Build your own water rocket launcher

We feel like the days when you want to play in the water are far behind us. But if you can still find a warm afternoon here or there this water rocket launcher build is a fun undertaking. We figure most of the time spent on the project will be in shopping for the parts. They’re all quite common, and once you have them on hand it can be assembled in under an hour.

The concept is simple, but that doesn’t stop people from building rather complicated water rocket rigs. This one which [Lou] devised is rather simple but it does offer connections to a hose and air compressor (the alternative being to fill the bottle with water ahead of time and use a bike pump for air pressure). PVC is used to connect the two inputs to the bottle via a pair of valves. The bottle is held in place while water and air are applied. The launch happens when a pull on that rope  releases the bottle.

Check out the build process and bottle launch after the break. We think that rocket needs a few fins.

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Watering system for your vegetable garden

The vegetables will be alive when [Dillon Nichols] returns from vacation thanks to this automatic watering controller that he built. This is the second iteration of the project, and deals mainly with replacing the electronics and UI of the controller itself. He detailed the hardware used for watering in a previous post. He plumbed in a solenoid valve with a hose threading on the output end for the soaker hoses snaking through the garden beds. This is a normally open valve but we’d suggest using a normally closed valve as a power outage will let the hose run continuously.

[Dillon] prototyped the design on an Arduino board, then moved to a standalone ATmega328 chip on some protoboard for the final design. He used a 3D printer to make the custom face plate which allows access to the three control buttons and provides a place for the character LCD to be mounted. In addition to the timer settings there is a manual watering switch as well. He used a typical mains light switch, wiring it with a pull-down resistor to make it work well with the Arduino. His explanation of the timer system can be seen after the break.

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Electric paint brush loads itself with paint

Meet [Jahangir Ahmad]. He’s a 19-year-old from India who recently won third place in a contest put on by the National Innovation Foundation. Here he’s posing with the electric paint brush which he developed after seeing some local painters struggling with brushes and buckets at the top of a ladder.

His system uses a 1 hp motor to pump paint from the bucket directly into the brush. Once it enters the handle a distributor splits the flow into four parts so that it reaches the bristles evenly. The pump of the paint is actuated by a controller which can be worn on the painter’s belt. When you get a little low on paint, just hit the button and you’ll get boost. Since the base of the bristles is meant to hold a small reservoir of paint, this has the potential to be better than dipping in a bucket.

[via Reddit via Home Harmonizing via Damn Geeky]

Automated hose keeps cats from watering you

Commenter [TheCreator] reminded us of this fantastic video from [Craig Turner] who you may recognize from SBS’s Top Gear Australia Video Competition.  You see, [Craig] has been struggling for some time with the problem of neighborhood cats relieving themselves pretty much all over his stuff. Through surveillance he identified (and named) around 9 separate cats sauntering into his yard during the wee hours of the night.  The only issue now was to humanely discourage them from entering his yard.

The best solution, in this case, was a simple spray from the garden hose, but who is going to stay up all night to watch for cats? [Craig]’s ’75 Galant happens to have aftermarket door locks. These typically contain a simple powerful 12V actuator that will push or pull when given current. The actuator is strong enough, and has enough travel, to depress your typical garden sprayer handle. The lock actuators even include enough mounting hardware to tack everything together.  The only irreversible part of the hack appears to be the hole drilled into the sprayer’s handle.

The job of cat detection is handled with a PIR sensor (sourced from his home security system) and a paper towel tube to narrow the detector’s field of view. Placed at animal height the PIR detector works like a trip line, and flips a relay connected to an array of devices:  A bright LED lamp, a DSLR set to take several quick photos of the victim, An HD video camera, and the sprayer solenoid.  This whole rig is placed at a convenient choke point and hilarity ensues! A schematic is included in the video but is pretty difficult to interpret, we transcribed it for you. Some details are unclear but essentially a few relays are stapled together to provide either high or low switching signals.

Check out the video, [Craig]’s schematic, and our interpretation of [Craig]’s schematic after the jump!

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Halloween props: puking pirate

With everyone’s favorite free-candy holiday approaching, [Slouriesr] set to work building a vomiting ghoul for his Halloween display. He’s calling it a puking pirate and it centers around a pump and some simple plumbing fixtures.

First, the vomit receptacle was made by adding a sink drain with a pop-up stopper to the bottom of a kitty litter bucket. The drain slows the evacuation of liquid into a five gallon bucket below. In that bucket you’ll find a float switch pump used to keep water off of a pool cover. As the bucket fills up the pump turns on and empties the water through a hose ending at the ghoul’s mouth. The result is a 20-second puke cycle sure to delight the trick-or-treaters. Sure, there’s a lot of work to be done to get this guy looking the part, but what a great idea!

Help keep us in the holiday spirit by sending the details on your latest prop build.