December 22, 2011
The scarecrow of death

(Or, my thoughts and advice about being a tinkerer.)

Before my girlfriend and I moved in together, she called me on one occasion to inform me that raccoons had turned the small fenced in garbage area next to her rented home into a horrifying pit of bad smells and despair. I can’t be sure how most people would have handled that situation but my first thought was, what can I build to solve this problem.

The solution that I came up with was what I call a water scarecrow, you hook a hose up to it and plug it in, then point it at an area you want to rid of racoons. When they trip the motion sensor, they get a blast of water. However, the design is badly flawed because there’s high voltage and water tubes and valves in the same cramped space. So beware, this project is not the most sophisticated or notable DIY project; nor is this article a detailed technical document on how to recreate my device. (You shouldn’t it’s dangerous). If you’re hoping for a more technical, advanced or interesting project try Hack-A-Day , or even some of my other write-ups: web based LED Matrix drawing application for Lol Shield, mostly from scratch mp3 player. This article is about a “good idea/bad implementation” example of DIY’ing and hopefully some good pearls of wisdom for people just starting out.

Lesson number one; with an important qualifier:

Don’t reinvent the wheel, unless you specifically intend to for the purposes of learning.

On the left is the machine that I devised to scare away the impolite, nocturnal creatures that were pestering my girlfriend. To the right is a small, relatively cheap, commercially available product with the exact same intended purpose. A friend sent me a link to the commercial version after I told him about my awesome, “totally original” idea.

The water scarecrow of death

I wasn’t really trying to solve a straight-forward problem, my true intention was to start an off-shoot style of steam-punk called back-yard-garden-punk.

ScareCrow (TM, I'm sure)

The fabulous Contech ® TM © brand ScareCrow TM ® ©

I’m not suggesting that you always buy a commercial product instead of making it yourself. But do consider at least googling. It’s possible and even likely that someone has built something that you intend to make; Don’t be disheartened. Finding a product or another builder’s project is a great place to start.

  • Is the commercial product ridiculously cheap, simple and the reviews are great? Consider just buying it and spending your energies elsewhere, this may be a well solved problem.
  • Is every example that you find flawed in your opinion, but you have a good idea on how to improve them? Great! Now you have the chance to learn from others mistakes instead of your own.
  • Were you already planning on building something that has been well engineered for a long time? In that case, do plenty of research and get as much knowledge as you can before you even pick up a tool. Don’t be scared to go this route, the worst thing that could happen is you’ll learn something new and the best case being that if you’re a little lucky and really smart you’ll discover something new.

Lesson number two:

Don’t use anything that comes from here: Electrical outlet for your projects until you’re certain you understand the risks.

Don’t fret, even if you’re not an electrician, you can still use electrons to make your machine think or move. To be more specific, always have a commercially built and tested device between you and the 220 AC voltage that comes out of your wall socket. For many of the things you might build, you can safely distance yourself from dangerous types of electrical current. Converters will turn an AC voltage into manageable voltage and wattages, don’t test that with your tongue, but you’re unlikely to die from a 9 volt DC wall-wart. Even if your machine needs a lot of power you can more safely control it with a power-switch tail like this one from adafruit:

Back to my water scarecrow, here’s  what *not* to do with 220 volts. Don’t run it through an electrical junction box inside the same container as a cheap, unreliable water valve intended for backyard irrigation, like this:

Electrical junction box

Should I cut the *red* wire.. or the *blue* wire?!


Is there a government conspiracy to electrocute average citizens? Tune in to this weeks episode of: Automation Autopsy (on the History channel)

Lesson three:

Don’t throw out the baby with the bathwater.

Ultimately, because of the dangerous nature of the device, I never put it into action. I *did* however learn a few valuable lessons and came up with one or two good ideas, even from such a silly, simple project. Often times neat things get built but with littler or no thought about the overall casing. In this instance though, besides the dubious safety risk of having high voltage next to a cheap water valve, the project itself was held together well with a small rubbermaid garbage can. A small, wooden board with metal brackets held the inner assembly together while the pipes that conveyed water to the target also firmly held the contraption’s innards inside the trash can.

