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The right kind of inductor!
The right kind of inductor!
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Old 15th April 2018, 06:48 PM   #21
Michael Rothacher is offline Michael Rothacher  United States
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The right kind of inductor!
Oon,

C'mon, buddy.

Horse.

Water.

We've led you right there.

Drink and enjoy.

Or, try something else and see what happens.
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Old 16th April 2018, 12:02 AM   #22
oon_the_kid is offline oon_the_kid  Malaysia
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Well, you see. I have already built many amps based on that configuration. Yup I have built based on the Hammond 159 60mH 2A and the 193V 150mH 3A. However they are quite expensive. Now here I have some AC choke at $10 of comparable value. So the question is will it work too, if not, why? I have read somewhere you need to give a lot more allowance as the DC +AC will give a higher peak current. So you need the extra allowance not to saturate the core.

So you can bring a horse to water, but I am curious, what if you gave it beer.

As far as my theory can tell, as long as you don't saturate the core and the core doesn't become ferro magnetic, it should work.

So I am still looking for someone to tell me physically why it will not work..

Oon
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Old 16th April 2018, 02:38 AM   #23
PRR is offline PRR  United States
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The common-mode choke expects the large current to -cancel- in the core. Power goes in one winding, out the other winding, no core flux.

Alternate reality-check: Michael is using the 2.5 Pound choke just as it was made to be used (large DC and small-to-large AC). The RN152-- is 2.5 *ounces*, 1/16 the stuff in it (and near 1/16 the cost). Is Hammond not smart enough to do it better? Or are they really aimed at *different* jobs, one about 1/16 the "stuff" of the other due to imperfect cancellation?

But hey, 4 bucks is less than lunch. Do it. (You may need added resistance to have something to DC bias on.) My expectation is, with high unbalanced DC current, the inductance will go-away 99%, lower cut-off above 1KHz.
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Old 16th April 2018, 03:22 AM   #24
oon_the_kid is offline oon_the_kid  Malaysia
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Quote:
Originally Posted by PRR View Post
The common-mode choke expects the large current to -cancel- in the core. Power goes in one winding, out the other winding, no core flux.

Alternate reality-check: Michael is using the 2.5 Pound choke just as it was made to be used (large DC and small-to-large AC). The RN152-- is 2.5 *ounces*, 1/16 the stuff in it (and near 1/16 the cost). Is Hammond not smart enough to do it better? Or are they really aimed at *different* jobs, one about 1/16 the "stuff" of the other due to imperfect cancellation?

But hey, 4 bucks is less than lunch. Do it. (You may need added resistance to have something to DC bias on.) My expectation is, with high unbalanced DC current, the inductance will go-away 99%, lower cut-off above 1KHz.
Ah... More like what I was looking for. So for common mode choke, the two coils are wound to oppose each other and cancel the balanced signal.

So the inductor only sees the difference in the signal between the two lines. So you reckon if I put DC through it, I might saturate the core?

Might give it a shot to see what happens, just part of learning..

Oon
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Old 16th April 2018, 03:27 AM   #25
daqvin_carter is offline daqvin_carter  United States
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Another note about the common mode choke is it needs much fewer turns to get 68MH. This is because it it has a higher permiability (guessing more than 10) compared to the Hammond choke (maybe 5).
Higher permiability cores saturate much easier which is not good for a MOFO amp.
You might get half a watt or less before saturation becomes a problem.
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Old 16th April 2018, 05:09 AM   #26
Zen Mod is offline Zen Mod  Serbia
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The right kind of inductor!
core saturation.

'nuff said.
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Old 16th April 2018, 11:14 AM   #27
Michael Rothacher is offline Michael Rothacher  United States
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The right kind of inductor!
Quote:
Originally Posted by oon_the_kid View Post
So you can bring a horse to water, but I am curious, what if you gave it beer...


I'll buy you a beer. I've tried all kinds of chokes, iron and air core crossover inductors, etc. I haven't tried a common mode choke like the one you're interested in. My guess based on reality is that you'll be seeing a lot of distortion at best.

But as you say, it's only $4 so why don't you try it and let us know how it works out.
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Old 16th April 2018, 11:19 AM   #28
Zen Mod is offline Zen Mod  Serbia
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The right kind of inductor!
well , I had my share of brilliant ideas , no doubt

knowing my self , I'm not yet finished .......

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