Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

John Curl's Blowtorch preamplifier part III
John Curl's Blowtorch preamplifier part III
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 15th September 2019, 08:49 PM   #28961
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Quote:
Originally Posted by Bonsai View Post
Best wishes in your move Richard. Trust it goes smoothly and you enjoy your tome over there. I spent 10 years in Asia and still get a hankering to go back. Awesome experience - I consider myself very lucky.

Thank you --- 10 years is long enough to begin to know it in some depth. It is very different... almost extreme compared to western culture. But, I am long over the culture shock. Been going there 20 or so years. Feels like home now.

-Richard

Quote:
Originally Posted by Ultima Thule View Post
Moving away from muricah' for good sounds so dramatic, is the 4th Reich about to collapse.. anyway hope your kidneys situation are in checks and balance, you might want to look into how to possibly reverse the situation with a holistic approach and that includes stage 5. Enjoy your new life Richard.

Cheers Michael
IMO it has collaspsed a long time ago. The party is over. Burnt toast here.

Kidney situation is a question mark. At my age, 12 more years is the end of it for most people anyway and I can nurse this kidney that long.

Most people dont know what will cause their death... only that you Will die. Its a big surprise awaiting you at the end. In my case, i already know so nothing to worry about.

Onward and upward... more learning to do, more adventures to have. More help and love to give. Got to hang in for my girl (well, looks more like a woman now). See her get launched into an engineering career. So I am positioning myself to help her and be more often able to visit -- being closer. She will stay in Asia.. maybe Thailand after she her EE degree. USA refused her admit into country in USA 3 times. Done trying. Its basically, because she comes from poor family in poor country. Subsistence farmers. Dont care if she got max SAT score possible in math and 160 IQ and top grades.

Old world Sarada / New world Sara.

67064328_882395702120370_6029895841748090880_n.jpg 51423112_410913679451822_6285247611888730112_n.jpg
THx-Richard
  Reply With Quote
Old 16th September 2019, 03:54 AM   #28962
hhoyt is offline hhoyt  United States
diyAudio Member
 
hhoyt's Avatar
 
Join Date: Mar 2010
Location: Chapel Hill, NC
John Curl's Blowtorch preamplifier part III
Quote:
Originally Posted by RNMarsh View Post
IMO it has collaspsed a long time ago. The party is over. Burnt toast here...
THx-Richard
I wish you the best in your new digs, Richard, I hope the move is invigorating and look forward to hearing from you here !

Best regards,
Howie
__________________
Howard Hoyt, CE - WXYC-FM 89.3
UNC Chapel Hill, NC - www.wxyc.org
  Reply With Quote
Old 16th September 2019, 05:52 AM   #28963
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Thank you.... and if you need some amps, power products, dac... what ever just email me with request.

rmarsh@calweb.com

-Richard
  Reply With Quote
Old 17th September 2019, 02:22 AM   #28964
gerhard is offline gerhard  Germany
diyAudio Member
 
gerhard's Avatar
 
Join Date: Oct 2005
Location: St. Wendel / Saar, SouthWest Germany
Quote:
Originally Posted by gpapag View Post
I have tried many times with Ohm meters, they show open circuit.
I havenít used a high voltage insulator tester though
George
I have heard of glowing orange ferrite beads having ground contact. (from a friend)
It depends on the material.

regards, Gerhard
__________________
"That's right!" shouted Vroomfondel, "we demand rigidly defined areas of doubt and uncertainty!" "We don't demand solid facts! What we demand is a total absence of solid facts. I demand that I may or may not be Vroomfondel!"
  Reply With Quote
Old 17th September 2019, 02:34 AM   #28965
phase is offline phase  United States
diyAudio Member
 
Join Date: Oct 2004
Thatís very commendable to support your family with a move like that, should be a win-win it sounds like.
  Reply With Quote
Old 17th September 2019, 03:11 AM   #28966
hhoyt is offline hhoyt  United States
diyAudio Member
 
hhoyt's Avatar
 
Join Date: Mar 2010
Location: Chapel Hill, NC
John Curl's Blowtorch preamplifier part III
Quote:
Originally Posted by gerhard View Post
I have heard of glowing orange ferrite beads having ground contact. (from a friend)
It depends on the material.

regards, Gerhard
In a properly matched RF system there will be no current flowing on the outside of the coax, just on the inside of the shield and outside surface of the inner conductor. When ice damages a broadcast antenna system and causes a severe mismatch, it can cause high common mode currents to flow. In these cases I have seen common mode chokes (which attenuate exterior coax shield currents) made using ferrite cores get hot enough to melt their plastic enclosures.

