Webcam to USB 3.0 to cat 6 to 3.0 to Galaxy S9

[seamusdkporter]

want to take an old webcam and attached it to a semi-ridgid piece of wire/pipe/tubing and run a wire the full length and view the live image on my phone. My research says usb 2.0 won't have enough power to reach 100 ft. But usb 3.0 will. A 100 ft of usb 3.0 is pretty expensive. But it says ethernet cat6 can handle the videos transmission also..cat6 at 100ft is pretty cheap. So can I run bare wire usb from webcam and solder it to bare wire usb 3.0 to male type c - to female to female type c - male type c to male cat6 - to cat6 cable - to female cat 6 to male type c- to samsung S9?

 

[Harald Kapp]

You are mixing up a few things. USB 2 and USB 3 both have a 5 V power line. USB 3 can negotiate for higher voltages, but that will take some active electronics on both sides. So power is not the primary issue.
Contrary to what you assume USB 3 is defined for even shorter ranges (1-2 m) than USB 2 (5 m).

Ethernet is not suitable for power supply per se. There are ways to transmit power over Ethernet (POE), but that again requires expensive electronics on both ends. Plus the conversion from USB to Ethernet and back.

Anyway, your old webcam probably has USB 2 only, so converting to either USB 3 or Ethernet will require additional electronics.
The length limitation of USB is not so much about the power that can be transmitted but about the fidelity of the signal. The longer the cable, the more distortion is introduced and the higher the risk that no stable data connection can be established. For your 30 m you will need an active extension.