ljarrald 0 Posted December 8, 2011 hi, about two weeks ago i added a camera to look at my back gate power and video go through a single cat-5 cable. i used cheap baluns and i had to use an 8 ch PSU because there were no free outputs on my other one, this camera was the only thing connected to this PSU and the picture was fine. but then i added two cameras at the front of the house this weekend (there will eventually be 4 cameras at the front of the house and the video signals from all of them will go through a single cat-5 cable), i have run one 4 core cable to supply power to all 4 cameras (doubled up cores) which is currently powering the two cameras i installed at the weekend. i am, again using baluns for these cameras. when i connected the power cable for the cameras to the 8CH PSU that the back gate camera is connected to, everything seemed fine. but then i connected the blauns at the dvr end and as soon as i plugged one of the new cameras at the front of house in (camera 9), cam 6 (back gate camera) suddenly got interference in the form of horizontal lines (a bit like the 'cctv effect' commonly used in films). when i plugged the second front of house camera into the dvr(camera 12), camera 6's interference stayed the same but there seemed to be a bit of ghosting on cameras 9 and 12. it is a bit hard to explain so i will get a video when i am back home. i have used blauns everywhere else in my system and there seems to be no problem. the blauns i used for the 3 cameras mentioned in this post are slightly different to the ones i've used in the rest of the system, but that shouldn't effect it... should it? Share this post Link to post Share on other sites
Soundy 1 Posted December 8, 2011 99.9% chance it's a ground loop caused by cheap common-ground cameras and shared power supplies. The ways around it are to use dual-voltage cameras or cameras with built-in regulation (ie. cameras that DON'T have a shared power and video ground), or to use a separate power adapter for every camera. Share this post Link to post Share on other sites
ljarrald 0 Posted December 8, 2011 99.9% chance it's a ground loop caused by cheap common-ground cameras and shared power supplies. The ways around it are to use dual-voltage cameras or cameras with built-in regulation (ie. cameras that DON'T have a shared power and video ground), or to use a separate power adapter for every camera. this is what i was thinking, can i get some sort of ground loop isolator? the cameras are not cheap ones. Share this post Link to post Share on other sites
Seedigital 0 Posted December 8, 2011 Yeah, look at SC&T, they do ground loop isolator baluns. They are a pretty standard part, so I assume your local supplier should have them too Share this post Link to post Share on other sites
rory 0 Posted December 8, 2011 how is the video at the camera with a monitor connected to it? your cheapest route would be to power the 2 or 3 new cameras individually, or at least split them up until the problem goes away. some cameras just dont like each other Share this post Link to post Share on other sites
ljarrald 0 Posted December 9, 2011 it is just a home system, as much as i'd like to... i don't have a test monitor would some of these work? do they go at the camera or dvr, or both? thanks! Share this post Link to post Share on other sites
Seedigital 0 Posted December 9, 2011 If its a ground loop issue then yes that will work fine, that's an SC&T in-line ground loop isolator do note that it does lower the video strength a bit so if it gives a weird picture you may need to try adjusting the gains either on the camera and on the software. Also you'll note that it has to go on the camera, then link to the cable these are not bi-directional. Good luck! Share this post Link to post Share on other sites
ljarrald 0 Posted December 9, 2011 If its a ground loop issue then yes that will work fine, that's an SC&T in-line ground loop isolator do note that it does lower the video strength a bit so if it gives a weird picture you may need to try adjusting the gains either on the camera and on the software. Also you'll note that it has to go on the camera, then link to the cable these are not bi-directional. Good luck! so like this then? i would of thought it would need to go at the DVR end :/ Share this post Link to post Share on other sites
Seedigital 0 Posted December 9, 2011 That is correct!, I thought it was the other way first time round, but when you get it you will see that there are some arrows on it showing direction of the signal. If you really want to you could cut off the BNC's and resolder them in the other direction but yeah.... I wouldn't recommend it. Share this post Link to post Share on other sites
Soundy 1 Posted December 9, 2011 Operationally, it shouldn't matter which end of the run you install the isolator - all it does is add some physical separate of the line. Share this post Link to post Share on other sites
ljarrald 0 Posted December 9, 2011 Operationally, it shouldn't matter which end of the run you install the isolator - all it does is add some physical separate of the line. thanks, i think i will add it at the DVR end then Share this post Link to post Share on other sites
rory 0 Posted December 9, 2011 thanks, i think i will add it at the DVR end then Ofcourse that means you have to buy it, and wait for it to come, then hope it fixes the problem. Quick simple solution is to at least test with separate power supplies first, should have some lying around or can get them cheap at any local store. Share this post Link to post Share on other sites
ljarrald 0 Posted December 15, 2011 i have just connected up a microphone to the same cable that the cameras get power from and it seems to of fixed my problem Share this post Link to post Share on other sites
