When we use a TVI or CVI technology, you can get resolutions of 5 megapixels or 4K. These technologies use a Siamese wire. Siamese wire transport power to the camera and returns signal for the DVR. To power the cameras, a 12 volts power supply is commonly use, but have disadvantage in a long wire installation. Voltage drop is the main concern in a long wire installation and occurs when the voltage at the end of a run of cable is lower than the voltage at the Power supply. Long length of wire will have noticeable resistance, and running a current through this dc resistance will cause the voltage to drop, and camera malfunction. The cameras are design to work with 12 VCD, some kind of cameras can be power from 11.5 volts to 13.5 volts without damage the camera. If you use an adjustable power supply and you have run a wire for more than 300 feet’s, the voltage drop can be compensated adjusting the voltage to more than 12 volts, in this way the camera will have the right voltage to work, the cameras that are closer to the power supply will have more voltage, but there is no problem if you use the right camera than accept more than 12 VCD without damage it.