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Building an Audio Circuit...
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Clinically Insane
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A really simple circuit. Like, three resistors.
Normally, I'd take my time and do it right, refresh my skills at soldering, build offsets in the project box, etc., but I'm in a bit of a hurry.
My plan is to wire it on some perfboard. Twist the leads, see if it works, and if it does, cram the project box full of non-conductive epoxy.
The key here is it needs to be bulletproof. It's going to be used in the field, and I can't have it die from a bad joint or a poorly engineered strain relief.
Is there anything I'm missing here? Is this a bad idea?
In my favor, it's for digital audio, so the signal doesn't need to be audiophile clean, I just need the bits to get through.
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Clinically Insane
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Writing it out makes me realize I can probably lose the perfboard.
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Posting Junkie
Join Date: Mar 2004
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Soldering has to be better than just twisting the wires together.
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I have plenty of more important things to do, if only I could bring myself to do them....
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Professional Poster
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They make conductive glue too. I doubt it's a really good conductor though.
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Clinically Insane
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Originally Posted by Waragainstsleep
Soldering has to be better than just twisting the wires together.
It's not just twisting them, it's twisting them and then packing it with epoxy.
The only way I can see solder being better is were I to need to desolder it. The only reason I can think of for that would be replacing a blown resistor, which A, won't happen, and B, I can just rebuild the whole thing anyway.
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Posting Junkie
Join Date: Mar 2004
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Originally Posted by subego
It's not just twisting them, it's twisting them and then packing it with epoxy.
The only way I can see solder being better is were I to need to desolder it. The only reason I can think of for that would be replacing a blown resistor, which A, won't happen, and B, I can just rebuild the whole thing anyway.
If you want bullet proof, I'd twist and solder.
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I have plenty of more important things to do, if only I could bring myself to do them....
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Clinically Insane
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Fair enough, but is there some mechanism by which you can imagine them untwisting themselves once buried in epoxy?
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Clinically Insane
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Originally Posted by Waragainstsleep
If you want bullet proof, I'd twist and solder.
FTW.
-t
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Twisted wire is nowhere near as good a connection electrically as a soldered connection. Twist away THEN solder - it shouldn't take much - and you'll have a truly bulletproof connection.
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Glenn -----OTR/L, MOT, Tx
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Clinically Insane
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Okay, okay. Jeez.
Thanks all!
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Join Date: Jun 2000
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How literal are you about the 'bulletproof' part? Soldering is good of course, but perhaps we should be talking about the project box more. Soldered wire in an ordinary plastic box will do exactly squat to stop a .22, much less a .306. A double layer of lucite with kevlar in between would be a better bet.
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Clinically Insane
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Well, I have three project boxes. One is made of straw, one is made of sticks, one is made of magnesium.
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Administrator
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You need titanium to stop serious rounds. Best if you make it by molecular deposition, since you can make the box around your circuit that way. Of course you'll never be able to change out any of the components with this method, but it's still going to laugh off high powered rifle bullets.
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Glenn -----OTR/L, MOT, Tx
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All the guys I know swear by sodium. It the next big thing in armor plating.
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Addicted to MacNN
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Encase it in reactive armor. And for what it's worth, I think twisting the leads will work fine provided you get a good length of contact.
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Posting Junkie
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Originally Posted by BLAZE_MkIV
All the guys I know swear by sodium. It the next big thing in armor plating.
You're kidding right?
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I have plenty of more important things to do, if only I could bring myself to do them....
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Professional Poster
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My DM had a great trap back in the day, it was a priceless marble statue of a goddess, in a cave, behind a waterfall.
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Clinically Insane
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Didn't James Bond have a sodium watch acting as a concealable explosive?
Or was that The Man From U.N.C.L.E.?
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Clinically Insane
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There was a gal at the local hot dog shack that would always ask "sodium on your fries?"
One time I answered "sure, but put some chlorine in there too, I don't want my taters to explode."
She looked at me like I had just killed her dog.
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Clinically Insane
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Originally Posted by subego
She looked at me like I had just killed her dog.
Wait, now I'm confused. I thought SHE was servings the dogs.
-t
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Clinically Insane
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Let's all pretend I'm posting the Korean twentysomething dog barbecue pic.
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Breadboard, twist wires, and wire cap. Done.
