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CCTV cameras: single PSU or individual PSUs ?

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    #21
    Re: CCTV cameras: single PSU or individual PSUs ?

    Originally posted by Dannyx View Post
    Most notably, there seem to be vertical "hum bars" on some of them and some even flash white speckles every now and then.
    Check grounds.

    It could be the new power boxes we installed, combined with the relatively long cable runs which carry 4 video signals at once (one on each pair)...we usually don't do it like this (we run individual cables for each camera), but the system was already in place so we had to use it, as it was too expensive/difficult to run new wires.
    Easy to test that theory: temporarily replace long cables with shorter ones, shared power supply with individual ones, etc. You may discover the cables are routed too close to an RFI/EMI noise source. Or, any Ir emitters in the camera(s) are pulling down the supply when they switch on, etc.

    [I had a camera that kept wanting to cycle between day and night modes. Each transition put a drag on the power supply that the flimsy wiring couldn't accommodate (without additional local bypass AT the camera).]

    Knowing the possible cause of your problem(s) is the first step towards creating a workable remedy.

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      #22
      Re: CCTV cameras: single PSU or individual PSUs ?

      I think the ground is fine...at least the way I see it and there's no better way to do it given the current setup: there's two power supplies, one running 6 cameras on one side of the complex, the other running 9 cameras on the opposite end of the complex, though I forgot if the symptoms were particularly worse on one sector or if they happened on both. Power is fed through several "lamp cords" (though there's probably some cool technical term for it that I don't know right now) which run in separate "legs". Depending on how the cameras are laid out, to cut down on the individual cable runs, they daisy-chained this lamp cord to run 2-3 cameras. The same story holds true for the other box and the FTP cable that carries the video signal: so as not to run an individual cable to each camera, they ran a single length of wire all around and spliced into a separate pair at each camera, so 4 cameras per FTP run. The BNC output of the cameras go into bal-uns which turns it into FTP which then terminates in another bal-un at the DVR end of course...the bal-uns could also make a difference here, although they claim to be Hikvision, just like the rest of the system, not that it would matter, so they seem decent in quality. Grounding happens at the DVR the way I see it: the GND of the camera connects to the GND (i.e. the chassis) of the DVR...I can't think of a better way of doing it, though suggestions are always welcome in context, that is, excluding IP cams for the moment
      Wattevah...

      Comment


        #23
        Re: CCTV cameras: single PSU or individual PSUs ?

        Many cameras have fake pixel counts - under the fine print they are "5MP interpolated" but only 1MP raw.
        The white speckles can be a noisy CMOS sensor or sometimes the result of using too small capacitors in the camera module.
        The lines can be power supply ripple or hum pickup/grounding issues with analog video.
        You could swap out a camera to determine if it's the problem, or the site wiring etc.

        The Meanwell's work pretty good and have good SLA charging, temperature compensated like SCP-75 and switchover for UPS use.

        Comment


          #24
          Re: CCTV cameras: single PSU or individual PSUs ?

          Those "speckles" are probably not the best way of describing them: they're not there permanently, but occasionally just "dart" across the image like you'd sometimes see on VHS tapes, so I think it's safe to say they're not caused by the camera itself, since it happens on several of them, which would be a rare coincidence...
          Wattevah...

          Comment


            #25
            Re: CCTV cameras: single PSU or individual PSUs ?

            that can be caused by radiation striking the sensor.

            Comment


              #26
              Re: CCTV cameras: single PSU or individual PSUs ?

              Originally posted by stj View Post
              that can be caused by radiation striking the sensor.
              Where would such radiation come from ? :|
              Wattevah...

              Comment


                #27
                Re: CCTV cameras: single PSU or individual PSUs ?

                bad microwave ovens, radar, ukraine's 2 fucked power plants,
                the list is endless.

                Comment


                  #28
                  Re: CCTV cameras: single PSU or individual PSUs ?

                  Still on the topic of single vs individual PSUs, here's another scenario: regular household closet with multiple network switches, router, NAS, etc, each with their own power brick. How about hooking them all up to a single PSU ? The most obvious issue that I see is that if the PSU were to fail, ALL devices would go down at once. Other than that, is there something else I should be looking out for ?
                  Wattevah...

                  Comment


                    #29
                    Re: CCTV cameras: single PSU or individual PSUs ?

                    Which is why you get an overdesigned PSU that won't go down
                    Other than that, make sure each line is fused separately so a short won't take everything down either.

                    Comment


                      #30
                      Re: CCTV cameras: single PSU or individual PSUs ?

