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    volts and amps (any electricians?)

    Anyone able to help me?

    I have 4 cctv cameras, at present they are all plugged into individual 12volt 1amp adaptors.
    If I was to buy one adaptor to replace the four, and then hard wire them to that one plug, is it simply 12 volt 4amp that I need - or is there more to it than that?

    15 Comments

    Original Poster

    Yup, thats what I've got all ready.
    Its just a case of knowing what single power supply to plug in the other end

    meispete;4114857

    Yup, thats what I've got all ready.Its just a case of knowing what single … Yup, thats what I've got all ready.Its just a case of knowing what single power supply to plug in the other end



    Well it needs to be 12 volts and supply enough current to supply the cameras (it should tell you the usage)

    Failing that If you cant find the info. We know that Amp x volts = watts. So 4 x 12 = 48 watts but I'm sure they don't require 1 amp each.

    Original Poster

    Definately 1amp each, not following where watts fit into chosing the right mains adapter?

    This will do. You can probably find one a little cheaper if you shop around.

    ]http//ww…578

    GAVINLEWISHUKD;4114884

    This will do. You can probably find one a little cheaper if you shop … This will do. You can probably find one a little cheaper if you shop around.]http://www.maplin.co.uk/Module.aspx?ModuleNo=48517&C=41578



    that will do as the output is approx 4A
    you want to get a 4 amp output if the power consumption of each unit is 1A or there abouts
    also look on the label of the power adapters you are using as it will have more information (polarity)
    make sure you get polarity correct +-

    I would wait till someone with an electrical background comes on to answer your question. :thinking:

    This one is cheap at £6.99, if you can wait for it to be sent from China.
    ]http//ww…tor
    I've never bought from them so can't say if any good.

    Your thinking is correct in the sense 4A will definately be enough, its probably overkill to be honest (are you sure it doesn't say the consumption in watts or amps anywhere else on the camera itself?). If you have a multimeter you could measure what current they are actually drawing from the PSU, then multiply that by 4 and give a little extra headroom, but its safe to say a 12V 4A PSU (like the Maplin one suggested above) should be adequate and safe, provided the cables aren't very long...

    (Power adapters are usually rated in the voltage they provide and the maximum current they can provide hence yours saying 12V, 1A. Power consumption is usually measured in Watts at a specified voltage, although its often not mentioned on DC/battery powered items...)

    As above...

    The rated current on a PSU is that of the maximum it can give out, not what is forced out.

    The cameras will most likely be rated around the 700-800mA, but the manufacturers give a higher rated PSU just in case any extra is required (maybe a surge on powering up).

    So, another yes, you can use a 12VDC 4A PSU.

    The only thing I can advise with CCTV Equipment, consider the length of the DC Cables you intend to use if the cameras have Ir LEDs (Night Vision). There can be a voltage drop if the cables are longer than the ones provided with your equipment and this usually results in the cameras not working at night (as the LEDs pull more current, the voltage drops and doesn't power the camera).

    If you currently have 4x 12vdc 1 amp psu's then just swap the 4 for one of these
    ]http//ww…GBP

    Not the cheapest (much cheaper if you are in the trade) but, keeps everything separately fused so one faulty camera wont take down your entire system.

    V = I x R (Very Important Rabbits)

    P = I x V (Peter Is a Virgin)

    Hmm, i learnt tons of these for my Separates Physics GCSE, but they've all gone out my head now

    I cheat with my electrical devices and wire them all direct to a spare ATX power supply. It's easy to do - a bit of wire between the green and a black of the motherboard power connector will automatically turn the PSU on whenever the AC input is live, and from there, cut the power cables to the cameras apart, crop the molex connectors, and connect the wires so that the positive of your camera's line connects to the yellow, and the negative connects to the black. I could make you a quick photo guide if you want, but it's all very easy and straight forward.

    The neat bonus with using an ATX PSU is that you can power all kinds of things with it. You get a 3.3v output, a 5v output, can make a 7v output, and I think it's possible to make a 17v output out of it too, which should, in theory (although, this isn't something I've yet tested), be capable of powering a laptop.

    dxx;4238085

    I cheat with my electrical devices and wire them all direct to a spare … I cheat with my electrical devices and wire them all direct to a spare ATX power supply. It's easy to do - a bit of wire between the green and a black of the motherboard power connector will automatically turn the PSU on whenever the AC input is live, and from there, cut the power cables to the cameras apart, crop the molex connectors, and connect the wires so that the positive of your camera's line connects to the yellow, and the negative connects to the black. I could make you a quick photo guide if you want, but it's all very easy and straight forward. The neat bonus with using an ATX PSU is that you can power all kinds of things with it. You get a 3.3v output, a 5v output, can make a 7v output, and I think it's possible to make a 17v output out of it too, which should, in theory (although, this isn't something I've yet tested), be capable of powering a laptop.



    Whilst this works, its not really all that advisable - ATX PSUs are designed to give out much higher currents and as such are very inefficient at low power draws so you'll end up paying quite a lot. They also often have a common ground, so the only way to make 17V would be between the -5V rail and the 12V rail; the -5V is rated only for very low currents (not enough to power a laptop!).

    jah128;4239555

    Whilst this works, its not really all that advisable - ATX PSUs are … Whilst this works, its not really all that advisable - ATX PSUs are designed to give out much higher currents and as such are very inefficient at low power draws so you'll end up paying quite a lot. They also often have a common ground, so the only way to make 17V would be between the -5V rail and the 12V rail; the -5V is rated only for very low currents (not enough to power a laptop!).



    Agreed...

    Also, if one of your items connected shorts and PSU pops its cloggs, it could easily take out the other items connected.
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