Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > sci.electronics.design > #446877 > unrolled thread
| Started by | Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> |
|---|---|
| First post | 2017-02-08 14:58 -0700 |
| Last post | 2017-02-10 08:48 -0800 |
| Articles | 17 — 13 participants |
Back to article view | Back to sci.electronics.design
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
| From | Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> |
|---|---|
| Date | 2017-02-08 14:58 -0700 |
| Subject | Ever heard of this... |
| Message-ID | <9s4n9clvnbkhersuoet4si2ak28la2po48@4ax.com> |
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
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Thinking outside the box... producing elegant solutions.
[toc] | [next] | [standalone]
| From | Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> |
|---|---|
| Date | 2017-02-08 17:04 -0500 |
| Message-ID | <g-ydnT9t59xwCAbFnZ2dnUU7-TGdnZ2d@supernews.com> |
| In reply to | #446877 |
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 -- 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
[toc] | [prev] | [next] | [standalone]
| From | Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> |
|---|---|
| Date | 2017-02-08 15:19 -0700 |
| Message-ID | <fa6n9cl64o1356n8uk7a0i99fhnsqu6t83@4ax.com> |
| In reply to | #446880 |
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
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Thinking outside the box... producing elegant solutions.
[toc] | [prev] | [next] | [standalone]
| From | Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> |
|---|---|
| Date | 2017-02-08 17:27 -0500 |
| Message-ID | <9MKdnbLVhdOwBgbFnZ2dnUU7-cPNnZ2d@supernews.com> |
| In reply to | #446883 |
On 02/08/2017 05:19 PM, 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 > Different core material, or an out-of-band bias signal, as in tape heads. 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
[toc] | [prev] | [next] | [standalone]
| From | Tim Wescott <seemywebsite@myfooter.really> |
|---|---|
| Date | 2017-02-08 17:35 -0600 |
| Message-ID | <DtqdnW2HLKKjNgbFnZ2dnUU7-IGdnZ2d@giganews.com> |
| In reply to | #446887 |
On Wed, 08 Feb 2017 17:27:05 -0500, Phil Hobbs wrote: > On 02/08/2017 05:19 PM, 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 >> >> > Different core material, or an out-of-band bias signal, as in tape > heads. So, I read Jim's questions and think "ooh, I know the answer!", then Phil answers it. Twice. In a row. Hmph. (Yes, this IS a contest). If you're clever you can probably tailor the bias signal as needed, to reduce power drain and maintain sufficient overhead. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com I'm looking for work -- see my website!
[toc] | [prev] | [next] | [standalone]
| From | pcdhobbs@gmail.com |
|---|---|
| Date | 2017-02-08 15:52 -0800 |
| Message-ID | <12d677da-cb6f-4176-8843-fc837e4b7115@googlegroups.com> |
| In reply to | #446905 |
>So, I read Jim's questions and think "ooh, I know the answer!", then Phil >answers it. Twice. In a row. Hmph. Don't feel bad--I'm stuck in bed getting over pneumonia, and am sufficiently recovered to be excruciatingly bored, so I'm checking SED much more often than someone with other options. If somebody asks something about systems with multiple inputs and outputs, I promise I'll be quiet as a mouse. ;) Cheers Phil Hobbs
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-02-08 19:04 -0500 |
| Message-ID | <rmOmA.25797$L77.4782@fx38.iad> |
| In reply to | #446905 |
On 02/08/2017 06:35 PM, Tim Wescott wrote: > On Wed, 08 Feb 2017 17:27:05 -0500, Phil Hobbs wrote: > >> On 02/08/2017 05:19 PM, 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 >>> >>> >> Different core material, or an out-of-band bias signal, as in tape >> heads. > > So, I read Jim's questions and think "ooh, I know the answer!", then Phil > answers it. Twice. In a row. Hmph. > > (Yes, this IS a contest). > > If you're clever you can probably tailor the bias signal as needed, to > reduce power drain and maintain sufficient overhead. > Current drive sounds good as you can RSense and filter to get a control voltage representing the average flux in the core, and use that to control your out-of-band bias oscillator just summed into the signal, to keep the flux above some minimum constant
[toc] | [prev] | [next] | [standalone]
| From | John Larkin <jjlarkinxyxy@highlandtechnology.com> |
|---|---|
| Date | 2017-02-08 17:15 -0800 |
| Message-ID | <fjgn9c9e8nnhth74ood0mafgdfo00sba9n@4ax.com> |
| In reply to | #446883 |
On Wed, 08 Feb 2017 15:19:38 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> 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 Real or approximate zero-flux mode would certainly help. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
[toc] | [prev] | [next] | [standalone]
| From | George Herold <gherold@teachspin.com> |
|---|---|
| Date | 2017-02-08 17:56 -0800 |
| Message-ID | <c46d4e35-f6ed-4cd8-8f42-2d349b75c61b@googlegroups.com> |
| In reply to | #446883 |
On Wednesday, February 8, 2017 at 5:19:49 PM UTC-5, 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? Knowing little about magnetics, could you turn on some DC bias at low signal levels? George H. > > ...Jim Thompson > -- > | James E.Thompson | mens | > | Analog Innovations | et | > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > | E-mail Icon at http://www.analog-innovations.com | 1962 | > > Thinking outside the box... producing elegant solutions.
