Making a 20ft long USB extension cable!

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Weaksauce
Joined
Jul 13, 2006
Messages
89
Hi guyz
I needed a number of 20ft long usb extension cable.it wasn't availabe in my town so i decided to make one and give it a try.i got a normal 2ft one and cutted it half. i got a 20ft cable that contains 4cables in it and just connected the 4 wires at the 2 ends of USB cables. I simply scratched the thin wires and folded them with the corresponding cable and then covered by scotch tape so that none of them gets short with eachother.
Now the problem is that when i connects something to the other end then computer doesn't recognizes the USB device. Though it detects that a USB device got connected.

What could be the reason. Do i need to solder the cable joints .Will it fix the problem?
 
Maybe but it is a crapshoot. Soldering would help the signal get thru better but I doubt it is enough. How about ordering some?
 
I have not built a 20 foot USB extension so I'm probably talking out my ass, but I have been working as a hardware design engineer for almost 30 years so here's my suggestion...

A USB cable has four wires red/black (power) and white/green (data). For a run over 20 feet, the white/green need to be a twisted pair, but wire size doesn't matter much.

Next if the PC (or a hub) is providing power to the USB device, it is important that the wire size is large enough to supply 5 volts over the red/black wires without too much voltage loss. For 20 feet and 500 mA current you should use 22 awg wire or larger.

The wiring (at least over the data pair) needs to be shielded and grounded on both ends.
 
A while back while searching for a 50 foot USB cable, I ran across something that said the USB spec doesn't allow for cables longer than either 14 or 16 feet without being amplified.
 
20 feet is going to be borderline, USB spec is 5 meters, just over 15 feet. I really suggest you get a powered hub and put in the middle of two 5 meter cables. You should be able to find 5m cables no problem.

USB device troubleshooter..Read the damn spec so many times.
 
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