                      About that: I'm starting to question how "good" (or rather "decent") those generic PSUs from Ali truly are. I got a 10 amper running the DVR, a small peep-hole camera on the door and a small 7 inch monitor for live view at the moment. I've had it for about an year now and it's been running fine. The only problem is that I get some herring bone patterns on the monitor, which don't show up on the live feed if I access the DVR directly from the app or a PC, so there's something wrong with that analog output there. I haven't yet tried a separate PSU for the monitor itself to see if that changes anything. I believe I've grounded everything properly too (all GNDs together to the GND of the supply and even the case of the DVR), so it could just be the monitor is dodgy - it's a cheap nasty thing I picked up at a flea market....

                      I think I might actually have to dish out more and go with a MeanWell for my network stuff just to be on the safe side with stuff like ripple, output overshoot and overall life of the thing.....maybe...not sure...
                      Wattevah...

                      Comment


                        #31
                        Re: CCTV cameras: single PSU or individual PSUs ?

                        Ah, I haven't been back here in a while! Looks like you have some more interesting conversations going Danny.

                        I will say that I have had to deal with a fair amount of the "cheap chinese psu" power source for analogue cameras in my Career. (I am a network admin/it systems manager.) From what I have seen, the ones that are going to die tend do so either in the first year or after someone decides to push it too hard by adding in a bunch of extra cameras. (Ie: bumping it's utilization from 40% to 60%.) It seems to me that a lot of them could be decent/are decent but there are also a lot of them that don't have good cooling for their power transistors/mosfets. :/

                        Something I've always wanted to do is to take a few good quality server psu's and then use them as a redundant power backbone, like you would in a server. One of these days I'll grab an old server we are throwing out and do this. For now, I'm using a cheap ebay PSU that I analyzed/"fixed" of it's bad design flaws. (no thermal grease, unmatched mosfets, poor soldering, bad tank capacitors. lol)

                        Not that this is economically feasible for almost anyone, but one place I worked for used a 96 port Cisco POE switch (something like a Cisco Catalyst 4506) for all their security cameras. Now that is how it is done. lol They were already using these for the phones since they were a call center. Guess the lead admin wanted to stick with the same gear for security cameras.

                        One of these days I should make a video about what to check on those ebay PSU's and the things that generally are done poorly.


                        “Men always seem to think about their
                        past before they die, as though they were
                        frantically searching for proof that they
                        truly lived.”
                        – Jet (Cowboy Bebop) -

                        Comment


                          #32
                          Re: CCTV cameras: single PSU or individual PSUs ?

                          Originally posted by Retro-Hipster View Post
                          I will say that I have had to deal with a fair amount of the "cheap chinese psu" power source for analogue cameras in my Career. (I am a network admin/it systems manager.) From what I have seen, the ones that are going to die tend do so either in the first year or after someone decides to push it too hard by adding in a bunch of extra cameras. (Ie: bumping it's utilization from 40% to 60%.) It seems to me that a lot of them could be decent/are decent but there are also a lot of them that don't have good cooling for their power transistors/mosfets. :/
                          We're using 12V "bricks" from LCD monitors to power groups of (analog) cameras. If a brick fails, there are plenty more to choose from in the "discards" pile! (don't care what sort of barrel connector it uses as you'll cut that off when repurposing it)

                          Something I've always wanted to do is to take a few good quality server psu's and then use them as a redundant power backbone, like you would in a server. One of these days I'll grab an old server we are throwing out and do this. For now, I'm using a cheap ebay PSU that I analyzed/"fixed" of it's bad design flaws. (no thermal grease, unmatched mosfets, poor soldering, bad tank capacitors. lol)
                          I rescued several high-capacity (900-1100W), dual-redundant PSU assemblies (two power supplies in a "card cage", of sorts) from disk arrays -- gobs of 12VDC. I wire them in series and use them to power my electric wheelbarrow (instead of a pair of "car batteries").

                          Apparently, the RC crowd also uses these sorts of rescues to quick-charge their battery packs (?)

                          Comment


                            #33
                            Re: CCTV cameras: single PSU or individual PSUs ?

                            Yeah, I use rescue PSU's for all sorts of fun stuff. haha For instance, all the bench lighting on my bench is powered by the 12v from a psu. I also have a few of those little buck converters with the screens mounted around for a quick source of power. (Still have a decent Bench supply, but meh.) Most of the time though, the PSU's I deal with are just from old pc's. Because I'm "the boss" I worry that taking server type hardware home would set a bad example. (We often sell our old server stuff to reseller types.)


                            “Men always seem to think about their
                            past before they die, as though they were
                            frantically searching for proof that they
                            truly lived.”
                            – Jet (Cowboy Bebop) -

                            Comment


                              #34
                              Re: CCTV cameras: single PSU or individual PSUs ?

                              server psu's are in high demand,
                              car service guys and radio hams among others are buying a lot now.
                              also fucking a lot because they dont understand how they work and try to push them to 14v based on half-assed utube vids.

