Hopefully Detect Trolls Before They Devour You

In the cold and mysterious wilderness of Norway, it pays to be ready for anything–especially heavy-walking trolls. The team at [nullohm] decided to prepare thoroughly for their trek into the woods to witness the Leonids meteor shower by putting together an Arduino-based “troll detector”.

The device is based on the superstition of hammering a steel spike into a tree to keep trolls away from camp. This goes one step further by including an accelerometer and LED indicators so that you can tell exactly what type of troll is just about to feast upon your tender human flesh.

When the detector is installed into a nearby tree, it takes an average seismic measurement and then looks for telltale footfalls. Even if you’re not concerned with perpetuating superstitions, you might find a use for the source code for simple seismic activity monitoring at home to supplement your miniature seismic reflector.


  1. jeff-o says:

    I wonder how they tested it? With elephants?

  2. Daid says:

    With trolls of course, the internet is full of them. Shouldn’t be any problem.

  3. jeff-o says:

    That makes sense.

    Actually, this could be useful as an intrusion detector, assuming it’s sensitive enough to detect the footfalls of humans as well as trolls.

  4. Zork says:

    You have been eaten by a grue.

  5. Chris says:

    Seismic sensors have been used for intrusion detection at secure sites for years now.

  6. squidarthur says:

    funny, inventive and practically useless. In other words, a great hack.

    That’s not what ‘hopefully’ means, though.

  7. RadBrad says:

    Grendel will no longer have the element of surprise. Nice hack!


  8. Digital says:


    priceless. just priceless!

  9. BiOzZ says:

    i find it fun when superstition hits science XD

  10. James says:

    Probably find that its not steel, so much as iron. Specifically cold iron, as most fae are negatively affected by it.

  11. Necromant says:

    Woah,nowteyjust nedd tohookit to wordpress to detect internet trolls as well.

  12. Necromant says:

    Ooops, looks like my keyboard’s dead.
    I meant “Now they just need to hook it to wordpress to detect trolls in comments. “

  13. Eirinn says:

    @Necromant a better alternative allready exists, it’s called Stupid Filter, google it :oP

  14. PR0CR4571N4T0R says:

    1) Is this HAD post trollbait?

    2) Are accelerometers really that sensitive to seismic activity? (ie, from the earths movements. not someone stomping near a tree)
    Obviously not. so right, this thing will indicate the direction of a tresspasser? how will it do this when the tree can only move side-to-side?

    Are there other models more precise for this purpose?

    3) Are people from norway really that superstitious? [read: stupidstitious]

    4) This isnt really a hack, is it?

    5) HAD Editors, leave out all the bullshit from a post and get to the point.

  15. PR0CR4571N4T0R says:

    6) Your site crashed my firefox session. granted, i wasnt missing much anyway was i.

  16. absolutezero says:


    7) waaaaaaaa


    Thanks for the hilarious post! I needed a good laugh :)

  17. Mane says:

    I also wonder how’d they calibrate the thing? Can you get the data from telltales? Now that would be a nice hack :)


  18. strider_mt2k says:

    Hmmm. Neat project!
    yeah you need a Grue detector/repeller.

    On a side note I wasn’t aware of the superstition, but it DOES explain why I’ve seen railroad spikes driven into trees where I’ve camped in the past.

    Generally I’m not superstitious, just extrastitous.

  19. Necromant says:

    @Eirinn Thanks, nice project. However newbies are not trolls. And I guess it will take more than bayes filtering to detect ‘thin’ trolls posts.

  20. Philip says:

    Another good hack will be a machine that fires railroad spikes into trees.

  21. Will says:

    FINALLY A DEVICE THAT WILL TAKE CARE OF o wait…oops nope internet trolls are not taken care of fail owell NOW A DEVICETHAT WILL KEEP THose TrOLLS OUT OF MY kITCHEN YES!!!!!!!!!!!!!!

  22. Will says:

    O fail my keyboard is messing up owell thats wat u get for a 1999 USB apple keyboard

  23. DanteUseless says:


    3) http://www.youtube.com/watch?v=e4PGFODxiJc (The Troll Hunter – Official Trailer)

  24. Ketin says:

    Just make sure Dethklok is not in town making an apology and you should be fine.

    For those not in the know: Dethklok is a fictional metal band that visits Finland in one episode to apologize for the country being destroyed by riots during their last tour. None of them are any good at speaking, so they make a song for it using lyrics from the countries book of necronamics. They awaken the Kraken which proceeds to destroy the country again.

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