Toroid Trafo as choke

Psychobiker · 5th March 2008, 07:19 PM

Hey,

Rooting through the storeroom today produced a toroidal 20-0-20-0 PSU, which when metered across the mains inputs (115-0-115-0 wired for 230V), yields 7.2H.

Anyone else done similar, and if so, did you just insulate the original taps?

L

kevinkr · 5th March 2008, 07:28 PM

Toroids have very limited tolerance for dc on their windings, likely if you use it as a choke the core will saturate and you will be left with just the winding dc resistance. Not recommended.

Psychobiker · 5th March 2008, 07:59 PM

<200mA limited ? No harm giving it a shot and seeing what happens, have access to non-toroid as well, so just a matter of experimentation

woody · 5th March 2008, 08:42 PM

I have tested a transformer as a choke and a toriod autoformer
as a choke in a choke input power supply. I Iloaded them to ~80% of there ac current rating with darn good results.
I think my results were about 5% different than calculated using
Duncan's power suply designer. Now this may not work in all cases but in the 2 cases I tried it sure did.

Psychobiker · 5th March 2008, 08:45 PM

Ta! Not massive current here, so I think we're well within our reach, it's a 50VA trafo, so...looks to be okay

5th March 2008, 07:19 PM	#1
Psychobiker diyAudio Member Join Date: Jul 2005 Location: Montréal QC	Toroid Trafo as choke Hey, Rooting through the storeroom today produced a toroidal 20-0-20-0 PSU, which when metered across the mains inputs (115-0-115-0 wired for 230V), yields 7.2H. Anyone else done similar, and if so, did you just insulate the original taps? L

5th March 2008, 07:28 PM	#2
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Toroids have very limited tolerance for dc on their windings, likely if you use it as a choke the core will saturate and you will be left with just the winding dc resistance. Not recommended. __________________ www.kta-hifi.net

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5th March 2008, 07:59 PM	#3
Psychobiker diyAudio Member Join Date: Jul 2005 Location: Montréal QC	<200mA limited ? No harm giving it a shot and seeing what happens, have access to non-toroid as well, so just a matter of experimentation

5th March 2008, 08:42 PM	#4
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	I have tested a transformer as a choke and a toriod autoformer as a choke in a choke input power supply. I Iloaded them to ~80% of there ac current rating with darn good results. I think my results were about 5% different than calculated using Duncan's power suply designer. Now this may not work in all cases but in the 2 cases I tried it sure did.

5th March 2008, 08:45 PM	#5
Psychobiker diyAudio Member Join Date: Jul 2005 Location: Montréal QC	Ta! Not massive current here, so I think we're well within our reach, it's a 50VA trafo, so...looks to be okay

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