John Curl's Blowtorch preamplifier part II

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#9,281
jneutron said:
The braid picture you provided has the outer braid tight. As the wire bundle is constricted, longer wires are extruded axially like a tube of toothpaste. Eventually, the buildup is enough to pop some strands sideways. Is the pop-out bundle consistent with 11 strands or 33?
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In the case of the blow-out, we're basically talking about the whole wire bundle. See the second wire from the top in the first photo.

se
 
#9,282
stinius said:
When I'm reading the description of how you make the cable and looking at the pictures, I think that the result is as expected.
I think there are two different ways to solve the problem, if you’re interested, send me a PM with your email address and I’ll let you know.
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Thanks! PM on its way shortly.

BTW: English is my second language. 🙂
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I'll keep that in mind. 😀

se
 
#9,290
Steve Eddy said:
Yes.

And of course before the Mr. Coffee machines hit the scene, we used percolators which kept running the coffee through the grounds. 😱

se
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That's not entirely true. If you were in the know, you could have used a Chemex. My mom still has one she bought in NYC in the 50's. Inexplicably, though, she ran Medaglia D'Oro through a percolator all the years I was growing up 😀
 
#9,296
Quotes from Post #9280 SE

That's gotta be a mechanical process.
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I agree. 99.9 % is a mechanical process issue.
The stresses seem too high to be caused by electrical repelling forces.
I intervened just for this 0.1 % (smartass too ).

Well, cotton is one of the most neutral materials on the triboelectric scale, and even if it weren't, I can't see how it could possibly cause the mangling of the litz as shown in the photo.
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For untreated cotton , this is correct. But cotton fabric may have received some chemical finishing processes which would alter it’s triboelectric behaviour.
In any case, it has to be checked with regard to the other materials that it rubs against.

Electrostatic force induced phenomena are to be investigated closely after all other possible issues have been cleared out, for it is very tricky to spot them.
Just one slightly changed parameter in the process itself or of materials involved -especially on high speed run processes- and things are not the same as with “yesterday’s run”.

Happy Birthday Scott Wurcer

Regards
George

Note. In textile industry, they use to “anneal” the uneven (mechanical) stresses of cotton fabrics with a process called Sanforization
Sanforization - Wikipedia, the free encyclopedia
 
#9,297
Steve Eddy said:
In the case of the blow-out, we're basically talking about the whole wire bundle. See the second wire from the top in the first photo.

se
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I was speaking only of the obviously braided last two pics.

I am confused by the top pics you refer to. It doesn't look like a braid, but a spiral wrap. If it is a spiral, the torque is transferring to the litz and it eventually pops it's stability. The litz wire is acting exactly like the rubber band in a band airplane where the twists knot up. I'd increase the litz tension, and bring the payout roller pair (pinch the litz with high compliance elastomer) right up to the braid/spiral contact point to stop allowing litz rotation to the payout spool, and I'd do the exact same thing above contact to prevent twisting above contact. The process should not buildup twist to pop the litz as it is doing.

Cheers, John
 
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