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DIY USB Servo-Guided Water Gun

Posted by timothy on from the seasonally-inappropriate dept.

An anonymous reader writes "What better way is there to learn something than by making your own DIY gadget? Here's a new video showing how to use a common hobby servo, in conjunction with a small water pump, to create a USB controlled water gun! You can use your keyboard to aim and fire at an unsuspecting passerby. Both fun and educational, this project looks like a great DIY weekend project for any IT guy, wanting to make sure people think twice before asking a stupid question!"

46 of 66 comments (clear)

  1. Re:What? by Anonymous Coward · · Score: 5, Funny

    Are you saying this doesn't matter? Legions of Wicked Witches will be stopped by this new weapon. Fill it with holy water and we may survive the vampire hoard.

    This is all that matters.

  2. And if using a hard drive step motor? by crazybit · · Score: 1

    anyone played with these things? would it be harder than the servo?.

    --
    - Human knowledge belongs to the world
    1. Re:And if using a hard drive step motor? by JuzzFunky · · Score: 1

      Modern Hard Drive motors are not steppers, although they do work in a similar way. Driving them is a more complex than driving a servo. Here's a good article of what's required: http://letsmakerobots.com

      --
      Unexpect the expected!
    2. Re:And if using a hard drive step motor? by quitte · · Score: 2, Interesting

      That's probably the worst brushless dc controller ever built. As you can see in the video the circuit cannot recover from too low rpm of the motor. He mentions better waveforms at the bottom of the site, though.
      A proper sensorless BLDC controller measures the back EMF at the undriven coils and uses that information to figure out which coils to drive. Also you don't need a common ground for the coils, instead the polarity should switch when both ends of a single coil have the same potential. Of course it's possible that each of the coils actually has a third contact in the middle.
      Properly driving a sensorless bldc motor is quite an interesting challenge for microcontroller programming. You'd need the analogue input and 3 PWM channels. Probably 3 digital outputs, too to switch the polarity.
      In other words: I'm taking apart a harddrive right now.

    3. Re:And if using a hard drive step motor? by mustafap · · Score: 1

      Very much so. The hobby servo is one of the simplest devices to hook up to a microcontroller. It will run at 5v, and takes a 5v pulse to position it. The pinouts are very easy to find on the web, as is the software. I have my own code, which I'll publish if there is enough interest.

      --
      Open Source Drum Kit, LPLC deve board - mjhdesigns.com
  3. Microcontroller? by Mozk · · Score: 1

    I don't see why a microcontroller is necessary for this. There are much simpler and cheaper ICs to control servos.

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    No existe.
    1. Re:Microcontroller? by Mozk · · Score: 5, Informative

      Oh wait, nevermind, they're just trying to sell their kit. You might as well buy an Arduino since it's cheaper and has more applications. The only thing it lacks compared to the other is an LCD screen, but I figure it makes up for it by having a big community.

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      No existe.
    2. Re:Microcontroller? by Detritus · · Score: 1

      How do you learn something about the technology if you just buy some generic servo transmitter chip? Why bother buying another chip if the microcontroller can do the job?

      --
      Mea navis aericumbens anguillis abundat
    3. Re:Microcontroller? by betterunixthanunix · · Score: 1

      If it is a con with DSP hardware, it might be interesting to attach an ultrasound SONAR or IRDAR detection mechanism to it, and create a control system that automatically tracks targets. We did something similar in a robotics class once, but it was Lego mindstorms and the tracking was pitiful, because instead of using DSP we just had a simple nonlinear filter in software (if the signal increases when turning left, turn more until the signal decreases); better hardware should yield better results. The watergun part would make for a really cool demonstration for your child's show-and-tell.

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      Palm trees and 8
  4. Re:USB != serial by LS · · Score: 4, Informative

    whaddya think the "S" in USB stands fer, huh?

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    There is a fine line between being a cultivated citizen and being someone else's crop. - A. J. Patrick Liszkie
  5. This is bad by confused+one · · Score: 2, Funny

    Can't you see... If one person builds one, then another will have to build one as well to defend themself. And, so, it escalates. Then comes the larger more powerful water gun. Then the mobile water gun. Then a brilliant but misguided developer creates an artificial intelligence. Building such a weapon will ultimately lead to IT armageddon. Think of the children!