Movement sensor

This is what HAL 9000 would have looked like if engineered by rednecks.

The trash can itself was sturdy but also easily cuttable, making a great platform for mounting the sensor. The sensor itself was a standard wall switch with a motion sensor instead of a tactile, flip switch. A rectangular hole let the switch and sensor assembly protrude, along with two screw holes  to allow it to be fastened.

I also used some materials a bit creatively to allow an indicator lamp to shine through a transparent piece of plastic. The plastic is a tupperware bowl, hot-glued to the trash can for a water-tight connection. See, I was thinking about water safety from the outside in… just not the apocalyptic possibility of catastrophic water valve failure.

The indicator lamp

Hot glue guns aren’t just for doing sissy arts and crafts, you can also ruin tupperware with it.

Finally, for many devices that have cords going to them, longevity of the cord attachment is an issue. For many commercial devices, zig-zagging rubber pieces allow the attached cord to flex but also hold it in place so that the soldered wires aren’t under stress. Here, I came up with a fairly good DIY solution that uses two zip-ties, and a zip-tie fastener. One large hold allows the cord through, while a smaller hole allows a zip tie to be tied to the casing. That zip tie is then tied to a round fastening piece connected to the cord. In this way, the cord is allowed to move freely, whichever way it’s pulled, but is on a ‘leash’ so that the connection points of the wires are never stressed.

Zip-tie cord management

NO, I am not interested in being a hand model for your place of business, please stop sending me emails.

Here we are at the conclusion part of the article. Most importantly, consider you safety when you’re building stuff. Don’t make the project you just read about, it’s dangerous. If you have to sacrifice your life for a project, please consider making it a pretty rad project.

So far, though, the best advice I can give to anyone interested in being a tinkerer, maker or DIY’er would be to write about and share your work. If you’ve got a fairly thick skin, you’ll get great feedback by publicly posting your experiences.

Seriously, go ahead and write about it on the net. Most would agree that it’s a better use of blogs than writing about the breakfast you ate, it’s free to do if you already own an internet connection and a computer; and you’re more likely to meet other like minded individuals, especially if you live in a small town.

Here’s a few places to get started:

Once you’ve written about your project (add pictures too, they tell thousands of words), try submitting some of your write-ups to popular maker/DIY and aggregation sites! Prepare yourself for the resulting criticism that will result. Here’s a basic guide on how to use the three main forms of criticism:

  • Look for and heed the constructive criticism well. Don’t take things personally here, no-one is perfect and if you listen to someone with more experience you’ll learn and improve faster than personal trial and error alone.
  • Ignore the negative, If someone starts a comment with, “You’ve got too much time on your hands”, don’t bother reading the rest of it.
  • Find a local printing business to print out the purely fluff, positive comments and fashion them into a glorious, ego-maniacal wallpaper for your house.

Good luck! Thanks for reading :)

P.S. In case you’re interested, my water scarecrow of death did actually work, as evidenced by this haunting video, wherein I almost accidentally murdered my entire neighborhood by way of shoddy electrical safety practices.


Hey thanks for reading this far! Maybe you'll be interested in more of my projects? Check out my homepage :)


  1. Amit Kumar
    Posted Dec 22 at 9:19 pm | Permalink

    So, what is the deadly part?

  2. Anonymous
    Posted Dec 22 at 9:23 pm | Permalink

    Unfortunately, nothing awesome like radiation or a flame-thrower. 

    “However, the design is badly flawed because there’s high voltage and water tubes and valves in the same cramped space.”

    “Back to my water scarecrow, here’s  what *not* to do with 220 volts. Don’t run it through an electrical junction box inside the same container as a cheap, unreliable water valve intended for backyard irrigation, like this:”

  3. Anonymous
    Posted Dec 23 at 2:46 pm | Permalink

    Unknown contributor ~> Wheres your ideas and ambition are within the realm of Tesla, even the best of us make mistakes. Success encourages arrogance, while failure breeds humility. A sense of humor is what gives us the ability to carry on and I wish you great success in your future endeavors…  I think they are very worthy!

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