Extend USB cable for webcam

Discussion in 'General Electronics Chat' started by timdiy, Feb 7, 2012.

  1. timdiy

    Thread Starter New Member

    Jul 1, 2011

    I'm trying to extend USB cable to power webcam for security reasons - I need the webcam to be far away from a computer. I know there are USB extender I can buy but I m trying to do it myself if possible.

    My experiment so far have yielded the following results and would like to get feedback on them. Basically due to the length of cable the extension would only work for low-intel devices like keyboard/mice but not for webcam and USB drives. From Ubuntu /var/log/syslog I can see unstable connection to the device on and off, one minute the webcam is connected but then it drops off...etc. So what is a way to extend the USB cable so it can power high-intel devices like webcam ?

    NOTE : I don't believe the problem is the voltage drop due to cable length since I measured the volts at far end of the extension and it comes out to 5+ volts for USB red wire.

    Extend with 2 or more USB cables
    CONNECTION : each USB cable is roughly 5 ft long
    RESULT : webcam can only be connected properly with less than 2 USB cables, with 3 cables the device would connect on and off.

    Extend with traditional phone line
    CONNECTION : phone line has 4 wires so I simply connect them to USB cable's 4 wires. Phone line is roughly 25 ft.
    RESULT : webcam would connect and drop off...etc

    Extend with CAT5e - connection 1
    CONNECTION : CAT5e has 4 pairs of twisted wires. I connect each pair to one USB wire. CAT5e cable is roughly 25 ft.
    RESULT : webcam would connect and drop off...etc

    Extend with CAT5e - connection 2
    CONNECTION : I give USB red(+5) and USB black(ground) 1.5 pairs of CAT5e twisted wires each and only 1 wire for USB D- and D+. So from the 8 total wires out from the CAT5e, 3 wires goto USB red, 3 wires goto USB black, 1 wire goes to USB D+ and 1 wire goes to USB D-
    RESULT : webcam would connect and drop off...etc

  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    Basically..You don't extend the cable as then you violate the standards published acceptable delays,etc.. and the USB stops functioning properly as you have found.
    I seem to remember something about a 5meter max length for USB and I'm sure there is a max allowed delay.

    What you should do is #1 either purchase the proper webcam (like one with an ethernet port or wifi other longer distance cabling solution)

    Or you convert from USB to another form of long distance cabling solution. I'm sure there are tons of USB to ethernet or USB to fiber or USB to whatever adapters out there for this exact situation.
    But you need a solution thats not just splicing a different cable inline.. It needs to switch/boost/convert the signal to a suitable format then probably back to USB again so your webcam program will see it.

    But in general you are trying to get a "cheap" solution to work when a "more expensive" solution is required.