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Old 19th December 2002, 05:13 AM   #11
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Quote:
If there is a way of DIYing the the inductors then it might come off the back burner!
Of all the passive electronic components, inductors are by far the easiest to DIY.
You just need a suitable magnetic core and wire and some patience.

Regards

Charles


P.S.: To be honest, you need to know how to calculate them as well of course but if this is the main problem I can assist.
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Old 19th December 2002, 06:45 AM   #12
hacknet is offline hacknet  Singapore
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6.8 uh iz not hard to find rite? i just saw some in the shop
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Old 19th December 2002, 08:45 AM   #13
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hi hacknet

Unfortunately it is 68 uH and not 6.8 uH. I think for an active subwoofer where the amp is placed close to the woofer, the filter with the highest cutoff frequency could be used, i.e. the one with a 47 uH coil.

Regards

Charles
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Old 19th December 2002, 08:55 AM   #14
hacknet is offline hacknet  Singapore
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cant i series it or parellel it so dat it adds up... iz like $0.10 per pcs
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Old 19th December 2002, 09:05 AM   #15
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Hi hacknet

The inductance would indeed add up if they were connected in series.
Depending on the type of coil this may result in something that lies somewhere between "not very elegant" and "not advisible".

What I'd like to know is the max current those 6.8uH inductors can carry, could it be it's just a few Miliampères (at that price) ?

Regards

Charles
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Old 19th December 2002, 09:08 AM   #16
hacknet is offline hacknet  Singapore
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it look a little like a toroidal trafo only smaller... this was from a shop that collect junked pcbs and recovers the parts so that is why it is so cheap...
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Old 19th December 2002, 10:14 AM   #17
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diy inductor? high current?

no problem:

16mm^2 should be good for 10 times more current than you want, this should be about 880uH
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Old 19th December 2002, 12:05 PM   #18
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Hi Till

I wouldn't see any problems with this coil if it was used for a >20kW amplifier.
But you will need two of them for a H-bridge.......
I don't like the idea of using coils as large as the subwoofer's driver.
Apart from that you would run into serious EMC problems with air cored coils that large !!!!

A solution i haven't tried yet would be an air-cored toroidal coil but this would require more windings than a cylindrical coil but have less stray-field.

BTW: The maximum current in an inductor isn't determined solely by the wire diameter, the dominant part is played by the core saturation.
A feasible workaround is to use a core with an airgap.

Regards

Charles
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Old 19th December 2002, 12:13 PM   #19
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Hey two would be no prob, i have more than 20Kg of this material here at the moment.... EMC - yes, i hope nobody aroung knows what i do with this - i try to make a little induction - melting - ofen with these. What about metal enclosure? I build one out of 4mm steel for toroids. Should help.

For the amp i would use some like these i made for the crossovers :

homemade inductor - sheesh!!

posting No. 10
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Old 19th December 2002, 12:19 PM   #20
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I alrerady HAVE used one of those:

http://www.epcos.com/inf/80/db/fer_01/02440248.pdf

Regards

Charles
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