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Bush Tax Cuts == Job Killer
June 2001: 132,047,000 employed
June 2003: 129,839,000 employed
2.21 million jobs were LOST after 2 years of Bush Tax Cuts.
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Clinically Insane
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Only time will tell it this was a bad idea, but I went with wire nuts.
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Administrator
Join Date: Apr 2001
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Wire nuts is better than just twisting the wires together. If you make another one, solder it and see if you find a difference in function or longevity.
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Glenn -----OTR/L, MOT, Tx
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Clinically Insane
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Logically, I can't see how wire nuts could be possibly any better than twisting & soldering for low voltage / power applications.
I never thought of wire nuts as a professional tool. They seem to be a US centric thing, I have never seen them in Europe.
In German speaking coutnries, they use this:
http://de.wikipedia.org/wiki/L%C3%BCsterklemme
-t
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Clinically Insane
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Originally Posted by ghporter
Wire nuts is better than just twisting the wires together. If you make another one, solder it and see if you find a difference in function or longevity.
Exactly my plan.
I'm not 100% comfortable with this build. The leads from the resistors are hair thin, and I'm worried twisting on the nut where the three resistors met stressed the leads to near their breaking point.
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Clinically Insane
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Originally Posted by subego
Well, I have three project boxes. One is made of straw, one is made of sticks, one is made of magnesium.
Are you expecting a wolf?
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"…I contend that we are both atheists. I just believe in one fewer god than
you do. When you understand why you dismiss all the other possible gods,
you will understand why I dismiss yours." - Stephen F. Roberts
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Clinically Insane
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Originally Posted by subego
Only time will tell it this was a bad idea, but I went with wire nuts.
I had to look up wire nuts.
Oh boy, you'd get laughed out of a job over here for using those. I got laughed at for using a "Lüsterklemme" (what turtle linked to above) for an audio connection (on solder-covered wire ends), which actually works quite well.
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Clinically Insane
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Wire nuts still confound me. Wires go in, become twisty. Can't explain that.
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"…I contend that we are both atheists. I just believe in one fewer god than
you do. When you understand why you dismiss all the other possible gods,
you will understand why I dismiss yours." - Stephen F. Roberts
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Clinically Insane
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The trick is on the non-crap ones there's a spiral of wire inside which grabs and increases your contact area. The other big reason is re-work but that's not important in this case.
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Clinically Insane
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Originally Posted by Spheric Harlot
I had to look up wire nuts.
Oh boy, you'd get laughed out of a job over here for using those. I got laughed at for using a "Lüsterklemme" (what turtle linked to above) for an audio connection (on solder-covered wire ends), which actually works quite well.
You'd have to know I'd used them:
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Clinically Insane
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Originally Posted by turtle777
Logically, I can't see how wire nuts could be possibly any better than twisting & soldering for low voltage / power applications.
Rusty soldering skills.
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Originally Posted by subego
I'm not 100% comfortable with this build. The leads from the resistors are hair thin, and I'm worried twisting on the nut where the three resistors met stressed the leads to near their breaking point.
Rightly so. Wire nuts are NOT meant for low voltage electronic applications.
Their use is in high voltage / hihg power wiring (like 110V in a home.)
-t
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Clinically Insane
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Originally Posted by Spheric Harlot
Oh boy, you'd get laughed out of a job over here for using those. I got laughed at for using a "Lüsterklemme" (what turtle linked to above) for an audio connection (on solder-covered wire ends), which actually works quite well.
In the same way, Lüsterklemmen are not meant to be used for low voltage electronic application (such as audio). Soldering is.
And yes, Lüsterklemmen can work well in establishing a reliable electronic connection (better than wire nuts), as long as shielding is not a concern.
-t
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Originally Posted by turtle777
Rightly so. Wire nuts are NOT meant for low voltage electronic applications.
Their use is in high voltage / hihg power wiring (like 110V in a home.)
-t
Meh.
They make them way smaller than you could ever use for AC.
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Originally Posted by subego
They make them way smaller than you could ever use for AC.
That doesn't make it right and a good tool/connection.
After reading this, I conclude that the appropriate alternative to soldering is crimping:
solder vs wire nuts - DIYMA.com - Scientific Car Audio - Truth in Sound Quality
The issues with wire nuts are manifold. Oxidation and vibration are some of the ones you might encounter in your application.