This is not due to their electrical conductivity though, just their resistance to induced flux.

Howie
__________________
Howard Hoyt, CE - WXYC-FM 89.3
UNC Chapel Hill, NC - www.wxyc.org
  Reply With Quote
Old 17th September 2019, 03:44 AM   #28967
keantoken is offline keantoken  United States
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Quote:
Originally Posted by hhoyt View Post
This is not due to their electrical conductivity though, just their resistance to induced flux.

Howie
So you are saying there is some way to produce heat from flux modulation that does not involve electrons? It could mechanically generate heat but you are saying it's a resistance to the induced flux as though that is the only thing.

The problem here is that the induced choke voltage is on the imaginary axis, so there can't be any power flow unless there is something in the magnetic loop converting flux modulation back to the imaginary axis (so it can be converted to real axis EMF). In the case of speakers, that is the motion of the coil through the flux. In the case of induction stoves, it is the magnetic inductivity of the pot (magnetic inductivity corresponds to cartesian conductance).

In a magnetic material the skin depth does not have to be smaller than the part in order for it to heat up. Even then the heat output is still proportional to power input. So you just need a very high AC current. IIRC ferrite is sintered, so while it may not be conductive between grains, the grains themselves could be conductive enough to have significant eddy currents. Since they are physically small, the skin depth may exceed their size. This only means that their shunt inductance will be small, so there will be little apparent change in inductance of the core, just the presence of a shunt resistance.
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer!
Need something built, repaired or modded? PM me and ask what I can do!

Last edited by keantoken; 17th September 2019 at 04:11 AM.
  Reply With Quote
Old 17th September 2019, 04:59 AM   #28968
hhoyt is offline hhoyt  United States
diyAudio Member
 
hhoyt's Avatar
 
Join Date: Mar 2010
Location: Chapel Hill, NC
John Curl's Blowtorch preamplifier part III
In an ideal magnetic material there is no loss, but in practical ferrite materials, there is hysteresis loss as well as what you state, eddy current losses. Many MnZn ferrites (mix 31, 75) have relatively low bulk resistivities, mix 31 for example is specified at 3000 ohms per cm^3.

Cheers,
Howie
__________________
Howard Hoyt, CE - WXYC-FM 89.3
UNC Chapel Hill, NC - www.wxyc.org
  Reply With Quote
Old 17th September 2019, 11:46 AM   #28969
gerhard is offline gerhard  Germany
diyAudio Member
 
gerhard's Avatar
 
Join Date: Oct 2005
Location: St. Wendel / Saar, SouthWest Germany
Quote:
Originally Posted by hhoyt View Post
In a properly matched RF system there will be no current flowing on the outside of the coax, just on the inside of the shield and outside surface of the inner conductor.
Howie
That does not even depend on matching. You can have huge SWR on a coax and no current outside.

These beads were carrying DC power. Some ferrite mixes conduct.

regards, Gerhard
__________________
"That's right!" shouted Vroomfondel, "we demand rigidly defined areas of doubt and uncertainty!" "We don't demand solid facts! What we demand is a total absence of solid facts. I demand that I may or may not be Vroomfondel!"
  Reply With Quote
Old 17th September 2019, 02:12 PM   #28970
gpapag is offline gpapag  Greece
diyAudio Moderator
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
John Curl's Blowtorch preamplifier part III
Quote:
Originally Posted by gerhard View Post
I have heard of glowing orange ferrite beads having ground contact. (from a friend)
It depends on the material.
Hi Gerhard.
Reading your later posts I have to make a delayed clarification, that I was referring to loudspeaker motor ferrite and I think we have to think of the environment (EC voltage, current, frequency range) that they operate into.

That said, thank you for the info on RF ferrites, your input has produced a welcome exchange of info among knowledgeable members.

George
__________________
["Second Law is a bitch." - SY]
["I insist on respecting the means of the average person working in their garage/basement." -Scott Wurcer]
  Reply With Quote

Reply


John Curl's Blowtorch preamplifier part IIIHide 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

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 08:52 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki