air-core inductors for PSU

[Phill]

hello
I would like to build a aleph 5 with CLC PSU

can i use air-core inductors, which is used to filter loudspeaker ?
did some already do it with good result?

ref SA2.2 or SA2.7 :
http://cyber.asp-hebergement.com/demo2/icp1971/sair.pdf

SELF A AIR 2,7mH 0,27 Ohm 500W
fil cuivre pur emaille 2mm²
poids environ 670gr Diam 70 ht 59mm


it is difficult to find iron core coils of valeure lower than 3 mH


thanks
Phill

[Magura]

I would be careful using inductors for PSU purposes, that are not intended for such.

Magura

[Phill]

to use torobar like this?




Phill

[Magura]

Something like this http://www.diyaudio.com/forums/showt...058#post503058

or this http://www.briangt.com/gallery/magura-inductors


Magura

[wuffwaff]

Hi Phil,


the torobars seem to be working just fine. They didn´t even saturate at 10A. (it´s the 2,2mH / 0,12Ohm version)

William

[threefff]

Hi Phill,

I'm just about to build a pair of aleph2s with air core inductors in the PSU. I already tested the PSUs and they work just as expected. The only thing I still bother about is the alternating magnetic field, which is far bigger than with a closed iron core, and might cause hum in the amplifier.

Cheers
Thomas

P.S. I forgot their size, not just compact, I would say: Cylinder, 80 mm long, 75 in diameter with copper wire of 2,5 mm dia. for just 1 or two mH. :-(

[Phill]

Originally posted by threefff
Hi Phill,

The only thing I still bother about is the alternating magnetic field, which is far bigger than with a closed iron core, and might cause hum in the amplifier.

Cheers
Thomas

I will want to make 2 cases: one for the PSU and one for the amplifier. the problem is decreased a little ???

which is your choice for the closed iron core ?

thank you
Phill

[threefff]

Hi Phill,

yes, two cases will lower the magnetic field seen by the amplifier itself, depending on µr of the case and the distance of the two cases. If you want to go into detail, just look out for vizimag. It's a free tool to simulate magnetic fields. It's 2d and not very handy, but it works.

As you probably already know, the problem with the iron core is the maximum magnetic flux density of the used metal and you need this metal in thin plates to avoid "turbulent" currents (or however they say in english). Best thing would be to buy a ready made core or even a ready made coil like the torobars (google them). They appear reasonably to me. 12 $ for 10mH and some 6 to 8 Amperes, if I recall correctly, compared to 6 Euros for the copper wire I used.

I just have these beasts hangin' around in my cases, wasting space and contaminating their environment with EMV.

Cheers
Thomas

[Phill]

after much of reading, I made a temporary decision!

PS question - CLC vs C filtering

I will build a PSU CRC
the budget will be lighter !!!
later I would test with coil, and I could compare

I would return quickly for other questions!
large a thank you with all
Phill

[zlast]

Are these inductors suitable for the Aleph power supply?:

http://www.jwmiller.com/pdf2/8100.pdf

Specifically the model 8120 (2.4 MH rated at 17 amps)

THe product documentation states the model 8120 is a "Common Mode Inductor" . Looking at the schematic shows it is actually 2 inductors wound around one ferrite core. Also between which pin combination is this inductor rated at 17 amps? There are 4 pins, do I use 1+2 on one side and 3+4 on the other, or pins 1+4 on one side and 2+3 on the other? Hope this doesnt confuse anyone as much as it does me...