John Curl's Blowtorch preamplifier part II - Page 3276 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th January 2013, 02:55 PM   #32751
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Coax symmetry is not the problem. The issue with coax is that the spacing between inner and outer is large enough that normal skin effect dominates. Now I believe that skin effect and proximity effect are merely auto and mutual versions (respectively) of the same thing so will behave in the same way, but I am not sure everyone agrees so demonstrating nothing strange with skin effect might not convince those looking for strange proximity effects.

You would probably need to setup something where conductor spacing is smaller than skin depth so proximity effect dominates, as may sometimes be the case for audio. Maybe an air-cored inductor or transformer, but with well-encapsulated windings so no physical movement is possible?
  Reply With Quote
Old 16th January 2013, 03:08 PM   #32752
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by scott wurcer View Post
One rule NEVER ever sign an NDA with kooks.
Earnest inventors often wonder why large companies turn them away when they show up at the door with big grins and "great new ideas".

My other favorite are the calls I get from people with "great ideas" who in essence wind up saying "with my great idea, and your expertise to make it work, we'll split 50-50 and both get rich!"
  Reply With Quote
Old 16th January 2013, 03:25 PM   #32753
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by bcarso View Post
Earnest inventors often wonder why large companies turn them away when they show up at the door with big grins and "great new ideas".
Don't they realize the simple fact they ring the door's bell is an insult to the manager of the company and the money he invested in the R&D department ?
__________________
Ultimate Protection and more.The Only Source of Knowledge is experience, everything else is just information” ©A. Einstein

Last edited by Esperado; 16th January 2013 at 03:37 PM.
  Reply With Quote
Old 16th January 2013, 03:44 PM   #32754
mikelm is offline mikelm  England
diyAudio Member
 
Join Date: May 2003
Location: England
Send a message via Yahoo to mikelm
Don't the managers realise that their "not invented here" closed minded attitude probably loses them some unique opportunities - other side of the coin
  Reply With Quote
Old 16th January 2013, 03:55 PM   #32755
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
I agree, with the eyes stuck on daily work and efficiency requisites, a R&D department is often the worse place to get innovative ideas. Even if it is in your nature to look at the things upside down. Part of the Peter principle.
__________________
Ultimate Protection and more.The Only Source of Knowledge is experience, everything else is just information” ©A. Einstein

Last edited by Esperado; 16th January 2013 at 03:58 PM.
  Reply With Quote
Old 16th January 2013, 04:39 PM   #32756
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Quote:
Originally Posted by magnoman View Post
George
At least for the current crowding effect being discussed wouldnt the co-ax symmetry prevent it all together?
Thanks
-Antonio
Antonio , as DF96 said this symmetry is not the problem.
The "current crowding" effect in the coaxial expresses itself as current concentrating at the outermost of centre conductor’s diameter and at the innermost of shield’s diameter. At both conductors, the cross-sectional current carrying area diminishes.

Quote:
Originally Posted by DF96 View Post
Now I believe that skin effect and proximity effect are merely auto and mutual versions (respectively) of the same thing so will behave in the same way
This is my understanding too

Quote:
but I am not sure everyone agrees
That’s an invitation for discussion

Quote:
The issue with coax is that the spacing between inner and outer is large enough.
The beauty and convenience of theoretical approach is that this distance can be made minute. Distortions (if any) can be theoretically derived. Effect of radial distance increase up to a real physical size can be calculated.

On the theoretical level of approach, the study is done on the cross section of the coaxial line, i.e. a slice having an axial length dL.
If result are then integrated over a length 1000dL or 100000dL the calculated distortions at the dL slice will I guess be multiplied accordingly (?).

Then, a good length of a coaxial cable with a small diameter (e.g. RG58) can be used in experiments to test the theoretical predictions.

George
__________________
["Second Law is a bitch." - SY] ["The Road To Heaven:Specify the performance & accept the design. The Road To Hell:Specify the design & accept the performance"-Bruno Putzeys]
  Reply With Quote
Old 16th January 2013, 04:41 PM   #32757
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
I remember back in 1975 while attending an AV convention in Montreux, I tried to interest Neve 'engineers' in my measurements of the ceramic caps that they were using in their modules at the time. I got a big affront telling me that everything they do is a 'trade-secret' and they don't wish to discuss any new input. '-)
  Reply With Quote
Old 16th January 2013, 04:44 PM   #32758
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by magnoman View Post
jn,

That would help but I think I'm following your basic argument just not quite how it produces a second.

If one accepts the dI/dT dependency and that this effect only increases the crowding resistance then I can understand how for a sinewave this would result in cos modulation from the dI/dT and the absolute value to account for only increasing resistance.
But from there I see this modulation producing steeper slopes around the cross-overs, local minimums at the peaks, all symmetrical between positive and negative going cycles of the sinewave. Why wouldn't this symmetry measure as a dominant 3rd?

Real or not at least for a series feedback divider the effects should cancel out (between the high side and low side resistors).

Thanks
-Antonio
Well easy enough to plot the FFT's, for an R = Ro(1 + a*abs(cos(wt)) there are all even harmonics but sin(wt)/(Ro(1 + a*abs(cos(wt)) ) is all odd. Where a is some very small factor.
__________________
Silence is so accurate.
  Reply With Quote
Old 16th January 2013, 04:47 PM   #32759
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally Posted by Esperado View Post
I agree, with the eyes stuck on daily work and efficiency requisites, a R&D department is often the worse place to get innovative ideas. Even if it is in your nature to look at the things upside down. Part of the Peter principle.
That one has me scratching my head in puzzlement. The barrier to accepting ideas thrown over the transom (besides the obvious, that most of them are a colossal waste of time) is that if the idea is a good one, you're 99.99% certain to end up in expensive litigation even if it's an idea that already existed within the company. I've worked in and run several different R&D organizations and there's no shortage of really interesting and original ideas that come out of them.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 16th January 2013, 04:55 PM   #32760
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by SY View Post
That one has me scratching my head in puzzlement. The barrier to accepting ideas thrown over the transom (besides the obvious, that most of them are a colossal waste of time) is that if the idea is a good one, you're 99.99% certain to end up in expensive litigation even if it's an idea that already existed within the company. I'veworked in and run several different R&D organizations and there's no shortage of really interesting and original idea that come out of them.
Litigation, or rather its avoidance, is really the key here. It is sooo expensive, in money but especially in time, even if you "win". And there is a natural but often unjustified notion that the "big" company is simply at fault to begin with. Sometimes they are, and being big does often engender arrogance and worse. But the romantic paradigm of the little guy getting the helical inclined plane (or however the writers of Big Bang Theory put it) is also not always accurate.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 11:11 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2