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weeboludo

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Posts posted by weeboludo

  1. Posted

    Been a while, but thought I'd report back. Went to a store specialising in CCTV systems and They have the following UPS:

    http://www.argseguridad.com/producto_detalle.php?id=459

    With 1 x 4A output, 4 x 1A outputs and claims to run for 5 hours.

     

    The cameras were about 0.5A so I imagine I could connect 2 to each 1A output. The price is equivalent to 200 US or 130 pounds.

     

    They recommended coaxial cable with power cables incorporated, and said using passive baluns that the cables could stretch up to 100m without losing too much signal.

     

    The standalone linux system they have powers up automatically on hard shutdown.

  2. Posted

    Nope, it doesn't work that way, the wattage of the UPS is the peak power it can supply, not for how long.

     

    Take a look at a UPS selector here- http://www.tripplite.com/en/products/ups-system-runtimes.cfm to get a better idea on runtimes. I would just localize power at the DVR, it simplifies things greatly.

     

    As long as the runs are not terribly long, you might want to consider using baluns and CAT5 cable, that way you have everything in one cable, and you could change later to IP cameras (assuming the runs are under 300 feet).

     

    Another choice would be to use Siamese RG59U with 18/2 power wire in the same cable.

     

    Thought I had to be wrong. Cheers for the calculator, unfortunately available equipment here (Argentina) is pretty limited, not sure if any models I see are on this, so I'll have to get my pen & paper out.

     

    Thanks for the advice on cables & wiring ... that was going to be my next post once I understand the backup power requirements and once I have some measurements of the distances.

  3. Posted

    My dvr doesn't like a hard shut down at all, so when there's an outage I can do a soft shut down, in which case having the monitor to see that bit of navigation is helpful.

    If it's a Windows-base DVR, you can install the UPS software that will monitor the UPS status and initiate a proper shutdown automatically when the power gets low.

     

    The idea was a standalone Linux based DVR, running without monitor. There will be power outages, and they will drain the battery completely and there will be noone around to reset it. So .. I'll be wanting somehting with BIOS wake ... wake-on-lan or something.

     

    I'm fairly handy with Linux, so as long as it will wake up and connect to the internet I am happy entering the system myself by SSH and fixing anything by hand. So either wake-on-lan or some BIOS setting. Though maybe I might have to build a system myself rather than buy a standalone (later I'll maybe ask you all for opinions on the models available here to see if you have experiences)

     

    Cheers

  4. Posted

    Taking the 12V, boosting it up to 120V, only to step it back down to 12V for the cameras is extremely wasteful. I'd use a central power supply for the cameras that has its own 12V backup batteries, so when the power is out the cameras just run directly off the batteries. Then you can use a smaller UPS for the DVR (be sure not to run unnecessary things, like the monitor, off the battery side).

     

    Something like this: http://www.enforcer.com.tw/EnforcerVideo/MODEL1_2.htm

     

    Good point, I'll have a look around see if I can find something similar available around here. Cheers

  5. Posted

    Hi, I'm designing my first system for a friend and I will have a few questions I hope you can advise on, but first I wanted to ask about backup power.

     

    The system is DVR & 7-8 external cameras with IR. I had a bash calculating the backup time:

    8 Cameras at 12Vcc 450mA ... 8 * 12 * 0.45 = 50W
From website, the DVR consumes 25W
Total for system: 75W

    Looking for a random example, I found the DirectUPS DP1000 1000VA 600 Watts UPS at more or less US$100 ....

    Does this really mean:

    600 / 75 ( * 0.9 for perfromance) == Around 7 hours

    This is way more than I expected. Have I gone wrong in the calculations??

     

    Creating an entire closed loop power circuit for the cameras seems like alot of work - though I'll have to lay the signal cable anyway.

     

    Any really strong argument for having perhaps 3 smaller UPS rather than 1 big one?

     

    Thanks in advance for any advice

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