CCTV power supplies come in a wide assortment. The one needed for any given application is based on the power requirements of the device that needs to be powered. An individual transformer, whether it is AC or DC, is all that is required for one camera. If, however, you have more than one camera to be powered up, than a multi-camera power supply might work out better. If your having trouble selecting the right power supply for you, then please give us a call at (800) 572-3390 or visit the CCTVhelp.com forum for support