On paper, pet doors are pretty great. You don’t have to keep letting the cat in and out, and there should be fewer scratches on the door overall. Unfortunately, your average pet door is indiscriminate, and will let any old creature waltz right in. Well, [Jeremiah] was tired of uninvited critters, so he built a motorized door with a built-in bouncer. Now, only animals with pre-approved BLE tags can get in.
The bouncer is a Raspi 3 running Node-RED, which scans continuously for BLE advertisements from the cats’ collars. [Jeremiah] settled on Tile tags because they’re reliable and cat-proof. The first version used an Arduino and RFID tags for the cats, but they had to get too close to the door to trigger it.
We love [Jeremiah]’s choice of door actuator, a 12V retractable car antenna. [Jeremiah] uses the antenna itself to lift and lower the removable lockout panel that comes with the door. He removed the circuit that retracts the antenna when power is lost, so that power outages don’t become free-for-alls for shelter-seeking animals.
There’s also a nice feature for slow creatures—the door won’t close until 15 seconds after the last BLE ad, so they cats won’t ever have to Indiana Jones it through the opening. Magnetic switches currently limit the door travel at the top and bottom, though [Jeremiah] will eventually replace them with standard switches. Paw at the break until you get a walk-through video.
As difficult as it might be to believe, the tiles you’re seeing here weren’t made on some exotic ceramic printer, but a standard Prusa i3 MK3. Well, at least they started on the 3D printer. As you might have guessed, there’s a bit more involved than that.
That said, the idea is actually quite simple. The printed “tile” is just the base plate, plus the raised elements that will eventually be seen on the surface. Everything else is just a void, which naturally saves a lot on printing time and material. Once the print is done, premixed spackling paste is pushed into all of the open areas and the top is made as smooth as possible with a putty knife. The filled tile is then left to dry for 24 hours or so.
Once it’s dried, you take the tile outside and sand the top down with a palm sander (or by hand, if you have the patience). This not only smooths out the spackle, but eventually will expose and then smooth the top parts of the print. Once everything is nice and silky, it gets sprayed with a semi-gloss clear coat to both protect it and give it that authentic looking shine.
[Matthew] actually created his designs based on images of real Azulejo tiles he found online, but really any sort of image that has raised elements like this could be made to work. If anyone out there decorates their home with 3D printed Jolly Wrencher tiles, you know where to send the pictures. Interestingly, these aren’t the first tiles we’ve seen made out of plastic, but we’ve got to admit these ones would look quite a bit more appealing on your kitchen walls.
A Tile is a small Bluetooth device which you can put on your keychain, for example, so that you can find your keys using an app on your phone. Each Tile’s battery life expectancy is one year and after that year you’re expected to trade it in at a discount for a new one. Right away your hacker senses are tingling and you know what’s coming.
[Luis Rodriguez] had switched to Samsung SmartThings and had accumulated box of these Tiles with dead batteries. So he decided a fun project would be to put a Tile in his wife’s car to track it. Given that it’s using Bluetooth, the range isn’t great for car tracking, but the Tile’s app can network with other user’s apps to widen the search area.
Since the Tile’s battery was dead, he cracked it open and soldered wires to its power terminals. He then found a handy 12 volt source in the car and added a DC to DC buck converter to step the voltage down to the Tile’s 3 volts. Finding a home for the hacked tracker was no problem for [Luis]. He was already using an ODB-II dongle for a dash cam so he tapped into the 12 V rail on that.
You’ll be surprised what you can find by hacking these small tracking devices. Here’s an example of hacking of a fitness tracker with all sorts of goodies inside.
Our thanks to [Maave] for tipping us off about this hack.
Recycling aims to better the planet, but — taken into the hands of the individual — it can be a boon for one’s home by trading trash for building materials. [fokkejongerden], a student at the [Delft University of Technology] in the Netherlands, proposes one solution for all the plastic that passes through one’s dwelling by turning HDPE into tiles.
Collecting several HDPE containers — widely used and easy enough to process at home — [fokkejongerden] cleaned them thoroughly of their previous contents, and then mulched them with a food processor. An aluminium mold of the tile was then welded together making sure the sides were taller than the height of the tile. A second part was fabricated as a top piece to compress the tile into shape.
After preheating an oven to no hotter than 200 degrees Celsius, they lined the mold with parchment paper and baked the tile until shiny(90-120 minutes). The top piece was weighed down (clamping works too), compressing the tile until it cooled. A heat gun or a clothes iron did the trick to smooth out any rough edges.
Not only does [fokkejongerden]’s tiles give the recycler plenty of artistic freedom for creating their own mosaic floor, the real gem is the adaptable plastic recycling process for home use. For another method, check out this recycled, recycling factory that turns bottles in to rope and more! There’s even the potential for fueling your 3D printer.
The Tile is a small Bluetooth chip, speaker, and enough battery for a year in a keychain format. If you lose your keys in the morning, simply use the app on your phone to find the keychain. If you lose your phone simply get out your second phone.
This planned obsolescence didn’t jive with [JM] when his Tile stopped being discoverable. He didn’t want to toss a gadget that had served him so well into the landfill. So, like any good hacker, he cracked its plastic case open.
The Tile itself is a really interesting product. The largest component is the battery which has tabs spot-welded to its surface. Attached to those is a well laid out board. [JM] points out the clever use of spring contacts to engage the piezo element for the speaker as a nice example of good design for manufacture.
The hack itself was pretty easy to complete. Some electrical tape and soldering was all it took to embed the tile into the remote. Now he can take out his phone and press a button to hear a forlorn beep coming from under the couch cushions.
Chest freezers are perfect for these builds as their top door design helps keep the cold air inside to boost the efficiency. The trick is to modify them without messing up the insulating properties of the appliance housing. [GMMN’s] approach is a common one, build a cuff to go in between the lid and the body of the freezer. He started by building a wooden box open at both the top and the bottom. Many would have stopped there but to bring the bling he tiled the sides and front of that cuff, leaving an empty spot for the shank of each tap. With that taken care of he glued insulation to the inside of the cuff, and added weather-stripping to the bottom to seal with the top of the case. He used the holes from the lid hinge brackets to attach his add-on so that the freeze can be converted back to stock without any sign of his alterations.
We’ve seen our fair share of AVR projects, but this one’s pretty cool. AVGA is a color video game development platform based on the Atmel AVR family of microcontrollers. As seen in the picture above, one of the AVRs that the project uses is the popular ATMega168. There were several technical hurdles to using the AVRs to run color video games; one of the most difficult problems was figuring out a way to display detailed graphics from AVRs limited onboard RAM. Eventually, the developers figured out a way to display detailed graphics using a TILE-based driver. The TILE driver works by dividing the screen into X and Y coordinates, dividing the graphics into tiles. Then, when a graphic is needed it’s addressed from a reference table that’s stored in the AVR’s onboard RAM, allowing the bitmap graphic to be loaded from a game’s ROM. Currently, the only games available for the platform are a Super Mario clone, a Pacman clone, and a Snake clone. While there are only a few games available, the platform definitely looks promising. If anything, this project serves as a great example for what off the shelf microcontrollers are capable of.