ir issues

[flogbags 0]

Hi all,

I have just installed a dvr with 8 cameras, at my fathers, in the day time all the cameras are perfect, apart from 1 having a jittering line on the screen at the top of the picture. Then at night is where all the issues start, 4 of the cameras are fine, but the other 4, is another story. The 2 at the back which are on 40m cables, its like the ir's are only half working, as the picture is black, the other 2 at the front are working day and night, but its as if it is snowing at night. Any help would be much appreciated.

Regards Mick

[cctvmann 0]

sounds like there isnt enough current being given by power supply, you may have to put an additional power supply in one front end and one back end what amperage power supply have you used

[flogbags 0]

Thanx for a speedy reply, would you be able to suggest a power supply, that would take care of these

[cctvmann 0]

what size power supply you using at moment ?

[flogbags 0]

Input 100-240volt 0.6amp

output 12v - 5amp

[cctvmann 0]

id suggest running 2 power supplies and putting half cameras on 1 5 amp psu and half the cameras on the other

[flogbags 0]

Ok I will try that this weekend coming and let you know cheers

[cctvmann 0]

this is how i setup ours, the top psu is 1 12 vdc 10 amp power supply and the lower one is a 10 amp also but top one runs 7 geneie vandal domes (none ir) 1 bullet varifocal camera (none ir ) mounted in lampost covertly) and pirs to make speed domes turn to several areas the lower psu runs the 4 x ir mini speed domes outside.

[Numb-nuts 1]

While amps are important, they are NOT so important as the resulting volts at the camera.

Using a voltage drop calculator might help you discover what voltage you are getting at the cameras in question.

Cameras usually tolerate a drop of no more than 10% i.e. 1.2 volts. which frankly is just at the edge of their requirement.

You can tackle this in a number of ways, my preferred way is to use a 24Volt AC power supply and transform it down to 12v DC this way you are assured of the ideal voltage reaching the camera. Another way is to back-calculate the voltage required to result in 12v at the camera. Fine in theory but there are NOT an infinite range of regulated power supplies available so unless you can get hold of a variable output PSU it's not practical or economically viable.

 

Volts drop off over distance, amps do not. One reason manufacturers often quote watts as the power requirement.

 

Of course if you have mains power more local to the cameras you can take power more locally and transform it down to result in a better voltage. This has been done before and is regularly carried out with good results for the amateur installer.

 

Why do they always put those locks in PSU cases? I've never seen anyone lock them, the keys are there always.

[cctvmann 0]

While amps are important, they are NOT so important as the resulting volts at the camera.

Using a voltage drop calculator might help you discover what voltage you are getting at the cameras in question.

Cameras usually tolerate a drop of no more than 10% i.e. 1.2 volts. which frankly is just at the edge of their requirement.

You can tackle this in a number of ways, my preferred way is to use a 24Volt AC power supply and transform it down to 12v DC this way you are assured of the ideal voltage reaching the camera. Another way is to back-calculate the voltage required to result in 12v at the camera. Fine in theory but there are NOT an infinite range of regulated power supplies available so unless you can get hold of a variable output PSU it's not practical or economically viable.

 

Volts drop off over distance, amps do not. One reason manufacturers often quote watts as the power requirement.

 

Of course if you have mains power more local to the cameras you can take power more locally and transform it down to result in a better voltage. This has been done before and is regularly carried out with good results for the amateur installer.

 

Why do they always put those locks in PSU cases? I've never seen anyone lock them, the keys are there always.

i dont know to be honest, as ive always left keys in the locks above the ceilings myself.