    1. Re:This is bad by WarJolt · · Score: 1

      We'll just get the armies real gun wielding robot's to take out the water cannons. I think our IT is safe.

    2. Re:This is bad by hax0r_this · · Score: 2, Insightful

      Umm... more to the point, its a water gun. Am I the only one who doesn't want a water gun by my computer?

      On the other hand, just today I was contemplating building a servo mounted nerf gun, that would seem to be more appropriate for use by an "IT guy".

    3. Re:This is bad by 64Bit · · Score: 1

      We must close the water gun gap!

    4. Re:This is bad by Julz · · Score: 1

      I'm sure this would benefit from a webcam and a page with controls :)

      --
      When shit hits the fan get some of these https://youtu.be/pY-GncsZ-UE
  6. Re:USB != serial by Eddi3 · · Score: 4, Funny

    Sexy?

  7. Arduino by Anonymous Coward · · Score: 1, Insightful

    This would have been easier and cleaner to do with an Arduino

  8. needs the right ammo by AliasMarlowe · · Score: 4, Funny

    Fill it with holy water

    Kids today are not evil enough. Fill it with a mix of 3-methyl-1-butanethiol, 2-quinolinemethanethiol, or similar mercaptans (http://en.wikipedia.org/wiki/Skunk#Anal_scent_glands). Even using a dilute solution, your victim will have no friends for a week.

    It might even keep the kids off your lawn.

    --
    Those who can make you believe absurdities can make you commit atrocities. - Voltaire
    1. Re:needs the right ammo by NetLarry · · Score: 1

      I did the 3-methyl-1-butanethiol trick >30 years ago at college. One drop discouraged even the most determined male dog trying to get in my house to "service" my in-heat female collie. There were a lot of clean & fluffy male dogs in the neighborhood after visiting my yard. My 5 ml bottle went a LONG way - lasted for years. Note: Don't keep the bottle in the house; once you open it the aroma will linger wherever you store it. NetLarry

  9. I'm unfamiliar with that substance... by acehole · · Score: 1, Funny

    Wwwwat-er? Apparently wiki says that its a naturally occurring substance that people 'drink' and do something called 'wash' with.

     

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    Be you Admins? nay, we are but lusers!
    1. Re:I'm unfamiliar with that substance... by Anonymous Coward · · Score: 5, Funny

      It's like beer, only less so.

      Oh, so it's like American beer.

    2. Re:I'm unfamiliar with that substance... by Anonymous Coward · · Score: 1, Funny

      Oh, so it's like American beer.

      My favorite old Aussie joke:

      Q. Why do Americans like their beer freezing cold?

      A. So you can tell it from piss.

    3. Re:I'm unfamiliar with that substance... by tehcyder · · Score: 1
      Q: Why's Australian beer like making love in a canoe?

      A: It's fucking close to water.

      --
      To have a right to do a thing is not at all the same as to be right in doing it
  10. Been there, seen that, got wet... by MRe_nl · · Score: 1

    And for the larger, internet-controlled version, 3 years ago, visit
    http://www.robob.nl/node/33

    --
    "Kill 'em all and let Root sort 'em out"
  11. Re:What? by Anonymous Coward · · Score: 2, Funny

    vampire hoard

    Are you suggesting there is someone out there stockpiling vampires in case of a vampire shortage?

  12. Come on, it's almost 2009 already by Dachannien · · Score: 1

    USB's already been added to everything possible. Shouldn't this thing have Bluetooth?

  13. Re:USB != serial by bigstrat2003 · · Score: 1

    Scandalous!

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    "16MB (fuck off, MiB fascists)" - The Mighty Buzzard
  14. USB = Univeral Serial Bus by DigitalReverend · · Score: 1

    http://en.wikipedia.org/wiki/USB

    --
    I read Slashdot for the headlines, because the headlines, unlike the articles, are usually original and never duplicated
  15. Re:USB != serial by HiVizDiver · · Score: 1

    You owe me a new monitor and keyboard.

