VGA CAT5 Extension Cable

rj45 cable

[Ladada2001] sent along a project link for building a VGA extension cable using CAT5. This particular project was for a projector with BNC connectors. This has been a particularly popular (and easy) topic in the past. We’ve seen an example from ElephantStaircase. The 5-in-1 cable featured in Make also had provisions for VGA. If you build one of these cables you should be able to get decent performance at 50 feet.

30 thoughts on “VGA CAT5 Extension Cable

  1. I don’t believe so, wrathofpyro. The standards are not compatible. The VGA connector provides Red, Blue, and Green component video lines, but the RCA composite video consists of a Y signal for Luminance/Brightness and a UV signal which itself is composed of two separate colour signals mixed with a colour carrier frequency. You could probably do it, but at that point it’s not a simple hack anymore and you’re better off buying a stock converter of some kind. (Assuming one even exists.)

  2. You COULD get a PS2 component cable and a component-RGB converter (read: not cheap), but I don’t think it’d be worth your while. There’s also the option of getting a sync converter and a modchip (this would be the hacker way), but that’s also expensive (not to mention dangerous for your PS2).

    One thing that bothers me about these Cat5 VGA mods is something an electronics pro told me: VGA cables are measured (with a square wave sent down each wire) so that the signals all arrive at the same time. However, Cat5 wires are NOT measured that way, and therefore you get more and more crap in your video as lengths get longer (and because Cat5 usually arrives coiled, some wires are already longer than others). Pros get around these things by some sort of adjustment (he didn’t go into detail, but from what I can imagine, there are special controls that can add or subtract small amounts of length to or from your connections).

    Is this true, or is this negligible for these distances?

  3. Nuts. I tried to convince my dad at his office to do this but he wouldnt do it. I knew i had seen plans for this somewhere

    Then I tried to get him to do the USB through the Ethernet cable sitting at the desk. Nope had to pull a cable for that also.

    The computer sits 15 feet away in a closet. VGA over Cat5? nope had to spider a cable that far.

    Hope he is happy.

  4. wrathofpyro, if I understand what you are asking, nearly any off the shelf VGA box should do what you want. They take Composite/S-Video/Component input, and display it on a VGA monitor.

    The only problem with that is, the PS2 has very few Progressive Scan games, so the VGA box is going to have to handle the conversion from the 480i output of the PS2 to 480p, which might not look all that great depending on the quality of the unit.

    Of course, you would need Component cables for the PS2 as well to get progressive scan.

  5. 6:
    sounds probable. i was thinking that you’d also get a lot of noise/interference with cat5 cable b/c the lack of proper shielding, which a normal vga cable would have, since vga is an analog signal.

  6. If you really want to go technical (read: expensive), buy some cat6 cable, stranded, no less. It cuts down on the noise considerably, but costs a sh*tload more than cat5. Thicker, too.

    Also, it helps a bunch if you keep the VGA cable away from any power cable. I noticed wierd “cross-hatching” in my monitor when I used to use VGA, and moving the cable away from the monitor’s power helps a ton.

  7. there would be no shielding of the vga signal unless it used balanced lines like cat5 was ment to be used. unless i have something horribly wrong i dont think there would be any shielding at all

  8. I built one of these a while back to run in my home theater. I’m pretty picky about video quality, and I can’t see any video interference from this setup over what I had previously used. If you have doubts – check out where the real videophile nuts hang out and read the debates there.

    If you do a google search for

  9. That was awesome, it’s cool how cat5 can be so virsitile. I was wondering about that vga to component cable. Right now i have a pc, which i use as a media-center, hooked to my plasma tv through a scan converter. The problem is that the scan convertr down-converts any signal it gets to 720×480, for compadibility. I know my tv’s capable of more than that. Could i use the vga to component cable to bypass the scan converter and use higher resolutions? I have a radeon 7000 series card in that computer if it matters. Thanks.

  10. cat5 is almost as useful as duct tape. cable extensions, speaker wire, I even used it as a belt once when I ran out of the house in a hurry to get to work and forgot mine.

  11. wrathofpyro,

    what you need is a transcoder. if you only need RCA to VGA you can find them cheap. If you want component to VGA it will run $100-$300+

    I have a Nextvision 6 i use for my xbox and it works great! sometimes you can snag one from ebay for cheap (payed ~$130 for mine)

  12. VGA is NOT the same thing as component :D

    VGA is R/G/B. Component is NOT, however you can transmit VGA over RGB cables, which are the same as component just the signals are not the same, This is why we don’t see VGA->Component adapters. A short explanation….

    “Component video consists of three signals. The first is the luminance signal, which indicates brightness or black & white information that is contained in the original RGB signal. It is referred to as the “Y” component. The second and third signals are called “color difference” signals which indicate how much blue and red there is relative to luminance. The blue component is “B-Y” and the red component is “R-Y”. The color difference signals are mathematical derivatives of the RGB signal.”

    Component operates on difference, not additive color.

  13. What about a extender with stereo audio signal AND s-video? audio uses two pair, the s-video uses the other two… so far its fine, but how about noise one on the other? Is a booster recommended? Anyone knows how to make a booster for AV???

  14. wrathofpyro: no. different video standards.

    luiz_borges: I got a lot of ghosting etc over even a fairly short run doing that, but I suspect the cable runs over top of some lighting or heating wires in the ceiling. ymmv. worth a try though I would think :)

  15. This is cool. For those that don’t understand? There is a trick involved in this.
    Every “pair” of wires in the cat 5 cable “must” be transmitting and receiveing the two sides of the SAME SIGNAL. IE, if there is a high frequency video signal on 1 wire, the corresponding ground return for that same signal MUST go through the other cable (the same color). That is what gives you the shielding effect. Any EMI induced in one wire has the counter EMI induced in the other half of the twisted pair. Since the counter EMI is induced in the exact same voltage but “backwards” to the original the EMI is canceled out at the end (where the monitor is at). If you make the mistake of just thinking of the cat 5 cable as 8 wires, you will never make a cable like this work. If you are carefull to ensure that each signal goes thru a “twisted pair”.. this will work.. as well as a shielded cable.
    As I remember it, a VGA cable has 3 color signals going through it. One for Red, Green and Blue. The remaining 2 wires are used to piggyback the rest of the pins. Since they don’t carry high freguency AC, they don’t matter as much. Only the 3 AC signals for the 3 colors really matters for video quality.
    The only pitfall of Twisted pair (cat 5) over Shielded (VGA Cable) is at higher frequencys. Once the wavelength of the EMI interference gets close to the twists per inch of the Cat 5 cable? The EMI can induce into one cable more then the other. This means the shielding effect works best at low frequencys (like power cables) Just keep it away from super high frequency stuff….. and make sure that any high frequency signals get transmitted and returned on a single pair of twisted wires.
    If you understand this simple rule, you can send any high frequency signal over a Cat 5 cable as long as there are 4 or less high frequency signals. (Component only uses 3 so it will work). oh… It is recommended you keep the bends of the Cat 5 cable to a minumum. If you make a sharp bend in the cable, you can cause signal degradation at the bend….

  16. Your cable is out of spec. A good VGA cable requires 75 ohm internal cables. If you were to run that cable for a longer distance you would start getting convergance errors and rf problems. You might want to try building a high quality cable with five 75 ohm tv cables of equal length. Maybe a short run to a project box then a 5 cable fanout from the box.

  17. Is it possible to make a VGA splitter using CAT-5? let’s say a 4 output VGA. If you were able to create one do you have a website that I can check for reference? And don’t you encounter any change on the picture quality?

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