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edonion 12th November 2004 11:32 PM

Amorphous core transformers only work above 20KHz?
Hello everybody!

I've recently acquired “amorphous C-cores" in number AMS-CC1-190083-U0N0R, just like attached pdf.

When I tried to determine the number of turn/volt, I frightened myself when verifying that these cores only work above the 20KHz. :eek:

Was I thrashed or should this result be waited? :xeye:
Can anybody help? :)



bear 15th November 2004 02:19 AM

Step one, find the decimal point that got moved?

Step two, contact the engineering support at the company, and explain what you want and what you are trying to do.

Since there have been tube output transformers wound with amorphous C cores already, we know it can be done.

The question, iirc, is if the material you got happens to be large enough for the application, and has sufficient permeability at the frequencies of interest. I think that's the bottom line...

Not sure which product ur looking at, since there was no pdf with your post... (dunno how to do that bit myself...). And you didn't specify a webpage or product number.

_-_-bear :Pawprint:

edonion 15th November 2004 11:05 AM

I think the pdf is very large. Pleas try download it from



edonion 15th November 2004 11:14 AM

On the other hand I think that the core heated up too much during the rectification process.

I noticed that it is inflated and deformed the close to the zone where the rectification millstone was passed.

Tanks again


Gasho 15th November 2004 10:10 PM

The core can work at lower frequency than 20KHz. Every metal core works in lower region too. Maybe your transformers are designed for other purpose, like switch power supply. There is no need for large number off wire turns in coils becouse they work with high frequencyes (50-100KHz). Higher the frequency , higher voltage is induced in secondary coil.

Colt45 15th November 2004 10:44 PM

I'm too damn lazy to read the PDF,

But as frequency increases, less inductance is required to do the job. so. if the core is constant, you need less windings for a higher frequency.

so it's probably wound to work for 20khz, and will not provide enough inductance for lower freq's. i think. ;)

edonion 15th November 2004 11:55 PM


Perhaps you want to refer to the following formula:

N= V*10000/(4.44*f*Ac*Bmax)


N = number of turns
V = Voltage in Vrms
f = frequency in Hertz
Ac = area of section of the core in cm2
Bmax = Maximum induction allowed in Teslas

In my second experience I had 800 turns wound in a core of 9,5 cm2.

I had a setup constituted by a variac a lamp of 60W in serious and the referred bobbin.

I noticed that lamp lit with 170V - 50Hz.
This means that the core was saturated 0.99 Tesla.
According to datasheet this should only happen at 1.5 Tesla

That is the reason I think I was tricked!

Would you not think like this?



bear 17th November 2004 04:23 PM


The gap will effect the saturation point.


Sch3mat1c 17th November 2004 07:29 PM


Originally posted by bear

The gap will effect the saturation point.


And mu. Actually, it flattens out the mu (in the same brute-force way that a very large bleeder resistor will improve regulation of a power supply, at the cost of a lot of power), with the side-effect that saturation is greater as well (because actually, mu is lower so the B is lower for the same amp-turns....etc....).


edonion 17th November 2004 10:51 PM


Yes of course!
Due to the deformation of the junction area of the two " C " of the core, I have a unwanted gap.


I also think so.

Because the material heated up too much. There it is the reason to have lost some physics characteristics, such as permeability, maxim saturation flux, etc.



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