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The Cat 5 specification calls for under 0.188 Ohms/meter for a loop (down and back). A 50 foot run is around 15 meters, so that is 2.82 Ohms. At 300 MA, that will result in a voltage drop of about 0.85 V, yielding about 11 VDC at the camera, probably within the units operating range. You could compensate by using a 13.4 VDC battery elimator type wall wart.
There is a specification for providing Power over Ethernet (PoE), but that calls for a nominal 48 VDC at 350 MA maximum and would only work if the cameras are Ethernet devices.
Most web cams are USB devices, with 5 VDC at 500 MA provided as part of the USB specificaion. Howver, 50 feet is too far for the USB specification, which limits the length to 5 meters (16 feet).
If these webcams are actually video devices, then now you have an impedance mis-match, video cable being 75 Ohms unbalanced shelded and Cat 5 being 100 Ohms balanced unshieded.
What are the specifics?
posted by 169.253.1...
Posts in this Thread:
- electronics question (amperage, etc.), Mike, Thu, 12 Jan 2012 13:06:13
- Re: electronics question (amperage, etc.), Dean, Fri, 13 Jan 2012 06:45:26
- Re: electronics question (amperage, etc.), TML , Thu, 12 Jan 2012 14:56:44
- Re: electronics question (amperage, etc.), Mike, Thu, 12 Jan 2012 15:23:48
- Re: electronics question (amperage, etc.), TML , Fri, 13 Jan 2012 03:50:45
- Voltage drop, Gene N , Fri, 13 Jan 2012 06:49:26 <-- Viewing This Message
- specifics, Mike, Fri, 13 Jan 2012 13:17:18
- Re: specifics, Gene N , Fri, 13 Jan 2012 16:49:03
- wire, nwas, Fri, 13 Jan 2012 15:21:46
- half wave, nwas, Fri, 13 Jan 2012 11:17:34
- don't do design by test., James, Thu, 12 Jan 2012 18:51:07
- Re: Web cam current, BobS, Thu, 12 Jan 2012 13:19:07
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