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ian_flux

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Posts posted by ian_flux

  2. Posted

    It is perfectly normal on some equipment to have a common ground, but that doesn't explain the presence of a positive that continues to power the camera when the positive is removed. If you remove the neutral of a supply, the voltage may continue to flow (due to design flaws) and neutral terminals will rise to supply voltage. But this is not the same.

     

    Are the power supplies definitely DC out? - I did ask.

     

    The possibility of the positive of a low voltage DC power supply making its way to cameras through an earth or metal is fairly unlikely, unless the cables were damaged and are making a fair contact in some way at both ends.

     

    I'm unsure about inductance with DC circuits but its very possible on AC cables running close to induce voltage in others. Your runs are long on CCA... So I would look at two things:

     

    1) Creating separation between cables (if possible)

    2) Run your power on pairs only (definitely try this)

     

    So if you currently run a pair for Positive and a pair for Negative, turn it into 2 x Pair of Pos/Neg. And do not have more Neg than Pos or vice versa.

  3. Posted

    Hi all,

     

    I'm currently in Surrey, and moving further south to Kent soon enough.

     

    I left the world of door entry and intruder alarms (where i dealt with my first CCTV systems), to work in the exciting world of electricity distribution and metering...

     

    I'm now attempting to set up my own company: Alarms, CCTV and external lighting. It would be nice to connect with other/similar trades in surrounding areas, for cross promotion and to create the complete solution; locksmiths, fencing, gates and others in the same trade.

     

    Ian

  5. Posted

    As long as the two are compatible. If the camera has a standard audio line in, and the mixer provides the same out, then it should work.

     

    The specs for the camera should tell you the standards. Just confirm it's not a microphone input. If the mixer provides the kind of line out that plugs straight in to an amplifier then it should be ok. Just bear in mind that if the camera is two wires in, this will be mono and most 'typical' mixers unless just for microphone inputs, will be stereo.

  6. Posted

    if i take off positive and leave negative on almost all of them the cameras still stay on..

    This is getting confusing. I'm telling you to make sure the only negative that supplies the cameras is that from the power supply that feeds them. I'm trying to make sure you are not accidentally interconnecting negatives, earths and grounds that shouldn't be.

     

    That statement sounds the wrong way round to me and if you'd have said you removed the negative and the cameras still worked then I'd say that probably proves a ground loop via the DVR earth. In other words the shield/screen out of the DVR is interconnected with your camera power supplies somewhere. I have no idea how they would be getting a positive voltage. Are the power supplies DC out or AC?

     

    I think you need to have an understanding of what is happening in your system. Do you have any previous experience with electronics or basic electrical principles?

  7. Posted

    Its nothing I recognise.

     

    Unless the operating system is located on the hard drive, its unlikely that the configuration will be stored there. Most DVRs are bios/eprom based meaning a fast start, and no corruption even if a hard drive dies or power supply is lost.

     

    In my experience, the password info seems to be stored in an portion of NVM (non volatile memory), so just like many intruder alarms, power supply fails and dead batteries have no effect. In many devices you can reset NVM by shorting two pins but please don't just try random pins you see. It's nothing I've ever needed to do on a DVR but security panels yes, and its fairly normal to short NVM pins with the power on, or while powering up.

     

    Before you even try that, have you tried simple code combinations yet? Some systems have a default very weak password when it is enabled, which many users don't change. Other systems have a blank field, into which many users set a very easy password.

     

    Defaults are usually between 4 and 6 digits, anything from 0000, 1111, 9999, 12345, 123456, etc.

  8. Posted

    i did try one by one, but there are so many cameras that cause issues with other cameras.. Now i have like 9 cameras separate box , 6 cameras seperate box , 3 cameras separate box , 3 cameras seperate adapter and 2 and 2 seprate adapters and 1 on a adapter on its own... if i mix any of these with any of the others they'll mess up each other.. so i gave up and just bought separate power supplies 2A for only $3 and just ill hook half of them up to individual adapters.. and be done lol .. driving me nuts..

