The VDB775 is meant as a replacement. The power requirement for AC transformer is 16-24 VAC, 10-40VA (16VAC, 10VA recommended). Your transformer should state what its rated for. Similarly, the 770 is AC transformer 16-30V AC, 10-30VA
More information on the 775 including installation instructions can be found below. While we do not currently carry this camera, we should have it available on the store front soon. Otherwise, compatible equipment can be purchased elsewhere and still be used with service.