  16. This whole thing is a plot by . . . by PolygamousRanchKid+ · · Score: 1

    Umm... more to the point, its a water gun. Am I the only one who doesn't want a water gun by my computer?

    . . . PC Companies!

    A squirt-gun-damaged, shorted-out PC probably isn't covered by the warranty.

    Time to buy a new one.

    --
    Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
    1. Re:This whole thing is a plot by . . . by hesiod · · Score: 1

      Umm... more to the point, its a water gun. Am I the only one who doesn't want a water gun by my computer?

      . . . PC Companies!

      Actually, they probably like the idea... then they can sell you another computer.

  17. WTF? by hack++slash · · Score: 2, Insightful

    Surely this stuff should be on the idle section of slashdot!

    If I want DIY servo controlled stuff I can go to http://www.hackaday.com/ or http://www.hackedgadgets.com/ or http://www.hacknmod.com/ or even http://www.instructables.com/

    --
    To do something right, you often have to roll up your sleeves and get busy.
  18. Water and Electronics != Profit by Anonymous+Codger · · Score: 1

    Does anyone else think that maybe firing squirt guns around computers is less than a brilliant idea?

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    No sig? Sigh...
    1. Re:Water and Electronics != Profit by pegdhcp · · Score: 1

      Nope, especially if you use CFC...

  19. Re:USB != serial by Tony+Hoyle · · Score: 1

    Yeah at no point do they say USB - which would be a more complex project (although I guess USB serial controllers are fairly cheap these days).

  20. Re:What? by sakshale · · Score: 1

    I'm thinking about CAT control.... Let that critter try to sleep on my computer when I'm at work.... Yes!

    --
    For every problem there is a solution that is simple, obvious and wrong.
  21. Re:USB != serial by Hillgiant · · Score: 1

    schadenfreude?

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  22. Hmm... by Locke2005 · · Score: 1

    Water and electricity in close proximity in a jury-rigged device... what could possibly go wrong?

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    I've abandoned my search for truth; now I'm just looking for some useful delusions.
  23. Hoarding a horde? by macraig · · Score: 1

    What, you think someone is hoarding a horde of vampires? Who? Bruce Campbell?

  24. Re:What? by spazdor · · Score: 3, Funny

    No. Absolutely not. Nobody is doing that.

    Completely unrelatedly, does anyone know if butchers will deliver blood directly to your basement? I'm never quite sure how to ask.

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    DRM: Terminator crops for your mind!
  25. Re:USB ?= serial by Gible · · Score: 1

    ...except in the first paragraph...

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    ~/ One man's opinions is a lifetime of pain. /~
  26. Re:Water? near the electronic equipment? by Q-Hack! · · Score: 1

    If you haven't yet water cooled your computer, then we must revoke your geek status.

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    Some days I get the sinking feeling Orwell was an optimist.
  27. not a unique idea. by Kaenneth · · Score: 1

    A fully automatic water sentry turret for the dining room table, out of lego mindstorms NXT

    If a cat gets shooed off a table whenever a human is around, they only learn to stay off the tab;e when a human is around.

  28. A coincidence by thegnu · · Score: 1

    Oh, so it's like American beer.

    My favorite old Aussie joke:

    Q. Why do Americans like their beer freezing cold?

    A. So you can tell it from piss.

    We likewise have a joke about you guys and your taste in beer:

    Fosters: Australian for beer :)

    (I am aware you guys export it more than you drink it)

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    Please stop stalking me, bro.
  29. Re:USB = Universal Supply Bus by thegnu · · Score: 1

    USB 3.0 plans to take the voltage down to 4 volts. This move must be resisted at all costs!

    For one, I want to be able to power a 5400rpm laptop HDD off only USB power, and you can't do that on 5v. Or was that an amperage problem. I don't remember.

    The point is, I'M DISSATISIFIED!!!!

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    Please stop stalking me, bro.
  30. water guns and computers? by sepelester · · Score: 1

    Am I really the first one to point out that they don't mix??