    So you think its a power supply problem? Is that because when others were powered down, your problem cameras looked better? Did you even check volt drop? Have you tested a 'bad' camera separately as Boogieman suggested? Did you swap out baluns on a 'bad' camera?

     

    I hope your idea helps you but it sounds crazy to me to just swap out PSUs with no evidence of the problem in the first place.

     

    I'll ask one other question just out of curiosity: How do all your cables run out of the DVR room and to where they start to split off? Are they on a cable tray, or tacked next to each other on the wall, or are they bundled up and tied together?

     

    If your new PSUs don't fix it, you will have to look at interference - as has been suggested, cheap CCA, with cheap baluns could cause problems amongst a bundle of cables running very close together.

     

    And if you really think it's down to a ground loop problem, make sure only the cameras have a negative from the PSU, don't attempt to interconnect any other earths, grounds unless it is specifically required. Most ground loop problems are solved by isolation. I'm only saying this because you said some of your boxes were grounded, and I'm not sure what you meant by that.

  10. Posted

    The images are all over the place due to ground balance, the simple way to fix this is to ground the DVR to the power supply feeding the camera's.

     

    There is an Earth point on the rear of the nvr just connect that to -over

    And all will be clear.

     

    Next time use IP equipment, or rj45 passive splitters to keep things tidy, no one likes a messy install.

    If that cures the problem, then respect to you and I will have learnt something. But my understanding is that it is often the interconnection of grounds of two pieces of equipment via an unintended route that causes a ground loop in the first place.

     

    In theory, connecting both grounds together sounds like a good idea, but generally speaking, if you're talking about a real earth terminal on back of DVR, the DC ground is not the same as the AC ground, if you mean a DC ground terminal, then two DC supply grounds shouldn't really be connected.

     

    The output from DC supplies are normally intended to be floating, if the DC output should be grounded (to AC ground (Earth)) then this will be done by design, in the power supply.

  11. Posted

    So analog has never been able to identify anyone ?

    Those are not my words. I just think its time to look further forward now.

     

    All of the equipment I've ever worked with so far has been analogue. A long time back, I even had dealings with timelapse VCR systems, they seemed great at the time but then we had DVRs and then we got to D1...

     

    Think about it as an advantage to possibly having to fit less cameras, and definitely having less dilemma about field of view vs position.

     

    With better quality, one good frame with magnification increases possibility to identify significantly.

     

    720p = 3 x D1 pixels

    1080p = 6 x D1 pixels

  12. Posted

    I think it matters.

     

    Sooner or later the industry will retire analogue and it will become a legacy format. Sooner or later many customers will expect a higher resolution format.

     

    A shop I recently visited had eight cameras in a very small trading area. The shopkeepers primary concern being, he wanted to be able to identify criminals and what they had done clearly, post event. I would say that with a higher resolution, identification is going to be much easier.

     

    Its impossible to control everyone and use, for example, NPR where people are free to roam. There's a limited number of channels and people don't want maximum amount of cameras. Only today I had to use an analogue PTZ to identify a number plate. A higher res fixed camera could have provided the info if I hadn't of been there to operate the camera.

     

    Every so often, the police are looking for a fuzzy faced man - have you seen him?

  13. Posted

    Ok. It was an example, but I appreciate that. I need UK suppliers anyway!

     

    I also see that NVRs have held their prices because of the arrival of POE units. I can buy a 32CH non POE NVR for £16 more than a nearly identical 8CH POE unit. If I can find a reputable supplier with reasonable prices I'll actually consider IP over TVI.

  14. Posted

    I'm currently looking at TVI and Hybrid systems. I can't quite see what the 'Turbo' relates to exactly, some sites say they support real time @ 1080p, some say they don't, so I'm a little confused. Most TVI/hybrid claim to run between 12 and 15 fps @ 1080p. I'm not so fussed about framerate if the quality is that much better tbh.

