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DIY USB Servo-Guided Water Gun

timothy posted more than 5 years ago | from the seasonally-inappropriate dept.

Toys 66

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!"

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66 comments

What? (0, Offtopic)

Eddi3 (1046882) | more than 5 years ago | (#26234065)

What is this? News for nerds? Stuff that matters?

Re:What? (5, Funny)

Anonymous Coward | more than 5 years ago | (#26234089)

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.

needs the right ammo (4, Funny)

AliasMarlowe (1042386) | more than 5 years ago | (#26234315)

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.

Re:needs the right ammo (1)

NetLarry (1439377) | more than 5 years ago | (#26236515)

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

Re:What? (2, Funny)

Anonymous Coward | more than 5 years ago | (#26234389)

vampire hoard

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

Re:What? (3, Funny)

spazdor (902907) | more than 5 years ago | (#26235977)

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.

Re:What? (1)

sakshale (598643) | more than 5 years ago | (#26235261)

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

USB != serial (0, Insightful)

Anonymous Coward | more than 5 years ago | (#26234069)

Since when USB port is synonym for serial port?

Re:USB != serial (4, Informative)

LS (57954) | more than 5 years ago | (#26234175)

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

Re:USB != serial (4, Funny)

Eddi3 (1046882) | more than 5 years ago | (#26234229)

Sexy?

Re:USB != serial (0)

Anonymous Coward | more than 5 years ago | (#26234539)

1. Add more degrees of freedom:
1.1 vibrate
1.2 to & fro
2. XXX
3. Squirt!

Re:USB != serial (0)

Anonymous Coward | more than 5 years ago | (#26234623)

(replying to self)
Um, should have looked at the image. Turns out it is a female squirter, so I need to refactor.

Re:USB != serial (0)

Anonymous Coward | more than 5 years ago | (#26234301)

Supercalifragilisticexpialidocious?

Re:USB != serial (0)

Anonymous Coward | more than 5 years ago | (#26240387)

Squirty???

Re:USB != serial (1)

Tony Hoyle (11698) | more than 5 years ago | (#26235079)

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).

Water? near the electronic equipment? (0)

Anonymous Coward | more than 5 years ago | (#26234073)

I don't fucking think so!

Re:Water? near the electronic equipment? (1)

Q-Hack! (37846) | more than 5 years ago | (#26236981)

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

Upgrades (0)

Anonymous Coward | more than 5 years ago | (#26234105)

Okay heavier servos, check.

Belt fed .50 caliber water cooled, check.

Improved laser assisted targeting system, check.

Okay, I'm ready for my tax audit now.

And if using a hard drive step motor? (1)

crazybit (918023) | more than 5 years ago | (#26234115)

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

Re:And if using a hard drive step motor? (1)

JuzzFunky (796384) | more than 5 years ago | (#26234281)

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 [letsmakerobots.com]

Re:And if using a hard drive step motor? (2, Interesting)

quitte (1098453) | more than 5 years ago | (#26234427)

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.

Re:And if using a hard drive step motor? (1)

mustafap (452510) | more than 5 years ago | (#26235877)

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.

Add motion detector (0)

Anonymous Coward | more than 5 years ago | (#26234121)

And now you've got something super marfa.

Microcontroller? (1)

Mozk (844858) | more than 5 years ago | (#26234123)

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

Re:Microcontroller? (5, Informative)

Mozk (844858) | more than 5 years ago | (#26234157)

Oh wait, nevermind, they're just trying to sell their kit. You might as well buy an Arduino [wikipedia.org] since it's cheaper and has more applications [arduino.cc] . 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 [arduino.cc] .

Re:Microcontroller? (0)

Anonymous Coward | more than 5 years ago | (#26235671)

...You might as well buy an Arduino [wikipedia.org] since it's cheaper and has more applications [arduino.cc] ....

Both are based on the Atmel Atmega series chips (currently atmega168, I believe.)

I have a Nerdkit (bought it for a small nagios project I'm working on), but from my reading and research, the big difference is that the Nerdkit is a microcontroller on a breadboard, meaning that you can make on-the-fly changes to your circuitry.

The Arduino is a put-together PCB with the mc chips pins wired to fixed pins on the board.

As far as comparison, the Arduino looks more professional, but you're working within their environment.

