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DIY USB cable

post #1 of 53
10/15/09 at 4:53pm
Thread Starter 
Hi All

This is my first post on my new netbook (need to write lots to see if the keyboard is usable )

I am considering making a USB cable to attach my DAC to it as it only needs to be about 6 inches long and no-one seems to sell them that short. I could use starquad, but was wondering about noise/sheilding. Should I just cut the middle out of a cheap cable or is there a bare cable available for this application? I'm not convinced by expensive digital cables, but sheilding seems a good idea.

Any thoughts appreciated
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post #2 of 53
10/15/09 at 5:31pm
Here is the usb 2.0 specification:

http://www.usb.org/developers/docs/usb_20_052709.zip

Enjoy
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post #3 of 53
10/15/09 at 5:34pm
According to the BantamDAC website, the quality of the USB cable is important (so much so that that Beezar sells a specific high quality "shielded" cable). Based on that recommendation I probably wouldn't try to DIY one, myself. But you're certainly welcome to try!

Also, monoprice.com has 1.5' cables for less than a buck. I've used it with my Bantam with no problems.
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post #4 of 53
10/15/09 at 10:24pm
If you want diy (aka cut a stock cable up) you want to get a real long one, say 15ft for $5-10.

DealExtreme: $2.36 USB to Mini 5-Pin Cable (1.3-Meter)


The problem with the short ones is that they are very thin and cant supply power (ive seen them drop from 5.1v down to 4.5v when plugged in). Then just cut to length.


Basically you need these things:
24 gauge for power and at least 28 gauge for signal
twisted pair, not the strait phone cord style (hey looks its a retractable tape version)
foil shielding
braided shielding


Most usb 2.0 cables should work, and id say almost 100% of extension cables would fit the bill
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post #5 of 53
10/15/09 at 10:53pm
Anybody know where to get USB plugs? Type A anyways.

Quote:
Originally Posted by nightanole View Post
Basically you need these things:
24 gauge for power and at least 28 gauge for signal
twisted pair, not the strait phone cord style (hey looks its a retractable tape version)
foil shielding
braided shielding
Don't forget heatshrink! You always need heatshrink.
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post #6 of 53
10/16/09 at 2:59pm
u can buy usb shortys from amazon too .... they sell them cheap and they are decent quality Amazon.com: usb shortys
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post #7 of 53
1/11/10 at 7:04pm
I have read through the salient parts of the USB 2.0 specs and have a question if anyone can answer. Power is easy, as anything between 20awg and 28awg is acceptable. Data is only listed at 28awg as a twisted pair. Besides being technically out of spec, would there be any other negatives to using a slightly lower gauge (26 or 24) for the data?

And on a slight tangent, does it matter which shield goes where? I know the USB spec calls for the wrap shield inside of the braid, but is there any harm in doing it with the wrap outside the braid? This is more a cosmetic thing for me, as the mylar foil I have is very pretty and shiny and I wanted it to show through the clear PVC tubing I was going to use for the outer jacket.

And I have found several sources for nickel plated Type B connectors, but no gold plated ones. Gold plated Type A's I can get from Mouser, but not Type B's (L-com doesn't have them either). I would prefer gold plating, but I will go nickel if I have to simply because I refuse to have a cable that doesn't have matching ends. Anyone know of a source for gold plated Type B connectors?

Ok, I think that is it!
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post #8 of 53
1/11/10 at 7:28pm
I have built a few to experiment, so far I like what I see.

If you don't need to power the device, skip the power lines all together.
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post #9 of 53
1/12/10 at 6:16pm
Quote:
Originally Posted by FraGGleR View Post
Anyone know of a source for gold plated Type B connectors?
I'd like to know as well, I'm itching to put together a few DIY USB cables.
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post #10 of 53
1/12/10 at 6:59pm
Mouser

B : 154-UBW32-E
A : 154-UAW16-E
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post #11 of 53
1/12/10 at 8:32pm
Quote:
Originally Posted by FallenAngel View Post
Mouser

B : 154-UBW32-E
A : 154-UAW16-E
I saw those, but couldn't tell if the shell was gold plated or not. I know the contacts are. Have you used these? I have a Mouser order to put together and I would love to throw these in to save one shipping down the line. Thanks!
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post #12 of 53
1/12/10 at 8:52pm
Yes, I have used them; the shell is not gold plated, just the contacts.
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post #13 of 53
1/12/10 at 10:17pm
Quote:
Originally Posted by FallenAngel View Post
If you don't need to power the device, skip the power lines all together.
and skip groundloops altogether! I'll keep it in mind
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post #14 of 53
1/12/10 at 11:41pm
Quote:
Originally Posted by FallenAngel View Post
Yes, I have used them; the shell is not gold plated, just the contacts.
Cool stuff. Thanks for sharing the pic. What kind of materials did you use? Did you stay in spec with 28awg data?
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post #15 of 53
1/13/10 at 6:42pm
Quote:
Originally Posted by FallenAngel View Post
B : 154-UBW32-E
A : 154-UAW16-E
Thanks Pavel. I'm going to put a couple together and compare to the Kimber USB cable.
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