CCTV camera 12V DC or 24V AC?

[camdvr 0]

I have Extreme CCTV WZ16 compact camera. According to manual it accepts 12V DC or 24V AC. It came with 12V DC power supply. Everything works until I connect 75' CCTV Siamese cable (Power / Video). I have checked power from the other side of the cable and its drops from 12 to 11…11.5 V DC.

 

Is it common thing that the power drops that much at longer cables?

Camera has regular CCTV power socket (2.1mm) which have a polarity. Looks like camera accepts 24V AC but AC doesn’t have any polarity! How technically use that camera with DC power?

Is that possible to use same power socket for 12V DC or 24V AC?

 

What is the better way to deal with that problem?

[griffonsystems 0]

i would go pickup a 4channel 24vac fused power supply from altronix and connect your camera and you will be good. the cheaper way would be to go get a 24vac transformer plugin and connect your camera that way.. i always go with 24vac for power because i like to centralize my powersupplies in the same room as the dvr so when a client calls and says the cameras is out i have them open the altronix power supply and check the fuse and its usually blown and they replace and its back up

 

my2cents

[rapid 0]

How many cameras do you have?

 

If only one, check to make sure the plug in transformer is at least 1 amp as this camera draws alot and depending on distance you will have a voltage drop over long lengths.

 

Most cameras nowadays accept either 12 vdc (polarity) or 24vac (no polarity) and they have internal circuitry which compensates.

 

If you have more than one camera, I'd do as Griffon says....buy a 24vac power supply and save power!

[rvella 0]

When dealing with DC, voltage will dissipate much quicker. It's called Ohm's law -- basically the more distance involved, the more resistance, thus more energy loss.

 

There are several Ohm's law calculators out there online that will tell you how many volts you need to push into a wire given a certain distance. The only one I can reference is this power over ethernet one:

 

http://www.gweep.net/~sfoskett/tech/poecalc.html

 

That will give you an estimate for 22 guage wire at minimum.

[Metal Shaper Man 0]

Altronix also has charts and tools to work with.

 

http://www.altronix.com/index.php?pid=4

[kensplace 0]

dc and ac should both loose volts the same, unless Im missing something..

 

AC just suffers less in cctv as ac is almost always 24v, and dc 12 - so dc is less to start with.

 

Combine that with the fact that DC cams that require 12v often actually require 12v (or close, maybe they feed a 9v reg, so 11 would work, depends on the cam) whereas 24v cams have lots of headroom as they still only need 9v or 12v to operate, and the 24v ac is rectified to dc then fed into a voltage regulator to get the 12v or 9v or whatever the cam needs. As 24 is coming in, there is lots of room to loose voltage via volt drop before a problem is noticed.

 

Plus, 12vdc supplies (good ones anyway) should put out pretty much 12v exactly (or 13.7 i think) for the non regulated ones, but 24v ac ones can easily put out 27 or more volts under a light load, as they are almost always cheaply made, usually nothing more than a box, transformer, fuse, connectors and hefty price tag - they wont have any voltage regulation, and the voltage they supply will vary according to the load connected - unlike a regulated 12v supply, which sticks at 12v

[galen 0]

CamDVR, I agree with everything said here, but one thing you want to remember is that, the WZ16 has 18 LED's that are going to suck power. Its OK to use the 12 volts on a short connection but for the long runs, that's why the manuf. builds in both. I always use the 24V source for over 150 feet with cam's with a fair amount of LED's. (Day/night cams) Hope this helps.

[Oxide.Blu 0]

When using a voltage drop calculator remember to include both the path to the camera and the path returning from the camera. So on a 75-ft run of Siamese cable the length to calculate for is 150-ft.

 

Kensplace – it doesn’t work quite like that. DC voltage drops off a lot faster, can be an issue inside of a 10-ft run for some things. AC voltage drop usually doesn’t start to become an issue until you get into cables that run several hundred feet. To give you some idea, look at the distance from the transformer nearest your home to the furthest wall receptacle in the back of your house.

 

DC voltage drop can be worse in the summer depending on where the cable is run. If it is run thru an attic without proper ventilation the increased heat can cause the voltage to drop, too. When I do boat wiring I need to calculate how may feet of wire ran thru an engine compartment and calculate a separate voltage drop at a higher rate for that part of the cable run.

 

I am surprised the camera is not working with 11.5vdc. That’s only around a 4% drop in voltage.

[kenocurry 0]

good day everyone can someone please help me i have a kmoon dvr cctv system i have a 24v adapter on it the adapter do not tell me if it's ac or dc onto the cam when i cut it on after a minute or to it starts blinking slow and then fast it stays like this could the power be the problem just buy it brand new thanks

[videobruce 0]

24v should be AC. Are their polarity making on the terminals?