                              because as we all know, everybody with a utube channel is a god who knows exactly what they are doing!!! /sarc.

                              Comment


                                #35
                                Re: CCTV cameras: single PSU or individual PSUs ?

                                Speaking of server PSUs and going off topic, I ended up getting one at a hamfest that the seller ended up pitching as nobody wanted. Which sort of makes sense - there was no specific documentation about the PSU on even how to get it to turn on! Seems like it needed I2C or something to turn on, I did not find any !PSON pin.

                                I ended up putting in my own !PSON wire...

                                However it still doesn't work all that well, was able to power car headlight bulbs just fine but I know that I'm missing the feedback pins which I still have no clue which one it is... if there is one...

                                This is because the PSU appears to be single rail (all windings on one transformer), and if the +5 has more resistance than +12, how does one compensate for both without disturbing the other?

                                Hmm... lots of mysteries still to be solved.

                                Comment


                                  #36
                                  Re: CCTV cameras: single PSU or individual PSUs ?

                                  I was considering a regular ATX supply for powering my network sh!t, since I'm not sure it's a good idea to have both the network gear and the CCTV stuff on the same supply. Bonus: it's got a 5v output as well, should I need it, but then I thought that's not exactly "high quality", since all I have are a few boxes rescued from the junk pile which I just recapped....unless I spend a lot on a "proper" supply which defeats the whole purpose, since at that point I'm obviously better of getting an off the shelf power supply for far less money than the ATX supply at that. MeanWell seems to be the best maker of SMPSs, not counting ATXs. I think I settled on this LRS-150-12.....
                                  Last edited by Dannyx; 12-02-2019, 09:05 AM.
                                  Wattevah...

                                  Comment


                                    #37
                                    Re: CCTV cameras: single PSU or individual PSUs ?

                                    ATX PSUs? Reliable? Ever looked at this website?

                                    Comment


                                      #38
                                      Re: CCTV cameras: single PSU or individual PSUs ?

                                      Hmm... You know, you could make a super simple failover for a 12v bus by using a relay. So like, you could get 2 of those meanwell supplies and then have the psu's sitting in an active/passive setup. The primary would power the relay and the relay would be set in a normally closed position.. Then if that psu failed, it would cut power to the psu and switch over to the secondary psu.

                                      Kind of a janky hack, but it could be fun. haha I think to do it real proper you'd probably want to power the relay with something like a simple low voltage cuttoff (with latch). That way, if the primary started putting out something like 9v the cut over would be latched and not try to switch back to the primary. (To keep the relay from kicking back on the moment the primary load is lifted and the voltage floats back up to 12v.) This could probably be done with a mosfet, zener, some resistors, some diodes and a relay... that, or just a relay module and a micro controller. (yay for programmable logic.)


                                      “Men always seem to think about their
                                      past before they die, as though they were
                                      frantically searching for proof that they
                                      truly lived.”
                                      – Jet (Cowboy Bebop) -

                                      Comment


                                        #39
                                        Re: CCTV cameras: single PSU or individual PSUs ?

                                        How would you deal with initial power on? Draw a circuit?

                                        Normally people do PSU redundancy/failover with diode logic-OR structures, though it has significantly more loss than a relay (though the current flowing for a few CCTV cameras it's not as bad).

                                        That being said, I wonder if the complexity of using MOSFET switches is a better idea.

                                        Comment


                                          #40
                                          Re: CCTV cameras: single PSU or individual PSUs ?

                                          Ah, I will do so later for sure.

                                          In the simple circuit, I would be relying on something like this circuit (low-tech 12v battery undervoltage protection).


                                          The circuit would be powered by the "primary" psu. If the psu shut off or dropped below a voltage threshhold the relay would turn off and the normally closed position would engage. That would switch the LOAD to the secondary psu.

                                          The problem I see with this though is that the unloaded primary psu might turn back on and we would get flapping. That is why the circuit would need to latch.. But honestly, all of this is just my love of passive tech solutions showing through. lol I thought the idea of the "natural" failover that a relay would do as fun. I think that, like you said, Diode's and Mosfets could do this well.

                                          I think a better solution(than my simple relay solution) would honestly be diode OR logic powering a microcontroller. Then, the microcontroller would sense voltage on both psu's. If the primary's voltage drops below a threshold it would just turn off the relay which would switch things over to the secondary. From there the sky is really the limit on how you'd like to be informormed that the old psu failed. This could be a really fun ESP8266 type project. Have it connect to wireless and send an email alert to a recipient. The nice thing about this would be that you would both have the low ohm/high current capabilities of a relay and the versatility of an mpu.


                                          “Men always seem to think about their
                                          past before they die, as though they were
                                          frantically searching for proof that they
                                          truly lived.”
                                          – Jet (Cowboy Bebop) -

                                          Comment

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