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Build Your Own 10Mbit/sec Optical Data Link

Posted by timothy on from the neighbornet dept.

redcliffe writes: "This website has complete plans to build a 10 megabit per second optical data link that can work over up to 1 kilometre. It uses fairly cheap components, such as standard LED's instead of laser diodes. This also makes it a lot safer to work with, i.e. you won't burn your eyes out if you accidently look into it."

5 of 145 comments (clear)

  1. Re:Why not 802.11b? by laserjet · · Score: 5, Insightful

    You have a good point, and 802.11b probably would make sense in most conditions. The only benefits that this would offer you are 1) if you work in an area that has too much RF interference for 802.11b to work correctly, and 2) this would be more secure that 802.11b. For instance if you want to run a connection to your neighbor across the street, to intercept your connection, someone would have to get exactly in line with the transceiver, whereas 802.11b is broadcast all over the place.

    Aside from that, it just looks like they built it because they could, and that, is reason enough.

    --
    Moon Macrosystems. Sun's biggest competitor.
  2. My favorite warning sticker by shoppa · · Score: 5, Funny
    i.e. you won't burn your eyes out if you accidently look into it.

    Reminds me of my favorite warning sticker:

    Warning: Do not look directly into laser with remaining good eye
    Despite how effective the sticker was at reminding us to keep our goggles on, the safety people made us take it down.
  3. Got AUI? by Uller-RM · · Score: 5, Informative

    Has anyone else bothered to read this enough to notice that it will not work with twisted pair Ethernet? It requires an AUI connection. They even say in the FAQ, redesigning it to work with TP would be a pain in the arse.

    In order to use the circuit, you have to either buy an AUI->TP transciever, or set up a bridging machine.

    Just saving a bit of time for some people who are no doubt running out to Ripoff Shack grabbing l33t bl00 leds.

    1. Re:Got AUI? by Uller-RM · · Score: 5, Informative

      Ethernet over TP implements a link integrity signal. AUI does not. That's the main barrier to using this particular rig - you'd have to come up with an emulator for that signal, or the cards would refuse to transmit.

      (And FYI, you're partly right. Ethernet over TP uses Manchester encoding, which means that it watches for changes in logic rather than states - i.e. transitioning from ground to 5V is a 0, and 5V to ground is a 1. Hard drives actually also use this method.)

  4. Re:Sigh... by dattaway · · Score: 5, Informative

    I wish this were true. Many years ago, I was fascinated by lasers; unfortunately, infrared isn't too visible. Several years later, I now have dark stuff floating around in my eyes. For a person 33 years of age, I would not recommend looking at concentrated sources of energy, no matter how small.

    It may be a milliwatt, but its still heat: focused smaller than the head of a pin. It may burn. Damage in the eyes shows up many years later.