transformer core material

Jeroen Belleman wrote:
====================
>
> > ** That is odd, toroidals are usually the best with -3dB responses to 100kHz. 
> > Just the fact the secondary is wound all over the primary does the trick.
>
> It surprised me too. I also measured an inter-winding capacitance of 
> 2nF, which strikes me as high. The drop-off was a resonance dip.

** You did have a suitable resistive load on the secondary ?? 



......   Phil 

Jeroen Belleman wrote:
> Tom Del Rosso wrote:
>> AIUI you use iron cores for low frequency and ferrite for high
>> frequency because ferrite doesn't get magnetized, so why couldn't
>> aluminum do the same?
>
> You *want* a transformer core to be easily magnetized! You don't
> want it to *stay* magnetized when the current goes to zero.

Of course that's what I meant. It has to conduct a magnetic field but it 
must not fight the induced field when it reverses.

I asked about the behavior of ferrite vs aluminum.

On 2021-08-26 02:39, Phil Allison wrote:
> Jeroen Belleman wrote:
> ====================
>>
>>> ** That is odd, toroidals are usually the best with -3dB responses to 100kHz.
>>> Just the fact the secondary is wound all over the primary does the trick.
>>
>> It surprised me too. I also measured an inter-winding capacitance of
>> 2nF, which strikes me as high. The drop-off was a resonance dip.
>
> ** You did have a suitable resistive load on the secondary ??
>

Just the 50 Ohm ports of my network analyzer.

Jeroen Belleman

On 2021-08-26 04:25, Tom Del Rosso wrote:
> Jeroen Belleman wrote:
>> Tom Del Rosso wrote:
>>> AIUI you use iron cores for low frequency and ferrite for high
>>> frequency because ferrite doesn't get magnetized, so why couldn't
>>> aluminum do the same?
>>
>> You *want* a transformer core to be easily magnetized! You don't
>> want it to *stay* magnetized when the current goes to zero.
>
> Of course that's what I meant. It has to conduct a magnetic field but it
> must not fight the induced field when it reverses.
>
> I asked about the behavior of ferrite vs aluminum.
>
>

The short answer is that aluminium is worse than nothing as a
transformer core. It *will* fight changing fields.

Jeroen Belleman

 Jeroen Belleman wrote:
===================
> 
> > ** You did have a suitable resistive load on the secondary ?? 
> >
> Just the 50 Ohm ports of my network analyzer. 
> 

**  So you paralled the windings or had them in series ? 

 15V or 30 V ? 

 Suitable =  close to full VA *if* the primary was operated at rated V. 

Unloaded trannys always ring like a bell. 


......   Phil 

On 2021-08-26 08:36, Phil Allison wrote:
>   Jeroen Belleman wrote:
> ===================
>>
>>> ** You did have a suitable resistive load on the secondary ??
>>>
>> Just the 50 Ohm ports of my network analyzer.
>>
>
> **  So you paralled the windings or had them in series ?
>
>   15V or 30 V ?
>
>   Suitable =  close to full VA *if* the primary was operated at rated V.
>
> Unloaded trannys always ring like a bell.

An RF network analyzer is a voltage source with a 50 ohm internal
impedance and a receiver with another 50 Ohm internal impedance.
I connected the source to one of the 15V windings of my transformer
and the receiver to the other. The source voltage is well below 1V
rms. Pretty far from the normal operating conditions of the transformer,
is true.

Jeroen Belleman

Jeroen Belleman wrote:
===================
>
>
> An RF network analyzer is a voltage source with a 50 ohm internal 
> impedance and a receiver with another 50 Ohm internal impedance. 
> I connected the source to one of the 15V windings of my transformer 
> and the receiver to the other. The source voltage is well below 1V 
> rms. Pretty far from the normal operating conditions of the transformer, 
> is true. 

** Drive voltage makes no difference at mid and high frequencies.
   Only a low ones when approaching core saturation. 
   Toridals use GOSS wound cores with tiny Imags. 

Fun fact: 

GOSS  =  grain oriented silicon steel. 
First invented by an engineer who's surname was Goss. 

https://en.wikipedia.org/wiki/Norman_P._Goss


.....   Phil 

Jeroen Belleman wrote:
> On 2021-08-26 04:25, Tom Del Rosso wrote:
>> Jeroen Belleman wrote:
>>> Tom Del Rosso wrote:
>>>> AIUI you use iron cores for low frequency and ferrite for high
>>>> frequency because ferrite doesn't get magnetized, so why couldn't
>>>> aluminum do the same?
>>>
>>> You *want* a transformer core to be easily magnetized! You don't
>>> want it to *stay* magnetized when the current goes to zero.
>>
>> Of course that's what I meant. It has to conduct a magnetic field
>> but it must not fight the induced field when it reverses.
>>
>> I asked about the behavior of ferrite vs aluminum.
>>
>>
>
> The short answer is that aluminium is worse than nothing as a
> transformer core. It *will* fight changing fields.

That implies that it will "stay magnetized" as you put it, so the answer 
is too short but thanks for trying.


-- 
 Defund the Thought Police 

On 2021-08-27 08:07, Tom Del Rosso wrote:
> Jeroen Belleman wrote:
>> On 2021-08-26 04:25, Tom Del Rosso wrote:
>>> Jeroen Belleman wrote:
>>>> Tom Del Rosso wrote:
>>>>> AIUI you use iron cores for low frequency and ferrite for high
>>>>> frequency because ferrite doesn't get magnetized, so why couldn't
>>>>> aluminum do the same?
>>>>
>>>> You *want* a transformer core to be easily magnetized! You don't
>>>> want it to *stay* magnetized when the current goes to zero.
>>>
>>> Of course that's what I meant. It has to conduct a magnetic field
>>> but it must not fight the induced field when it reverses.
>>>
>>> I asked about the behavior of ferrite vs aluminum.
>>>
>>>
>>
>> The short answer is that aluminium is worse than nothing as a
>> transformer core. It *will* fight changing fields.
>
> That implies that it will "stay magnetized" as you put it, so the answer
> is too short but thanks for trying.
>
>

Aluminium is a good conductor. There will be eddy currents induced
in it that will oppose any /change/ of magnetic field. Lenz law and
all that.But once external fields are removed and enough time has
passed for eddy currents to decay, there will be no field left over.

Jeroen Belleman

 Tom Del Rosso Total Fuckhead wrote:
============================
> 
> > The short answer is that aluminium is worse than nothing as a 
> > transformer core. It *will* fight changing fields.
>
> That implies that it will "stay magnetized" as you put it, so the answer 
> is too short but thanks for trying.
>  

**    FUCK  OFF  you vile, arrogant, POS, wog asshole 

      Never dream of coming back.




..... Phil