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Video signal amplifier.

Discussion in 'Audio' started by HANKMARS, Jul 28, 2019.

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  1. davenn

    davenn Moderator

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    Sep 5, 2009

    Of course it's needed …. it doesn't need to be an RF signal.
    A balun is used ANYWHERE where you need to match impedances
     
    HANKMARS likes this.
  2. davenn

    davenn Moderator

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    Sep 5, 2009

    Yes, agreed, for anything over ~ 100 ft 30 metres Ethernet should be used

    That was going to be my next suggestion/recommendation
     
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  3. Audioguru

    Audioguru

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    Sep 24, 2016
    You showed a very slow opamp as non-inverting with a single negative feedback resistor. Its input might or might not be biased properly by the signal source. Your opamp circuit showed no power supply connections. It did not have a series input resistor used in an inverting opamp amplifier.
    Since it has only a single feedback resistor (which can be a simple piece of wire) then its voltage gain is 1. If its (-) input had a second resistor connected to ground then it would have a gain of the ratio of the resistor values.

    NTSC sync pulses repeat at about 15.7kHz but they are very narrow (short duration) which needs a good high frequency response circuit to produce them. Your very slow opamp cannot doo dat.
     

    Attached Files:

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  4. aurelZ

    aurelZ

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    Jun 10, 2019
    Yes i agree with Audioguru i doubt that this IC can provide enough gain for 100ft cable.
    Another thing:
    As far as i know most cameras have composite chinch 75ohm output
    so if you use Z=75 ohm cable then you don't need any baloon transformer.
    Ethernet cable as such is for LAN network cable and is not good for
    transfer analog video signal on such a distance, only in case if is shilded
    then might be used.
    for example i see security camera which is connected with coaxial RG65 cable and work fine
    but distance is cca 10m.
     
  5. aurelZ

    aurelZ

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    Jun 10, 2019
    VideoAMP.gif Something like this:
     
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  6. davenn

    davenn Moderator

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    Sep 5, 2009

    You really need to do some reading up on how ethernet is used for long video runs
    It's apparent that you don't understand the process
     
    hevans1944 likes this.
  7. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Indeed. And if anyone tries to explain it in any detail, they are accused of putting up a "Wall of Text." Perhaps this perception arises from the fact that @aurelZ has stated "Just to let you know ,i finished my high electronic school somewhere at the end of 1988." Some people believe that once a certain level of education (usually mandatory) is finished, they are done learning for life, except for what they get from "hands on" experience. I am a true-believer in the value of such experience, but education should be a life-long process ultimately leading to death. It's not the destination that is important: it is the journey to get there.

    Below is a picture of a Toshiba IK-WB16A zoom-pan-tilt CCTV "web camera" that I purchased a few years ago to monitor suspicious activity inside and outside my home via a local area network (LAN) connection using CAT5 cable and RJ45 connectors to a hardwired port on my wireless router. I have a Cisco Ethernet switch attached to one of these hardware ports, so I can expand the "view" if necessary. This camera is also available with a WiFi wireless signal adapter built in, for those needing this convenience or not wanting to use cable wiring. BTW, the Toshiba outdoor weatherproof housing for this camera costs about the same as the camera itself, but you get what you pay for.

    upload_2019-8-6_11-14-21.jpeg

    Unlike the typical "lipstick" camera that produces low-resolution 525-line NTSC video, this is a very high resolution camera that produces video in resolutions up to 1600 x 1200 at 15 frames per second. Higher frame rates, up to 30 fps, can be obtained if resolution is reduced. Detailed information (a Wall of Text) can be found in the User's Manual, a PDF file located here. Camera specs are at the very end of the document.

    The video is digitized and sent as Ethernet packets, with a minimum Ethernet specification of a 10BaseT network, over my home LAN, which consists of wired as well as wireless elements. If desired, I can open ports and "expose" the camera to the Internet, allowing access to it from anywhere there is an Internet connection available, including my iPhone 6 cell phone or my wife's iPhone 7 cell phone. Toshiba provides free software, for Windows PCs only, that enables motion detection. So, a streaming video recording to my local area network drive is also available for review.

    Note that I am not suggesting the OP ditch the cheap "lipstick camera," but it is possible to convert its NTSC video into Ethernet packets, with appropriate hardware and software, and send those packets over considerable distances with just CAT5 cable alone, or even send the packets world-wide with a broadband Internet connection. Lots of things are possible for anyone with deep enough pockets full of cash, willing to read past a "Wall of Text" and learn something new.
     
