air-core inductors for PSU

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Phill

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#1
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
 
#3
to use torobar like this?

attachment.php



Phill
 
#6
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. :-(
 
#7
threefff said:
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
Click to expand...


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
 
#8
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
 
#10
Inductors for Power supply

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...
 
#15
Current transformers are what the name says.
A regular transformer has the objective to transform voltage.

That is why the picture on ebay looks different, the wiring goes through the core, not around it.
On a regular current transformer the core is the secondary wire.
With current transformers the right current can be set, or current can be measured.
Same Lorentz right hand rule stuff.
 
#17
you tell me how you will measure a 100 amp current.
The primary creates a flux in the core windings, the current of that one can be measured.
As i posted, with a normal current transformer the core you see is actually a coil.
Current transformers come in huge sizes.
Think for instance of a U-boat running on a few hundred batteries submerged, how to measure the huge currents driving the propulsion.
Shi*, talking boats again.
 
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