003 Location: Midwest	Yes, that is the correct use of the common-mode choke.

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