    Last edited: Aug 6, 2019
    davenn likes this.
  8. aurelZ

    aurelZ

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    Jun 10, 2019
    Wait a moment ..
    do you really think that i don't know that such a type of camera exists?
    come on.. i know of course and i agree that you can with such a camera send digital signal trough
    LAN crossover cable to larger distances.
    so nothing wrong with that .
    BUT ,,Original Poster ask for ordinary small camera without such a thing and he ask
    for video amplifier..right?
    You don't need to lern me things i already know.
    Long time ago ...maybe 10 or 12 i don't know exactly
    me and my two friends build first WiFi network in our small town to enable wifi internet
    and then i lern a lot about LAN cabels,wiFi things ..etc..etc...
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009

    ohhh dear :( :( not what you said earlier



    yes he did, but for 500 ft it's unrealistic and difficult because of the signal degradation

    AND THAT is why it has been suggested to him to go the ethernet way
     
  10. aurelZ

    aurelZ

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    Jun 10, 2019
    Ok length is cca 150 m
    and i think that you have right with a suggestion
    BUT then i found on internet this statement:
    The maximum length depends on a couple of things such as the transmission speed and the Category of twisted-pair LAN cable being used. Typically, for 10/100/1000 mbps links, 100 meters (approx. 300 ft.) is the maximum length for cables with Cat5e or better.Mar 24, 2018
    In real we(me) never use more than 20 m longer lan cable.
    But that is just me..
     
  11. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    I think maybe I or someone else here has alienated @HANKMARS, because he hasn't responded lately. He came here looking for a "simple" solution to his "problem" of how to send color video from a cheap "lipstick" camera down 500 feet of some unspecified cable using a 747 op-amp. What he got was a lot of folks telling him why it couldn't be done, without anyone (me included) offering any specific advice on how he could do it.

    I will personally apologize for that, but I am hesitant to offer any suggestions on how to send color video (by any means) over 500 feet of unspecified cable. I could guess, since it was stated that this length of cable was wound on a spool, that flat "telephone wire" type cable was purchased by the end user. But without more information it is impossible to make any specific recommendations that are meaningful... without guesswork in other words.
     
    HANKMARS likes this.
  12. WHONOES

    WHONOES

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    May 20, 2017
    I would suggest that he use RG178 which is a 1.78mm diameter 50Ω cable properly terminated at each end, as mentioned earlier, and an AD811 video amp with a gain of 2 to compensate for reduction of signal be the termination.
     
    HANKMARS likes this.
  13. HANKMARS

    HANKMARS

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    Jul 28, 2019
    WHONOES indeed appears to be well acquainted with this subject. When I initially peeked at this project, the mention of baluns came about. I had never used a manufactured balun but deduced that the root of the word was bal, most likely in reference to an act of balancing a supply to a load. Balancing, I presume is another term for impedance matching. I will have to look up differential transmitters and receivers. My use of differential amps generally produced a short spike due to a change in potential of a signal. If I needed to develop common mode rejection, I had planned on a simple op-amp circuit. I am losing color information. Some signal amp designs that I have looked at, put what they refer to as a pre-amp, in-line,just prior to the device (in this case a digital monitor) that will be processing the data. It is my guess that the information in the app, will be too degraded to recover. Therefore, I thought I would amplify the signal prior to transmission over spooled cable. The signal from the camera is clean. It looks as though the horizontal sync pulse is at ground potential. For an entire pulse of information, the time period is in the neighborhood of 60μs. Front porch, hor sync pulse, back porch with 3 color information at 3 distinct voltage levels, with blanking, etc. Thank you for your input. MDH 08/09/19
     
  14. HANKMARS

    HANKMARS

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    Jul 28, 2019
    I have a couple AD811s on their way. Haven't gotten back to experimenting but the 811s look like an ideal amp for this app.
     
  15. HANKMARS

    HANKMARS

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    Jul 28, 2019
    No apologies necessary at all. I have other irons in the fire, plus everyday life events, plus occasional wifi problems. Let me give you some cable numbers. Cable is a 4 conductor shielded type. 18awg solid. Stamped info as follows: E111272 (05-21513) 18AWG SHIELDED CL 3R/FPLR (UL) OR CMR C(UL) US (06/11) RoHS 081342FT. The spool itself is no high tech item. Best guess is that its intended use is to spool up 110VAC power cord. Probably a brass slip ring over a stationary brass ring. Any genuine info or ideas are quite welcome. But I am quite capable of inventing the wild goose chases on my own. Thank you for your input. MDH 08/09/10
     
  16. hevans1944

    hevans1944 Hop - AC8NS

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    Amplification along with some other "analog magic" to recover bandwidth lost in the cable could be useful, but 500 feet is a loong distance for raw NTSC analog video. Please take the time to research how an NTSC color signal is assembled. The 60μs
     
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  17. WHONOES

    WHONOES

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    May 20, 2017
    HANKMARS likes this.
  18. HANKMARS

    HANKMARS

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    Jul 28, 2019
    The camera requires a 12VDC supply. A single cable is mandatory. I suppose I could send the 12VDC over the coax, let the signal piggyback on the power line and strip it off, but that may be troublesome, or not.
     
  19. HANKMARS

    HANKMARS

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    Jul 28, 2019
    That is the block diagram, yes.
     
  20. HANKMARS

    HANKMARS

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    Jul 28, 2019
    Agreed. The circuits showed in your attachment will be my next build. I obtained them from the AD811 data sheets, application notes.
     
    Last edited: Aug 11, 2019
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