-t
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Clinically Insane
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Originally Posted by turtle777
I'm not arguing solder would be worse, however this article makes the exact points which led me to using the wire nuts.
1) They're fine if you have the space and don't expect a lot of vibration.
2) They act as insulators.
3) They act as a strain relief.
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Clinically Insane
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Originally Posted by turtle777
As I said, I wouldn't mind rebuilding it "properly" with solder.
As I also said, this is for digital audio. The quality of the connection is irrelevant as long as the bits get through.
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Every bit has its limits. A poor connection (high resistance) might kill the bit.
-t
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Originally Posted by turtle777
Every bit has its limits. A poor connection (high resistance) might kill the bit.
-t
Hence my desire to rebuild it.
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Clinically Insane
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Originally Posted by subego
As I also said, this is for digital audio. The quality of the connection is irrelevant as long as the bits get through.
On the contrary.
Bad connections can at worst introduce either drop-outs/errors, but invariably cause jitter.
If this is within a circuit that stays digital (i.e. leads to a digital interface that will then re-clock the signal anyway), then jitter is irrelevant.
If the circuit carries a digital audio signal that is used to clock a DAC, then bad connections will result in audible degradation due to reflections within the cable leading to clock jitter (especially if the leads themselves are too short).
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Clinically Insane
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I also wouldn't mind using resistors rated for more that a 1/4 watt too, just so the leads aren't so wimpy.
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Originally Posted by Spheric Harlot
On the contrary.
Bad connections can at worst introduce either drop-outs/errors, but invariably cause jitter.
If this is within a circuit that stays digital (i.e. leads to a digital interface that will then re-clock the signal anyway), then jitter is irrelevant.
If the circuit carries a digital audio signal that is used to clock a DAC, then bad connections will result in audible degradation due to reflections within the cable leading to clock jitter (especially if the leads themselves are too short).
Digital to digital. My mixer is AES out and my recorder is S/PDIF in. This drops the voltage from 3.3v to 1v.
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Administrator
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Wire nuts hold wires together, in contact, quite well, But the only contact between those wires is where they touch each other and the metal liner of the wire nut. Solder, on the other hand, provides a much larger contact surface encompassing the entire surface of both connected wires. Further, a soldered connection can be smaller and less bulky. And soldering forms a chemical bond between the solder and the included wires, making the connection both more efficient and more physically secure.
Wire nuts are for power connections, and they work great for those, where they're appropriate. For a signal connection, a better choice is always solder. With a caveat: if your soldering ethic is "the bigger the blob, the better the job," go with wire nuts-at least those won't fail the way a bad solder joint will. Of course since it really is quicker, simpler and easier to make a good solder joint than a horrible one, I have to wonder why so many bad joints get made in the first place.
And I'll echo Spheric's statement on digital connections. A bad connection may "let the bits get through," but it will also let other stuff get through. Further, with a digital circuit, excessively long leads are a problem because they can pick up stray signals. Digital circuits work best with minimal lead length outside what is necessary for the circuit. The higher the bit rate, the more important minimizing extraneous lead length is.
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Glenn -----OTR/L, MOT, Tx
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Clinically Insane
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:guffaw:
In the time it's taken to argue about how crap wire nuts are I could have soldered half a loom.
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Been inclined to wander... off the beaten track.
That's where there's thunder... and the wind shouts back.
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Clinically Insane
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Originally Posted by subego
Digital to digital. My mixer is AES out and my recorder is S/PDIF in. This drops the voltage from 3.3v to 1v.
Don't forget the silicon to rewrite all the control words.
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Been inclined to wander... off the beaten track.
That's where there's thunder... and the wind shouts back.
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Clinically Insane
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Originally Posted by ghporter
And I'll echo Spheric's statement on digital connections. A bad connection may "let the bits get through," but it will also let other stuff get through. Further, with a digital circuit, excessively long leads are a problem because they can pick up stray signals. Digital circuits work best with minimal lead length outside what is necessary for the circuit. The higher the bit rate, the more important minimizing extraneous lead length is.
If you're going to use cables with plugs, anything shorter than about one meter will introduce extraneous jitter.
Not important if the signal is going to be re-clocked on the receiving end, anyway, but if you're going to a signal-clocked DAC, audible deterioration.
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