Cantennas outperform every consumer-grade Wi-Fi antenna I’ve had the bad luck of purchasing. Cantenna is a mashup of ‘can’ and ‘antenna’ creating the nickname for a directional waveguide antenna built from re-purposed steel cans. For anyone who has yet to build one, it makes an excellent afternoon project. Here are some build instructions and technical details. I went beyond that, and ended up catching a rogue WiFi access point in the process.
When I needed to extend the range of some ESP8266-based sensors, cantennas were right at the top of my list of things to try. It was easy enough to build one, attach it to a Wemos Mini D1 Pro, and call the job done… leaving me with plenty of time to over-engineer it, and I ended up down a bit of a rabbit hole.
The first thing I did was stop using cans. Canned goods are not only expensive in my corner of the world, but more importantly don’t lend themselves that well to making a standardized antenna in volume. I can also only eat so many beans! The latter reason alone is enough to consider an alternative design like a modular dish reflector.
Your grandmother means well. But by the time she figures out something’s a fad, it is old news. So maybe you got a fidget spinner in your stocking this year. Beats coal. Before you regift it to your niece, you could repurpose it to be a motor. Technically, [B.Aswinth Raj] made a brushless motor, although it isn’t going to fly your quadcopter anytime soon, it is still a nice demonstrator.
You can see a video below. The idea is to put magnets on the spinner and use an electromagnet to impart energy into the spinner which is on a piece of threaded rod left over from your last 3D printer build. A hall effect sensor determines when to energize the electromagnet.
A brushed motor uses a spring-loaded brush to carry current through to the motor’s coils and keep the magnetic field oriented properly. A brushless motor works differently. There are several schemes that will work, but the one [Raj] uses is the most common. He adds fixed magnets on the rotor then uses an electromagnet to provide the correct push at the right time. A practical brushless motor will likely have more than one coil, though, and the controller has to do a particular sequence to move the rotor around the rotation.
If you want to see the insides of a real motor, we looked at how to rewind them earlier. If you’d rather repurpose your spinner to something more practical, you could always make some music.
Whether or not you feel the need to laser cut custom drink coasters, you have to be impressed by the amount of thought that went into Coasty.
They say that justice is blind, and while we can’t promise you anything at your next court date, we can at least say with confidence that we’re not the kind of people who will turn down a good hack just because it’s held together with rubber bands and positive vibes. If it works it works, and it doesn’t matter what it looks like. Having said that, we’re blown away by how incredibly finished this particular project is.
Coasty, designed and built by [Bart Dring] is one of those projects that elevate a hack into something that looks like it could be a commercial product. It takes in a common pulpboard coaster and laser cuts any design you want. It’s just the right size, with just the right components because this is Coasty’s purpose. It has a slot to feed in the coaster, and uses this as one of the axes during the laser cutting process, with the laser’s left to right movement as the other. This method makes for a smaller overall footprint and means you never need to open the protective enclosure for normal operation.
Coaster cutting example from the video found below
Rear view. Note air filter and modular stepper drivers.
One of the most striking elements of Coasty is how much of the hardware is 3D printed. If it isn’t a motor, smooth rod, or other mechanical component, it’s printed. We’re used to seeing 3D printed parts as brackets or mounts, but rarely do you see an entire chassis printed like this. Not only does it take a serious amount of forethought and design, but the print time itself can be quite prohibitive.
But by designing and printing the majority of Coasty, it really gives it a professional look that would have been harder to achieve if it was a bundle of aluminum extrusions.
The back of Coasty features an exposed PCB “motherboard” with a dizzying array of plug-in boards. Hardware like the stepper drivers, Bluetooth radio, and laser power supply are separate modules for ease of maintenance and development. There’s a few neat hardware features integrated into the motherboard as well, like the IR sensor for detecting the edge of the coaster.
The printed filter is an especially nice touch. Containing a scrap of commercially available carbon cloth intended for home air filters, Coasty is able to cut down on the smoke that is invariably produced when blasting cardboard with a 3W 450nm laser.
