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Re: Ever heard of this...

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On 02/10/2017 10:35 AM, Jim Thompson wrote:
> On Sat, 11 Feb 2017 01:49:23 +1100, Chris Jones
> <lugnut808@spam.yahoo.com> wrote:
>
>> On 09/02/2017 09:19, Jim Thompson wrote:
>>> On Wed, 8 Feb 2017 17:04:41 -0500, Phil Hobbs
>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>
>>>> On 02/08/2017 04:58 PM, Jim Thompson wrote:
>>>>> Ever heard of this...
>>>>>
>>>>> Client has issues with audio transformers... at low signal levels they
>>>>> exhibit roll-off in coupling at low frequencies, like -10dB at 50Hz
>>>>>
>>>>> But high signal _levels_ do not.
>>>>>
>>>>> Strange?  Or a known phenomenon?
>>>>> 		
>>>>>                                         ...Jim Thompson
>>>>>
>>>>
>>>> Sure.  Lots of core materials have lower permeability at low flux
>>>> levels--it's the magnetic version of traps in semiconductors.
>>>>
>>>> Cheers
>>>>
>>>> Phil Hobbs
>>>
>>> So there's no cure?  I was pondering current drive, but it doesn't
>>> sound like that would help?
>>> 		
>>>                                         ...Jim Thompson
>>>
>>
>> Maybe add another secondary winding, and use it for negative feedback in
>> the circuit that drives the primary, a bit like old valve audio power
>> amplifiers did.
>>
>> You would want the feedback secondary and the real secondary to have
>> similar coupling to the primary.
>
> Yes.  The client found this...
>
> <http://www.analog-innovations.com/SED/Lundahl_Amplifier-Transformer_Combination%20Design.pdf>
> 		
>                                         ...Jim Thompson
>
Interesting.  (I've never used an audio transformer in real life--just 
pulse and RF.)

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

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Ever heard of this... Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-08 14:58 -0700
  Re: Ever heard of this... Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 17:04 -0500
    Re: Ever heard of this... Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-08 15:19 -0700
      Re: Ever heard of this... Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 17:27 -0500
        Re: Ever heard of this... Tim Wescott <seemywebsite@myfooter.really> - 2017-02-08 17:35 -0600
          Re: Ever heard of this... pcdhobbs@gmail.com - 2017-02-08 15:52 -0800
          Re: Ever heard of this... bitrex <bitrex@de.lete.earthlink.net> - 2017-02-08 19:04 -0500
      Re: Ever heard of this... John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-08 17:15 -0800
      Re: Ever heard of this... George Herold <gherold@teachspin.com> - 2017-02-08 17:56 -0800
        Re: Ever heard of this... Pimpom <Pimpom@invalid.com> - 2017-02-09 13:05 +0530
      Re: Ever heard of this... Chris Jones <lugnut808@spam.yahoo.com> - 2017-02-11 01:49 +1100
        Re: Ever heard of this... jrwalliker@gmail.com - 2017-02-10 06:59 -0800
          Re: Ever heard of this... Joerg <news@analogconsultants.com> - 2017-02-10 07:29 -0800
        Re: Ever heard of this... Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 08:35 -0700
          Re: Ever heard of this... Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-10 11:20 -0500
          Re: Ever heard of this... John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-10 08:37 -0800
            Re: Ever heard of this... makolber@yahoo.com - 2017-02-10 08:48 -0800

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