Sitting on the beach, finishing off a beer one day, [Rulof] realized that if he put a motor in the beer bottle with a propeller at the bottle’s mouth, he could attach the result to his leg and use it to propel himself through the water. Even without the added bonus of the beautiful Mediterranean waters through which he propels himself, this is one hack we all wish we’d thought of.
These particular beer bottles were aluminum, making cutting them open to put the motor inside easy to do using his angle grinder. And [Rulof] made good use of that grinder because not only did he use it to round out parts of the motor mounting bracket and to cut a piston housing, he also used the grinder to cut up some old sneakers on which he mounted the bottles.
You might wonder where the pistons come into play. He didn’t actually use the whole pistons but just a part of their housing and the shaft that extends out of them. That’s because where the shaft emerges from the housing has a water tight seal. And as you can see from the video below, the seal works well in the shallow waters in which he swims.
Continue reading “Leg Mounted Beer Bottles for Underwater Propulsion”
This laser-cut lamp is an awesome example of what you can do with a laser cutter and a bit of creativity. It was completely laser cut and features no fasteners, except for a bit of glue.
[PaisleyGarbage] has been making lamps for a while now and had the concept for this one early on. After rendering a model of it on the computer, he decided it was finally time to try making it. It wasn’t quite as easy as he thought it’d be, but the challenges along the way only help you to learn when doing a project like this.
He laser cut alternating strips of wood and acrylic to create the unique sandwiched light look of the final product. Instead of using fasteners or anything, he even slid the pieces together on acrylic dowels keeping the design as minimalist and clean as possible. But the part we really like is the magnetic switch.
Continue reading “Laser-Cut Lamp With Magic Switch”
Messing with the U.S. Mail is not something we generally recommend. But if you build your own mailbox like [Bob] did, you stand a much better chance of doing what you want without throwing up any flags.
Speaking of throwing up flags, one of the coolest parts of this project is the toy mailbox inside the house that monitors the activity of the real box. When there is mail waiting, the flag on the toy mailbox goes up. Once [Bob] retrieves the mail, the flag goes back down automatically. A magnet in the real box’s flag prevents false alarms on the toy box provided the Flag Raised On Outgoing protocol is followed. Best of all, he built in some distress handling: If the mailbox door is left hanging open or the battery is low, the toy mailbox waves its flag up and down.
So, where do the three sensors come in? A magnetic reed switch on the wall of the real mailbox pairs with a magnet in the flag. To determine whether the door is open, [Bob] initially used another magnetic reed switch on the underside of the box. This didn’t work well in wet weather, so he switched to a mechanical tilt sensor. An IR LED on the ceiling and a phototransistor on the floor of the box work together to detect the presence of mail.
[Bob]’s homebrew mailbox has a false back that hides a PIC 16F1825. When the door opens, the PIC wakes up, turns on a MOSFET, and checks the battery level. It waits two minutes for the mailman to do his job and then reads the flag state. After comparing the IR LED and phototransistor’s states, it sends a message to the toy mailbox indicating the presence or absence of mail.
The toy mailbox holds a modified receiver board and a servo to control its flag. [Bob] has made the code and schematics available on his site. Walk-through video is after the jump.
Continue reading “Triple Sensor Mailbox Alert Really Delivers”
[Dave] wanted to make an Arduino robot out of a remote-control 1950 Mercury. He removed the RC portion from the car and kept the drive and steering motors. The idea was to use three ultrasonic rangefinders in the grille real estate and move the car forward based on the longest distance detected.
He initially used a Seeed motor controller and some Grove cables soldered to his sensors to power the steering. It went forward, but only forward, and [Dave] decided the motor controller and the car’s steering motor weren’t playing well together.
[Dave] had the idea to use relays instead to both power the motor and determine polarity. Now, the Merc was turning and avoid obstacles about half the time, but it was also getting dinged up from hitting walls. He figured out that his sensor arrangement was making the car turn immediately and decided to give the program information from the wheels with a reed switch and a rare earth magnet. The only problem is that the caliber of magnet required to trip the reed switch is too heavy and strong. [Dave] and has concluded that he simply can’t exercise the kind of control over the car that he needs. and will build his own robot chassis.
Update: Check out a video of [Dave]’s car after the break.
Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.
Continue reading “Fail of the Week: Robotic 1950 Mercury Boogies, Won’t Come Back From Dead Man’s Curve”
It takes a lot of power and energy to keep grass levels down to an appropriate level; especially when it’s hot out. If cool glasses of lemonade aren’t around, the task at hand may not be completed any time soon causing the unkempt blades of green (or yellow) vegetation outside to continue their path of growth towards the sun.
Instead of braving the oven-like temperatures which will inevitably drench the person in sweat, this solar powered robot has been created ready to take on the job. With the heart of an Arduino, this device shaves down the grass on a regular basis, rather than only chopping down the material when it gets too long. This helps to save electricity since the mower is only dealing with young and soft plants whose heads are easily lopped off without much effort.
Internally, the robot’s circuitry interfaces with an underground wiring system that defines the cutting zones within the lawn, and proves to be a simple, accurate, and reliable approach to directing the robot where to go. If the device travels under a shaded area, a battery kicks in supplying energy to the engine. When sunlight is available, that same battery accumulates the electricity, storing it for later.
Continue reading “Solar Powered Lawn Mower Cuts the Grass So You Don’t Have To”
[Rhys] wanted to secure his home against burglars, but didn’t want to go the normal route of using those bulky plastic magnet and reed switch deals. So he sourced some glass reed switches and made his own completely hidden security system.
By using small glass reed switches [Rhys] was able to mount them flush to the wood paneling just above the window frames. To do this he drilled and then chiseled two slots for the reed switches to go in, with the wires routed into the house. A bit of bondo or drywall filler and some paint later and they are completely invisible! To finish it off he glued small neodymium magnets to the top of the window frame which close the switches. It’s a very clean build and quite inexpensive to do — the possibilities for wiring up your entire home like this are quite tempting!
He’s got the switches installed already… why not couple it all to a complete home security setup? We shared a project last year that does just that!
This Tweeting cat door uses the Electric Imp to read a sensor and report back to the server. The hardware is pretty neat. The board hosts an ARM Cortex-M3 processor and gets on your home network via WiFi. The mini-USB cable simply provides the power. Programming is done over the network. Our own [Brian Benchoff] had a chance to try the Imp out earlier in the Fall.
Monitoring a cat door is as good a reason as any to undertake a project. The hardware added to the board includes a reed switch mounted on the jamb along with a magnet on the door itself. There is also a blue LED that gives a bit of user feedback. The software isn’t quite as easy but it still wasn’t that bad. As with most web-connected projects getting all the parts to talk to each other was a bit of a chore. The Imp reports back to a server on the local network which then activates a PHP script that uses Sen.se to push out a Tweet.