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Old 30th May 2012, 06:08 PM   #23531
SY is offline SY  United States
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Morgan verified that the noise added by power. He got a bit of excess noise which he attributed to a questionable solder joint. And yes, the result will be an average.
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Old 30th May 2012, 06:09 PM   #23532
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Originally Posted by jneutron View Post
I purchased 1000 feet of mike cable from parts express, and pull the braid off as I need it.
What do you do with the rest of the cable bits?

se
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Old 30th May 2012, 06:14 PM   #23533
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Old 30th May 2012, 06:16 PM   #23534
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Morgan verified that the noise added by power. He got a bit of excess noise which he attributed to a questionable solder joint. And yes, the result will be an average.
I would consider an unverified bad solder joint explanation sloppy work. It might hide something interesting.

As is I assume obvious, the higher the current the lower the dynamic resistance and the lower the noise.
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Old 30th May 2012, 06:24 PM   #23535
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Or it could be a sloppy solder joint. It made very little difference to the predicted outcome, but Morgan likes everything nice and tidy, so a few percent difference bothers him more than it does me. You can read about it when the new edition of his book FINALLY appears. I just seriesed them, took the spectrum, divided by sqrt n, and called it a day- 0.4nV/rt Hz is way and away quiet enough.
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Old 30th May 2012, 06:24 PM   #23536
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Or Mouser, or DigiKey, or...

But to buy 1,000 feet of microphone cable in order to scavenge the shield?

I hope there's more to the story.

se
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Old 30th May 2012, 06:29 PM   #23537
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I did have a video guy once try to spec audio wiring. He wanted at least 5" of shielded twisted pair stripped back and covered with heat shrink tubing, using a green piece for the drain lead.

John (N) couldn't have explained it to that guy, not even with pictures.
It would depend on the environment of the audio cable. High fields, high differential pickup. It's not rocket science..

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Actually I thought I had nice diode switching pictures, but when I went to add them to the article I couldn't find them. So on my things to do list is to redo them.
Sorry, can't help you there. I used to do mil trr testing, built a rig to do 250 picosecond falltimes..good for sub nanosec diodes. But that's with a former employer.
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The manufacturer pointed out that noise was not a specified parameter and their diodes did meet all spec.s Of course they did fix their process.
Some product does have speed limit, but in general, they only test for a recovery time maximum.

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So it is the turn ON noise that has more energy than the turn off!
Inductively correct, but that energy is stored at a slew rate defined by the circuit resistance, source impedance, stray capacitances, distance to primary source impedance and the physical inductance of the feed wiring. During turn off, the diode will let go based on it's diffusion profile, recombination site density, sweep speed, local parasitic inductances and capacitances. The coupling to external circuits will depend entirely on the current slew rate, while locally it will be the IR drop effect and dI/dL. Turn on will in general, affect anything attached or very close. Turn off can radiate like a B....

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What do you do with the rest of the cable bits?

se
toss em. I don't need white or blue wire. Magenta perhaps I would keep....

Here's a spool of braid over the core wires...the bass shakers are to precondition the electrons within the grain boundaries..

j
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Last edited by jneutron; 30th May 2012 at 06:36 PM.
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Old 30th May 2012, 06:32 PM   #23538
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Originally Posted by Steve Eddy View Post
Or Mouser, or DigiKey, or...

But to buy 1,000 feet of microphone cable in order to scavenge the shield?

I hope there's more to the story.

se
Oh, you didn't ask about that.

I purchased the spool to run mike's and unbalanced runs for a show in an auditorium. Used about 300 feet for that. Plus about 10 various and assorted mike cables, most about 50 feet.. The rest is on the spool at home...minus of course, what I use for play projects.

j
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Old 30th May 2012, 06:34 PM   #23539
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So Wavey did I cover what you want to reveal to the uninitiated unworthies?
No, I meant inductive pickup of magnetic field by shorted probes.
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Old 30th May 2012, 06:36 PM   #23540
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Originally Posted by jneutron View Post
Oh, you didn't ask about that.

I purchased the spool to run mike's and unbalanced runs for a show in an auditorium. Used about 300 feet for that. Plus about 10 various and assorted mike cables, most about 50 feet.. The rest is on the spool at home...minus of course, what I use for play projects.
Ah, gotcha! I feel much better now. Thanks!

se
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