[toc] | [prev] | [next] | [standalone]
| From | Pimpom <Pimpom@invalid.com> |
|---|---|
| Date | 2017-02-09 13:05 +0530 |
| Message-ID | <o7h63m$6cs$1@news.albasani.net> |
| In reply to | #446947 |
On 2/9/2017 7:26 AM, George Herold wrote: > On Wednesday, February 8, 2017 at 5:19:49 PM UTC-5, Jim Thompson wrote: >> On Wed, 8 Feb 2017 17:04:41 -0500, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 02/08/2017 04:58 PM, Jim Thompson wrote: >>>> Ever heard of this... >>>> >>>> Client has issues with audio transformers... at low signal levels they >>>> exhibit roll-off in coupling at low frequencies, like -10dB at 50Hz >>>> >>>> But high signal _levels_ do not. >>>> >>>> Strange? Or a known phenomenon? >>>> >>>> ...Jim Thompson >>>> >>> >>> Sure. Lots of core materials have lower permeability at low flux >>> levels--it's the magnetic version of traps in semiconductors. >>> >>> Cheers >>> >>> Phil Hobbs >> >> So there's no cure? I was pondering current drive, but it doesn't >> sound like that would help? > Knowing little about magnetics, could you turn on some DC bias > at low signal levels? > DC could introduce distortion, maybe more easily than HF AC and will need some tweaking to get the best results It *was* used in many cheap portable tape recorders.
[toc] | [prev] | [next] | [standalone]
| From | Chris Jones <lugnut808@spam.yahoo.com> |
|---|---|
| Date | 2017-02-11 01:49 +1100 |
| Message-ID | <RpknA.626432$Zf5.311254@fx41.am4> |
| In reply to | #446883 |
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.
[toc] | [prev] | [next] | [standalone]
| From | jrwalliker@gmail.com |
|---|---|
| Date | 2017-02-10 06:59 -0800 |
| Message-ID | <8eac49d7-743f-49ad-9a9a-c98044b255a9@googlegroups.com> |
| In reply to | #447149 |
On Friday, 10 February 2017 14:49:26 UTC, Chris Jones 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. Why would this only affect low frequencies? John
[toc] | [prev] | [next] | [standalone]
| From | Joerg <news@analogconsultants.com> |
|---|---|
| Date | 2017-02-10 07:29 -0800 |
| Message-ID | <eg64i0Fh95tU1@mid.individual.net> |
| In reply to | #447150 |
On 2017-02-10 06:59, jrwalliker@gmail.com wrote: > On Friday, 10 February 2017 14:49:26 UTC, Chris Jones 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. > > Why would this only affect low frequencies? > At higher frequencies less inductance is needed and the impedance of the transformer will still be sufficient despite the reduced permeability. Not so at low frequencies. It's the same with RF transformers such as baluns. There it is more extreme in that at really high frequencies the core wouldn't even have to be there. -- Regards, Joerg http://www.analogconsultants.com/
[toc] | [prev] | [next] | [standalone]
| From | Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> |
|---|---|
| Date | 2017-02-10 08:35 -0700 |
| Message-ID | <1cnr9c9ctb6i13it5o42qtu7eateeckh4a@4ax.com> |
| In reply to | #447149 |
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
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Thinking outside the box... producing elegant solutions.
[toc] | [prev] | [next] | [standalone]
| From | Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> |
|---|---|
| Date | 2017-02-10 11:20 -0500 |
| Message-ID | <o7kp44$h8k$2@dont-email.me> |
| In reply to | #447153 |
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
[toc] | [prev] | [next] | [standalone]
| From | John Larkin <jjlarkin@highlandtechnology.com> |
|---|---|
| Date | 2017-02-10 08:37 -0800 |
| Message-ID | <32rr9cl3jpe8bj5tvrbe2p9nr6ofsjvht2@4ax.com> |
| In reply to | #447153 |
On Fri, 10 Feb 2017 08:35:19 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> 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 Nice oscillator circuits! -- John Larkin Highland Technology, Inc lunatic fringe electronics
[toc] | [prev] | [next] | [standalone]
| From | makolber@yahoo.com |
|---|---|
| Date | 2017-02-10 08:48 -0800 |
| Message-ID | <46705d85-ba01-4240-9323-03caa3e97d3e@googlegroups.com> |
| In reply to | #447166 |
> >>>>> > >>>>> 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. > > > >>> if you put a low frequency sine wave through the transformer, does it appear distorted, resembling crossover distortion? or is it just that the client is making a measurement error? the xformer attenuates low frequencies for all the usual reasons, but if you drive it harder, it distorts, and the clients measurements incorrectly indicate that the amplitude of the fundamental increased? Mark
[toc] | [prev] | [standalone]
Back to top | Article view | sci.electronics.design
csiph-web