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Owain

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Posts posted by Owain

  3. Posted

    So, you're suggesting feeding 50 Volts and regulating that to 12 Volts at the camera end? First, that "fix" goes beyond Class 2, which is limited to 24 Volts, so theoretically it requires an electrician to wire (almost as flaky an idea as running an extension cord to the camera). Second, 50 Volt power supplies are not that easy to find, nor are suitable DC-to-DC converters. And forget any other kind than switching.

     

    Yes. 48V / 50V is only the same voltage as telephone lines, and lower than some PoE implementations.

     

    Took me about two minutes to find a nice selection on ebay.com eg

    http://www.ebay.com/itm/110960049789

    http://www.ebay.com/itm/300452160874

     

    DC-DC converters about £10 each if you go to Ebay China. Twenty bucks US.

    http://www.ebay.com/itm/261147745875

     

    If the cameras are in clusters, one per camera might not be needed.

     

    You're right, it would be switched mode converters. I wasn't thinking of dropper resistors.

  4. Posted

    If you kick up the supply voltage to account for the voltage drop at 5 amps, you will likely fry the camera during daytime no load conditions and if you keep the supply voltage low enough during daytime no-movement to prevent over-voltage, the voltage at night under movement would be too low to power the camera.

     

    Not if the supply is (a) adequate, and (b) regulated. Note I specified a voltage converter at the camera end; the camera is not being supplied directly by the line voltage. Higher line voltage reduces the current, so reducing voltage drop, and regulating at the camera prevents any fluctuation in line voltage affecting the camera.

  5. Posted

    The baluns make no difference to the power, which is just a straight through connection.

     

    Voltage drop is dependent on the current, for the same power to reduce the current you will need to increase the voltage, so you could use a 50V telecom power supply and a DC-DC converter at the camera end to get back to 12V. Or use IP camera with power-over-IP which also uses a higher voltage than 12V. Or use heavier cable for the power. 2 x Cat5 would give you 7 pairs for power and 1 pair video.

  6. Posted

    2) how do you get the netview (the software from the unit) to work on the windows 7?

     

    Check the DM website downloads page, you may well find an updated version of Netview to install.

     

    I find that Netview takes about 10 minutes to start working - it may just be taking its time to get started on your computer, rather than "not working".

  14. Posted

    the problem is almost certainly infra red light from your camera reflecting back into the camera lens.

     

    Disable internal IR lighting and fit an external IR illuminator, or get a camera where the IR LEDs and the camera lens don't share the same front piece of glass.

  16. Posted

    The camera device itself will be an array of pixels. For an analogue camera, processing within the camera assembles these and generates an analogue composite video signal.

     

    For a cell phone, it's probable that the camera has no processing and passes the digital image directly to the phone's processing unit. There is thus no analogue signal to extract.

     

    Building your own circuit to do so would be synonymous with designing and building a PC graphics card, from scratch, without any documentation, and using discrete logic because the specialised chips are for manufacturers only.

  18. Posted

    hey folks maybe someone can help i have the ds2a with cd writer and keyboard plus ptz's what i want to do is to turn on the lights outside if i hear someone hanging around but do it thruough the ds2 keyboard theres a button to toggle wipers and washer plus lights but id like to know how it is able to get working. cheers

     

    your camera has to have a lights switch output, or you can use a separate relay controlled by the RS422/485.

     

    Something like

    http://www.bbvcctv.com/products/receivers/rx25x_multiple_protocol_auxiliary_relay_receiver/

     

    A more DIY approach

    http://www.sigma-shop.com/category/17/rs485-relays.html

  20. Posted

    @Owain, I understand how IP addresses work. I have already gone through all of the DVR settings. it has a static IP address set. the DSL modem/router settings show that it IS connecting using that IP address. that IP address has been assigned in the DHCP settings as belonging to the DVR. I was operating under the assumption that this was obvious.

     

    Well, it is now you've said it, but you didn't say it before, so we didn't know exactly what settings you were using. And fault-finding is usually a process of systematic elminiation rather than inspired guesswork. Finally, other people may have a similar problem and read this forum months later, so it's useful to spell things out as they may not have taken all the steps you have.

     

    Does your DVR have, and can you connect to, its internal webserver by pointing a browser at the IP address on port 80? If you can't then the router or hub/switch is doing something with the IP.

  21. Posted

    you need to start with how you are going to magnify the image. Either analogue video with optical zoom, which will need a zoom lens and a controller, or a megapixel camera and do the zoom digitally.

     

    Zoom lenses, controller keyboards etc can get expensive and I'd be inclined to use digital. I'd suggest starting with a megapixel webcam as these are quite cheap, and seeing how you get on, or asking the people at networkwebcams as they're expeirenced with megapixel IP cameras.

     

    If the aim is magnification of print i.e. a 2-dimensional surface, then video magnifiers are already available, output to either TV, VGA or USB. I don't know how well they'd cope with 3D objects, and as with most things for 'the disabled' the prices are hiked.

     

    http://www.eschenbach.com/products-video-magnifiers-desktop.htm

  22. Posted

    Very likely the IP address of the DVR has changed.

     

    The DVR may have a setting for fixed IP address in its network setup. You will have to tell the client software on the PC to connect to the DVR using that new address.

     

    You could also check the router settings for client IP addresses (look for DHCP server settings) and if the DVR can only use a 'static IP' address you must exclude the address used by the DVR from the address block offered by the router for DHCP, so that nothing else can use the same IP address that the DVR has.

  23. Posted

    If a DVR is 4-camera then it should record all 4 cameras.

     

    If the DVR has an alarm relay output which is motion activated, OR if you use a PIR detector next to the camera, you can use that to apply a voltage to one of the TV SCART connectors, and the TV may then switch to that input. Not all TVs will autoswitch to SCART inputs.

     

    Pin 8:

    5–8 V → on/16:9

    9.5–12 V → on/4:3

    Pin 14: Data Ground

  24. Posted

    Most modern analogue DVRs have network connections for remote viewing already.

     

    1. There are IP-over-coax solutions, but usually you would install Cat 5/6 ethernet which can often carry the camera power as well.

     

    2. Max length for ethernet will be about 300 ft; IP cameras use various flavours of Power-over-Ethernet and the distance depends on the PoE type and the camera.

     

    3. Most cameras will use DHCP and get an IP address automatically, so just set up a DHCP server with the appropriate network address ranges.

     

    4. IP cameras use IP over ethernet - it's all just packets. You will need to calculate network bandwidth, but many IP cameras can have on-board storage so you can view over the network in low res and store high res on the camera. Cameras will do periodic uploads to FTP server or NAS (which can be cloud based).

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