Using common mode chokes in filament supply.

G · 9th December 2002, 03:01 PM

How do you apply a common mode choke in a filament supply? Do you put one in series with each 6.3 volt filament or in parrallel with all of them. Also what size do you use? My guess is that you would put them in series with each filament. But that is just a guess.

G

Bas Horneman · 9th December 2002, 03:27 PM

Hi..a common mode filter..as I see it is just a choke in the positive AND the negative voltage rail... With the difference that they are connected to the same core.

I use a mains filter ..commonly used before the transformer in ..say a cd player.. but instead I use it in the filament of my driver tube...

So each "inductor" will be in series on each rail..but the two inductors will be "parallel"..

Hope this helps..

Regards,
Bas

Bas Horneman · 9th December 2002, 03:30 PM

.

G · 9th December 2002, 03:37 PM

Thanks Bas. Is there a certain value that you prefer to use for filament supplies? Also, would putting a capacitor across the line at each filament in addition to the CMC would help also. Thanks for the info.

G

Bas Horneman · 9th December 2002, 03:42 PM

Hi G,

Nope I use any value really. And yes, putting a cap a cap across the filament would indeed help. I also use this..

But better still would be to use 2 caps...one on each leg of the filament...and each one to ground...this would be the "second" part of your filter..

So that you would have a LC filter on each leg..

Cheers,
Bas

Brett · 9th December 2002, 03:50 PM

Thanks for that Bas. I was looking for an image to post with an explanation earlier tonight before I went out, but it looks like you beat me to it.

Cheers

Bas Horneman · 9th December 2002, 03:56 PM

Yeah, the image is a little confusing though if you look at the arrows.. :-)

R U busy building a tube amp? Or tweaking an existing one?

Bas Horneman · 9th December 2002, 03:58 PM

O.. hi Brett..

I thought G posted that.. :-)

By the way..do you think it is worthwile doing this..on an IDH tube..I did it on my 6n1p driver..but I am to lazy to undo it to check if it makes a difference..

Cheers,
Bas

Brett · 9th December 2002, 04:10 PM

Quote:

Originally posted by G
Is there a certain value that you prefer to use for filament supplies?

G,

I buy mine from an industrial parts supplier, and get the biggest value CM choke I can, usually in the order of a few mH or more depending upon the current rating. Larger 100mH are about $5 and I'm going to add some of these to my MC phono stage when it's apart next.

As noted elsewhere, a CM choke won't reduce hum, unless it's a couple of orders of magnitude larger, and probably more expensive too.

9th December 2002, 03:01 PM	#1
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	Using common mode chokes in filament supply. How do you apply a common mode choke in a filament supply? Do you put one in series with each 6.3 volt filament or in parrallel with all of them. Also what size do you use? My guess is that you would put them in series with each filament. But that is just a guess. G __________________ Gavin

9th December 2002, 03:37 PM	#4
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	Thanks Bas. Is there a certain value that you prefer to use for filament supplies? Also, would putting a capacitor across the line at each filament in addition to the CMC would help also. Thanks for the info. G __________________ Gavin

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
common-mode chokes	jarthel	Tubes / Valves	6	11th February 2008 04:31 PM
Common-mode EI PS Chokes	rdf	Tubes / Valves	14	17th June 2007 09:36 AM
Common Mode Chokes for Heater Supplies	ppereira	Tubes / Valves	7	29th January 2006 02:45 PM
Source for common mode chokes	abj1	Tubes / Valves	7	24th June 2005 07:31 AM
Common mode chokes	Dr.H	Digital Source	1	24th July 2002 05:47 PM

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

9th December 2002, 03:27 PM	#2
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	Hi..a common mode filter..as I see it is just a choke in the positive AND the negative voltage rail... With the difference that they are connected to the same core. I use a mains filter ..commonly used before the transformer in ..say a cd player.. but instead I use it in the filament of my driver tube... So each "inductor" will be in series on each rail..but the two inductors will be "parallel".. Hope this helps.. Regards, Bas

9th December 2002, 03:42 PM	#5
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	Hi G, Nope I use any value really. And yes, putting a cap a cap across the filament would indeed help. I also use this.. But better still would be to use 2 caps...one on each leg of the filament...and each one to ground...this would be the "second" part of your filter.. So that you would have a LC filter on each leg.. Cheers, Bas

9th December 2002, 03:50 PM	#6
Brett diyAudio Member Join Date: Jan 2002	Thanks for that Bas. I was looking for an image to post with an explanation earlier tonight before I went out, but it looks like you beat me to it. Cheers

9th December 2002, 03:56 PM	#7
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	Yeah, the image is a little confusing though if you look at the arrows.. :-) R U busy building a tube amp? Or tweaking an existing one?

9th December 2002, 03:58 PM	#8
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	O.. hi Brett.. I thought G posted that.. :-) By the way..do you think it is worthwile doing this..on an IDH tube..I did it on my 6n1p driver..but I am to lazy to undo it to check if it makes a difference.. Cheers, Bas

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