5 Foot Long PATA Cable From Cat5e


Not one to be constrained by specifications, Montac decided to construct an ATA cable that was well over the 18 inch maximum length.  PATA cables use 80 conductor wire, even though they only have 40 pin connectors. The extra 40 lines are all tied to ground. The cable was constructed from 10 pieces of Cat5e with one line from each twisted pair going to ground. The construction is as tedious as it sounds and at each end there are a few signal lines that also need to be pulled to ground. Once the cable was finished with heat-shrink tubing it was tested. The cable performed as well as, if not slightly better than the standard cables.

[thanks Luke Skaff]

22 thoughts on “5 Foot Long PATA Cable From Cat5e

  1. Very nice looking final product. I know how hard it is to make those cables line up and match nicely since I have made a few for driving LCD displays. I notice that you mention the cross talk benefits of the twisted paid design. Have you tried it with simple flat ribbon cable and it didn’t work? I find that most specs have lots of wiggle room. I wonder how far it could be pushed before errors start to occur. :)

  2. wow, that guy is insane!
    I don’t see why put the grounds in a idc connector instead of just soldering them directly together, it seems like the etra conector would just be a source of problems in the future.

  3. you are going to run into priblems in the long run using solid copper wire, first idc connectors are not designed for solid wire, and it will get brittle and the connections will become intermitant.

  4. It always amazes me how many people use UTP cables for things that are not balanced signals. I’m guessing that it dosen’t effect IDE cables too much (since they aren’t shielded anyway), but still…

    A shielded IDE cable would be pretty intresting. There’s quite a bit of electrical interference in a computer case (for example, sound cards are only going to get so good w/ DAC’s in the case because of interference).

  5. catV is cheap (or free), i think its a good project… you can find catV cable w/ stranged wires. this may have been a better choice. I wonder if the pata standard is 18″ due to crosstalk issues/interferance, or if its signal loss on the cable… I would lean toward noise. I’m sure a steel braid around it and ferite beads on each end could help out a lot as well.

    Possible applications?… Carputer dvdrom comes to mind… though I’d probably use a ide->usb adapter and make my long run w/ a usb exension…

  6. Nice work!

    The length specs aren’t really arbitrary; they depend on the quality of the cable.

    Two tests I’d do to verify the cable:
    1. Look at the “Eye pattern” with an oscilliscope. Make sure that the signals on the data lines are transitioning cleanly from 0 to 1 and back, without too much delay and without a lot of ringing. Do this for all channels.
    2. Look at the skew. The signal might be faster on some wires than others — this requires a logic analyzer to measure well, or at least a two channel scope. Compare the transition on each data line with the clock’s transition.

    Most importantly, though (and easiest) would be to see if the ATA protocol has a good checksum in it — if so, the data integrity should hold even if it has to re-try. Still, there could be a certain data pattern from a critical file that causes and error every time.. that would really suck.

    Overall, nice work!

  7. I’m not very suprised at the results; twisted pair after all should smoke having ground-signal-ground ribbon cables, due to the reduction in EM noise. Cat5e is unshielded twisted pair (UTP). I wonder what effect shielded twisted pair (STP) would have…

    Wouldn’t it be better to try this with SATA drives? Fewer wires, faster speeds after all. Whats the max length for SATA?

  8. Is there anything cat 5 cable can’t do?

    I use it for hanging pictures as well as anytime I need some wire and am in a pinch since I have gobs of the stuff from surplus. Hell you could even weave yourself a cat5 basket if you wanted.

    I vote for cat 5 cable or just any twisted pair copper to be put up next to duct tape in usefullness.

  9. #15: I second your vote. I bought 1000′ of cat5e a few years back for $40. In addition to its regular purpose, I’ve used it for who knows how many things. Makes a good speaker wire or for electronics wiring. Hell I’ve even used it to tie up an old futon mattress I was getting rid of :)

  10. 14

    I once heard of someone wanting to make their own SATA cables on a modding forum but the idea was shot down when another person started talking about SATA having a separation in the conductors for preventing crosstalk and such. So I dont know how much twisting would help distance specs if you need to keep the wires a fair distance apart.

  11. #14 – As far as I remember, max length is 1 m (~39″), max for eSATA is 2 m I believe.

    #15 – Yeah, I know exactly what you mean. I’m the “cable guy” at work (make cables for whomever needs them), so I always have a ton of it lying around. Any time I need to tie a bundle of wires together or anything like that, I just use a piece of cat 5 (or just one twisted pair if the application requires a tight knot). I once even braided the blue, orange, and green pairs into a bracelet for my girlfriend once.

  12. I once tried to make a USB cable from CAT5. Didn’t work at all. Not sure why…

    As for SATA cables, the separation might be in there because the wires aren’t twisted inside the cable (I think). Use twisted wires with one of each pair grounded, and the separation might be unnecessary. Notice I said “might.” :-)

  13. Wow! It never ceases to amaze me how the web works. :-) I designed that cable and wrote that article years ago!!! It works/works fine still toda, but I’ve learned a lot since then. i’d make a lot simpler design now. (I just had to see what caused a 2000% jump in my daily bandwidth usage!) LOL! Mabe y’all would like to see my upcoming articles on building out a Wi-Fi PTP system… Now THAT’s gonna be sweet.

  14. Back in the day, I was building an installation piece that involved a number of Barbie-cams – terrible little digicams almost-but-not-quite conformed to the RS-232 spec. Only problem was the 40ish foot cable runs that we needed. High-quality serial cables crapped out at around 10 feet, so I decided to wire up one using cat5. Worked a charm.

    Having half the team sitting there soldering up cameras was not that fun, though.


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