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tube tech

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  1. tube tech

    50 Ohm BNC vs 75 Ohm BNC

    most 50 ohm is RG-58. Most 75 ohm is RG-59 or RG-6. physical specs can be googled. RG-58 & RG-6 should have one center conductor, RG-58 has many strands The physical specs are considered to be more of a guideline than a contract in many asian countries. ebay BNC crimp on connectors don't crimp right on CCTV siamesed cable, which is apparently RG-58 1/2 you could make a TDR with a pulse generator and a scope. If you have to ask, don't bother, it would take way too long to explain If you have a big spool of cable, connect the color bar generator to the monitor and the spool, with a T on the connection and a 75 ohm load on the far end of the cable. It it's 75 ohm cable, no reflection. It it's 50 ohm, you get a ghost image down and right of the real image 50 feet of cable is enough to see this effect
  2. brand names are essentially meaningless. they are all made in People Factory 43, somewhere in China. check out cameras on eBay & Supercircuits: same picture, price ranges from $7.39 to $197.39 for the exact same camera.
  3. this is one of very few instances where 5.8 ghz wireless is practical. the range limitation is not a problem, the bandwidth is mostly unused
  4. tube tech

    DVR and NVR?

    my junior high math teacher would say that NVR is a subset of DVR, draw a circle in a circle, make them different colors.
  5. you can see the NVR over IP. I feed the composite video to Channelplus 5545 modulators to make all NVRs visible on all TVs. I bought the CCTV system from an apartment building off of eBay, learned a whole new skill set.
  6. I have two. Hornet hell. imagine a hornet landing on a 1.8 mm wide angle lens, seen on a 52" TV. a hundred times a day. looks like a danged eagle. you have to seal the birdhouse, put a plate or screen around the opening. not difficult, but it's better to do it before the softball sized nest of stingy things shows up. black towel over the drapes kills reflections
  7. tube tech

    Want to catch the clown trying to break in

    generic advice, from a retired video tech running 24 cameras, with more on the way: a ratio of two high cameras to one eye level. two eye level cameras where a person has to pause to get in. one to the side, one face on, just like a mug shot, for exactly that reason. the quality of the image is limited by the quality of the lens. most CCTV cameras have cast acrylic lenses. I can identify people I know, identifying a stranger would require serious glass lenses and a camera that can support them. the eye level mugshot cameras need to be a cut above the generic "there's somebody out there" cameras.
  8. OP, read this. It's boring and no fun, but necessary: https://www.mikeholt.com/instructor2/img/product/pdf/11LE-968-sample.pdf no point proceeding until you are in tune with the NEC.
  9. tube tech

    CCTV for artist

    This is not an answer to your question, but it's something some artist somewhere can use: this very inexpensive camera: https://www.ebay.com/itm/262634696678?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649 Is an infrared camera. there is a glass filter on the back of the lens. if you remove this lens by shattering it out of existence or if you use a different lens, you get a CCTV camera that produces results between those of B&W and color IR film. I have a regular CCD cam and one of these side by side. Both have blue skies, one has green trees, one looks like it just snowed if that ebay address goes sour, search for UPC: 190268124935
  10. farther back is better, keeps it out of the rain and cooler in summer.
  11. If your house catches fire, and the insurance company finds something not up to code, they don't have to pay up. Even if the code violation has nothing to do with the fire. If you did not know that, you should not be giving advice. If you did know that, you should be able to post the link to that excellent PDF that clarifies the appropriate code.
  12. This happens every day in my system. The cameras that point due east, then the southeast cams, then the south cams, shifting to the southwest, ending up in the west... Like they are following the path of something. Possibly an intense light source.
  13. tube tech

    I want to buy a security camera right for me. Help!

    look up usb charger camera on ebay
  14. that is your problem. CMOS effectively stands for Can't Make Out Spit, and I erred in the spelling of that last word Sony Super HAD CCD or nothing.
  15. A router is a server with 2 network connectors, and software that determines when to connect them to each other. What is called a wireless router is a server with one network connection to a larger network - the WAN connector - and a switch which usually connects 4 ports to each other. a wireless router is a router, switch, and access point in one box. you need a switch to connect the cameras to each other and the computer you use to view the video. A router works fine as a switch.
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