It's just a matter or preference. You get the same thing from both. I like working with basic nuts&bolts, so I prefer the Nerdkit setup. Others might prefer a more "plug and play" setup.

Re:Microcontroller? (1)

Detritus (11846) | more than 5 years ago | (#26234757)

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?

Re:Microcontroller? (1)

betterunixthanunix (980855) | more than 5 years ago | (#26235195)

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.

This is bad (2, Funny)

confused one (671304) | more than 5 years ago | (#26234201)

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!

Re:This is bad (1)

WarJolt (990309) | more than 5 years ago | (#26234213)

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

Person missed a scale up it could get bad. (0)

Anonymous Coward | more than 5 years ago | (#26234255)

Armies of real gun wielding robots face off with armies of robots with corrosive liquids.

Water swapped with a worse liquid. Disadvantage for armies of real gun wielding robots could be that the liquid the robots are using is normal on hand so they can rearm simpler.

Re:This is bad (2, Insightful)

hax0r_this (1073148) | more than 5 years ago | (#26234239)

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".

This whole thing is a plot by . . . (1)

PolygamousRanchKid (1290638) | more than 5 years ago | (#26234701)

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.

Re:This whole thing is a plot by . . . (1)

hesiod (111176) | more than 5 years ago | (#26235363)

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.

Re:This is bad (0)

Anonymous Coward | more than 5 years ago | (#26234871)

Who knew that typing 'import skynet' was a bad idea.

http://xkcd.com/521/

Re:This is bad (1)

Julz (9310) | more than 5 years ago | (#26247983)

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

Arduino (1, Insightful)

Anonymous Coward | more than 5 years ago | (#26234259)

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

I'm unfamiliar with that substance... (1, Funny)

acehole (174372) | more than 5 years ago | (#26234321)

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

 

Re:I'm unfamiliar with that substance... (0)

Anonymous Coward | more than 5 years ago | (#26234823)

It's like beer, only less so.

Re:I'm unfamiliar with that substance... (5, Funny)

Anonymous Coward | more than 5 years ago | (#26235155)

It's like beer, only less so.

Oh, so it's like American beer.

Re:I'm unfamiliar with that substance... (0)

Anonymous Coward | more than 5 years ago | (#26235431)

Even more less so, but in America at least it won't make you sick.

Re:I'm unfamiliar with that substance... (1, Funny)

Anonymous Coward | more than 5 years ago | (#26235699)

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.

A coincidence (1)

thegnu (557446) | more than 5 years ago | (#26242279)

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)

Re:I'm unfamiliar with that substance... (1)

tehcyder (746570) | more than 5 years ago | (#26257203)

Q: Why's Australian beer like making love in a canoe?

A: It's fucking close to water.

Come on, it's almost 2009 already (1)

Dachannien (617929) | more than 5 years ago | (#26234463)

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

Bang Bang (0)

Anonymous Coward | more than 5 years ago | (#26236095)

Is anyone else thinking this might become one of the most used tools for assassinations in the near future? With a decent projectile weapon and a built-in webcam, an innocuous seeming laptop could be the man on the grassy knoll.

USB = Universal Supply Bus (0)

Anonymous Coward | more than 5 years ago | (#26236235)

The real success of USB is as the universal source of a convenient five volts, with data as a secondary consideration. Look at all the buckets of incredibly weird crap you can get from China [made-in-china.com] - the USB Christmas trees [today.com] , the chicken foot flash drive [slashgear.com] , the mouse with a scorpion in [cecf.com.cn] ...

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

Re:USB = Universal Supply Bus (1)

thegnu (557446) | more than 5 years ago | (#26242295)

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!!!!

not a unique idea. (1)

Kaenneth (82978) | more than 5 years ago | (#26238105)

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.

HELP WITH USB (0, Offtopic)

charlie baba (1440057) | more than 5 years ago | (#26246855)

i got an mp3 player for Christmas. sony- charged by plugging into a usb port on the computer, great but don't want to redo the settings on my computer to charge the mp3 and don't want to spend $40 for a charger. so would like to know if i already have a spare power supply for a desk top computer could i wire up a usb port and use it to charge the mp3. i so on the net taco has a voltage suppresor to protect the mp3 from spikes, if i wire that in would that the all that is needed to set up my on seperate power supply? thanks for any and all comments.
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