I have successfully installed a number of video
surveillance cameras up to 1200 feet from the monitor/power
supply using CAT-5 twisted-pair wire.
suppliers offer small adapter units to place at
each end of the CAT-5 cable to feed DC to the camera
and receive video back to the monitor. Check out
. The main problem with
CAT-5 is that its' DC resistance is approximately
30 ohms/1000 feet. This means that there is 30 ohms
in the DC feed wire going TO the camera and 30 ohms
in the DC return.
It is possible to modify
the adaptor modules so that spare pairs of wire
are paralleled in order to cut the resistance in
I solved the problem of excessive voltage
drop by using a power supply with a higher voltage
output and installing a simple little 3-terminal
regulator at the camera to drop any excessive voltage
back down to the required 12VDC. Whatever you do,
calculate the voltage drop based on the total resistance
in your CAT-5 run and use a power supply that puts
out 5 to 8 volts above that and let the 3-terminal
regulator drop the voltage at the camera site back
down to the required level.
The video coming
back from a 1200 foot run of CAT-5 cable is just
a tad soft from high-frequency roll-off, but is
still at least as sharp as a the video playback
from a typical VHS video tape cassette player.