     

    I think I did find a Hybrid (tribrid ) SD, TVI and IP that claims to be real time. I'll post a link if I find it amongst the tons of bookmarks.

  15. Posted

    Thanks for your opinions.

     

    The linked site misleads people. Wicked, all I have to say. There is no specific reason, technically, for HD-TVI to perform better than HD-CVI or HD-AHD. Let them compete each other so that end users can enjoy better quality and better price. HD-SDI, carrying video in form of raw digital, no compression, is still expensive when compared to those HD-Analogs, listed above. And CCTV is becomng Cost driven market, not tech driven any longer. So HD_SDI seems to be losing its ground.

    I'm wondering if that site only trades with particular manufacturers and thus are excluding the other technologies solely for that reason.

     

    TVI and CVI are readily available, cheap and have lots of camera choices...new installs should be IP (for most applications, that the very least run ethernet and use baluns so the system can be easily upgraded in the future)..these are transitional technologies.

    I'm including analogue HD because despite a flood of no name IP cameras at very reasonable prices recently, the price difference is still very clear. For example, the linked site is pushing an 8CH TVI with cams for just under $1k, but the IP equivalent is just over $2k.

     

    CCTV is becomng Cost driven market, not tech driven any longer.

    So am I being unrealistic to rule out the cheaper brands? I posted a question where I said I thought all the DVRs now looked like generic black boxes, with poorly designed front panels.

  18. Posted

    I'm finding lots of similar sites pushing really cheap equipment that in reality just has a different brand applied to the case: http://www.icctvuk.co.uk/cctv-camera-dome-aveesa-800tvl-varifocal-black/

     

    Not an identical camera (and it is varifocal), but compare a few products on both sites and you'll get the idea. Also, with these sites, their DVR range is limited to about three brands.

     

    Many customers will be happy with the 'great value', but after installing a few better quality products, you'll see the difference and maybe start to recommend them instead.

     

    Anyway, I would be cautious about using any standard analogue equipment, when the industry really is moving to HD. Good quality images could make a difference to the amount of cameras you need to install.

  24. Posted

    Yes, if I felt I needed more than two cores for power, then I would share the other pair across the -/+

     

    I would just take it a step at a time.

     

    Voltage at problem cameras OK?

    No - Volt drop due to distance/poor cable/bad terminations?

    No - Supply not large enough for amount of cameras?

     

    Baluns, at both ends of bad cameras swapped for 'good' ones?

    Termination checked? (it is common practice to score cores of cable when stripping them)

     

    Could be interference?

    -> disconnect as much as possible while testing

    -> ground other cores, disconnect other baluns while testing

     

    In other words, make it as basic as you can and go through it methodically, which is why I suggest just seeing what a single camera, being powered, and providing a signal through a single pair of baluns looks like. Also, are your problem cameras the furthest away, and have you looked for a source of interference near those particular cameras?

     

    The whole DC ground, real (earth) ground issues can be tricky, but thankfully I've not had to overcome them yet.

  25. Posted

    Users who buy from reputable sellers dont have these issues. The seller does not get paid unless you approve the transaction. You credit card provides additional protection. As far as the credit cards being stolen the sellers NEVER get the card info. Ali is just as secure as ebay/amazon.

    I'm not going to open all my old bookmarks, but I assure you that there's too many complaints about the website for me to take it seriously or want to part with big money that way. I'd rather support a trusted distribution chain and pay a little more money. Besides, waiting up to 28 days for delivery and then having to cover return costs if there's a problem, isn't an ideal trading platform for me. Here are a couple of the first links I found.

     

    https://uk.trustpilot.com/review/www.alibaba.com

    http://andrewminalto.com/alibaba-scam-exposed/

     

    The second link seems to be an article defending Alibaba, but just look at the comments at the bottom. This seems very much like ebay to me, where, with a careful eye, you can weed out most of the bad deals, duplicate accounts and fake goods - but unfortunately many people can't do this and make complaints.

     

    I would suggest a reputable seller would be a trusted CCTV distributor or wholesaler.

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