John Curl's Blowtorch preamplifier part II - Page 1101 - diyAudio
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Old 11th March 2011, 05:46 AM   #11001
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Quote:
Originally Posted by jam View Post
Steve,
..............here is something more your speed.
Sorry, but that's waaaaaay over my head. Gimme a call tomorrow and 'splain it to me.

se
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Old 11th March 2011, 09:57 AM   #11002
Roxanne is offline Roxanne  United Kingdom
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Quote:
Originally Posted by scott wurcer View Post
Download any recent issue of Elecktor and there are numerous listings for services at any level. I use ExpressPCB $51 for three 1/2 eurosize boards. Good for student projects.
Nice I like this site, im also interested in their software, i found this site which im referencing my friends at uni to Jackaltac - Home page , I dont know what their conditions are I think 5 pcbs per order but we usually to broke to buy more than like 3 ,but they the cheapest iv found so far
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Old 11th March 2011, 10:27 AM   #11003
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I get my boards from OLIMEX Ltd. - Electronic Design and PCB sub-contract assembly OEM/ODM service (see 'protoboards') charging euro 30 per eurocard, double sided incl plating, solder masks & top silk screen. These are professional boards.

jan didden
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Old 11th March 2011, 10:45 AM   #11004
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Quote:
Originally Posted by john curl View Post
Yes, I think so. Bogen, in Germany made the best contoured heads, and they were used on Studer machines. American heads had more ripples. Part of the problem is the WIDTH of the head. Skinny heads are awful!
Hyperbolic heads bad.

Parabolic heads good!

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Old 11th March 2011, 10:51 AM   #11005
gpapag is offline gpapag  Greece
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Quote:
Originally posted by Steve Eddy
I see you emphasized "Losses" in the title, but you overlooked "Windings."
Emphasis was on the "Losses" to make clear that the linked document deals with Eddy Current Losses only, with no hint of inference to Eddy Current Noise.


Quote:
He says absolutely nothing about the core materials, which is what is being discussed here.
Correct, thatís why I didnít include this link to my earlier post http://www.diyaudio.com/forums/analo...ml#post2499291
But reading your:
Quote:
Originally Posted by Steve Eddy
Which means that even a simple length of wire would also exhibit the same frequency dependent "eddy current noise," yes?
I was (and still Iím) under the impression that you were pulling a leg toward the skin effect and proximity effect (which are actually describing the action of eddy currents within the circuitís current conductor own material).
If I failed to read correctly your message, my apologies, but please explain your messageís reasoning.


Quote:
What we're talking about is audio transformers, which are using wires on the order of 42 gauge. With such small diameter wire, skin and proximity effect are effectively non existent at audio frequencies.
I agree that with such thin wires, they are not a realistic problem at audio frequencies. Fig. 15 of linked document verifies this. One more use for the link.


Quote:
And again, it's not the windings that are at issue, but rather the alleged added noise due to eddy current losses in the core.
I am too after this assertion.

Regards
George
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Old 11th March 2011, 11:03 AM   #11006
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This is off topic but there was a terible earthquake and Tzunami in Japan. 8.8 on the Richter scale. I got in contact with Stig indirectly. His family is still in town but Tokio seems to be ok. As far as i know the atomic reactors have being swtiched of.
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Old 11th March 2011, 11:34 AM   #11007
gpapag is offline gpapag  Greece
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8.9 on the Richter scale can not be OT. Thanks Joachim

Quote:
As far as i know the atomic reactors have being switched off.
Japanese were already prepared
Nuclear Power Plants and Earthquakes

Regards
George

http://www-pub.iaea.org/MTCD/publica...ub1158_web.pdf

http://www-pub.iaea.org/mtcd/publica...e_1250_prn.pdf
http://www-pub.iaea.org/MTCD/publica...e_1347_web.pdf
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Old 11th March 2011, 11:41 AM   #11008
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Thats what my sources say. I was surprised too. Maybe it is a typo.
Anyway, it seems to be a desaster.
Attached Images
File Type: gif Richter Scale.gif (11.6 KB, 203 views)
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Old 11th March 2011, 11:55 AM   #11009
DF96 is offline DF96  England
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With regard to eddy current losses, one way to think of these is to add an extra winding to the transformer then put a resistor across the winding. This represents both a loss mechanism, and a source of thermal noise. The thermal noise is present whether there is a signal or not.

However, this might not be a perfect analogy as eddy current losses increase with frequency but a loaded secondary is flat. Perhaps a better analogy would be a loosely coupled secondary, so that the induced voltage rises with frequency but there is only a weak back reaction onto the primary.
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Old 11th March 2011, 12:35 PM   #11010
gpapag is offline gpapag  Greece
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Quote:
Thats what my sources say. I was surprised too. Maybe it is a typo.
It is not a typo (bottom of page)

Latest Earthquakes M5.0+ in the World - Past 7 days

Details:
http://earthquake.usgs.gov/earthquak...11/usc0001xgp/

Glossary of Terms:
http://earthquake.usgs.gov/earthquakes/glossary.php

Regards
George
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Last edited by gpapag; 11th March 2011 at 12:55 PM.
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