Where to actually *get* magnetics for SMPS?

jwb · 20th April 2003, 11:37 PM

There are a lot of manufacturers for transformers, cores, and so forth, but you can't just call up Coiltronics and order five transformers. All the manufacturers have complicated sales channels and huge minimum orders.

So where are you getting magnetics for your switching power supplies? I need to build two 30V, 4A supplies for a PWM amplifier.

SkinnyBoy · 21st April 2003, 04:02 AM

The cores from computer powersupply transformers..

jwb · 21st April 2003, 05:41 AM

I just broke open the power supply from my useless DEC Multia. It has a mystery transformer, but who can tell the specs? Googling for the part number yields nothing.

Maybe I should try something made in this century.

SkinnyBoy · 21st April 2003, 06:22 AM

wind your own...

Taligent · 21st April 2003, 06:59 AM

For a power supply, characterizing unknown magnetics shouldn't be out of reach. Iron powder or ferrite can be distinguished by winding a few turns and measuring the inductance. SpeakerWorkshop can do an adequate job of measuring inductance (as well as for characterizing drivers, go figure...

). Al can be determined from this, and then narrowing down the range of possible material types should be enough to make it worth trying out the magnetic for the application.

For characterizing magnetics...
Ferrite and iron powder info
Transformers and ferrites
Assessing unknown ferrite toroids

Assuming the unknown magnetic is from a power supply, it is most likely ferrite, and the power handling can be estimated from the physical size of the ferrite. Try cross-referencing the size of the ferrite bits (EE, toroid?) against Ferroxcube or Amidon.

Recycling ferrites from various switching power supplies has been the only source I've needed for magnetics thus far...computer power supplies really are quite useful as a source, considering that 250w power supplies are now out of favor due to the recent AMD/Intel practice of approving power supplies.

Of course, DIY recycling notions aside, there are several places to order magnetics with non-corporate purchasing powers. The amateur radio community has been the trailblazer for this and other electronics parts for quite a while...

Bytemark
Palomar Engineers
Dan's Small Parts - not as much in the way of magnetics, but fun to look through all the same

HTH,
Nikhil

20th April 2003, 11:37 PM	#1
jwb diyAudio Member Join Date: Mar 2002 Location: San Francisco, USA	*Where to actually get* magnetics for SMPS?** There are a lot of manufacturers for transformers, cores, and so forth, but you can't just call up Coiltronics and order five transformers. All the manufacturers have complicated sales channels and huge minimum orders. So where are you getting magnetics for your switching power supplies? I need to build two 30V, 4A supplies for a PWM amplifier.

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21st April 2003, 04:02 AM	#2
SkinnyBoy Banned Join Date: Nov 2002 Location: Adelaide, Australia	The cores from computer powersupply transformers..

21st April 2003, 05:41 AM	#3
jwb diyAudio Member Join Date: Mar 2002 Location: San Francisco, USA	I just broke open the power supply from my useless DEC Multia. It has a mystery transformer, but who can tell the specs? Googling for the part number yields nothing. Maybe I should try something made in this century.

21st April 2003, 06:22 AM	#4
SkinnyBoy Banned Join Date: Nov 2002 Location: Adelaide, Australia	wind your own...

21st April 2003, 06:59 AM	#5
Taligent diyAudio Member Join Date: Nov 2001 Location: Austin, TX	For a power supply, characterizing unknown magnetics shouldn't be out of reach. Iron powder or ferrite can be distinguished by winding a few turns and measuring the inductance. SpeakerWorkshop can do an adequate job of measuring inductance (as well as for characterizing drivers, go figure... ). Al can be determined from this, and then narrowing down the range of possible material types should be enough to make it worth trying out the magnetic for the application. For characterizing magnetics... Ferrite and iron powder info Transformers and ferrites Assessing unknown ferrite toroids Assuming the unknown magnetic is from a power supply, it is most likely ferrite, and the power handling can be estimated from the physical size of the ferrite. Try cross-referencing the size of the ferrite bits (EE, toroid?) against Ferroxcube or Amidon. Recycling ferrites from various switching power supplies has been the only source I've needed for magnetics thus far...computer power supplies really are quite useful as a source, considering that 250w power supplies are now out of favor due to the recent AMD/Intel practice of approving power supplies. Of course, DIY recycling notions aside, there are several places to order magnetics with non-corporate purchasing powers. The amateur radio community has been the trailblazer for this and other electronics parts for quite a while... Bytemark Palomar Engineers Dan's Small Parts - not as much in the way of magnetics, but fun to look through all the same HTH, Nikhil

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