An Arduino-Free Automatic Alcohol Administrator

With all the hands-free dispenser designs cropping up out there, the maker world could potentially be headed for an Arduino shortage. We say that in jest, but it’s far too easy to use an Arduino to prototype a design and then just leave it there doing all the work, even if you know going in that it’s overkill.

[ASCAS] took up the challenge and built a cheap and simple dispenser that relies on recycled parts and essential electronics. It uses an IR proximity sensor module to detect dirty digits, and a small submersible pump to push isopropyl alcohol, sanitizer, or soap up to your hovering hand. The power comes from a sacrificial USB cable and is switched through a transistor, so it could be plugged into the wall or a portable power pack.

We admire the amount of reuse in this project, especially the nozzle-narrowing ballpoint pen piece. Be sure to check out the build video after the break.

Hopefully, you’re all still washing your hands for the prescribed 20 seconds. If you’re starting to slip, why not build a digital hourglass and watch the pixels disappear?

Continue reading “An Arduino-Free Automatic Alcohol Administrator”

Harry Potter Wand Hack Makes Magic Real

Any sufficiently advanced hack is indistinguishable from magic, a wise man once observed. That’s true with this cool build from [Jasmeet Singh] that magically opens a box when you wave a Harry Potter magic wand in the right way. Is it magic? No, it’s a neat hack that uses computer vision to track the wand and recognize when you make the magic gesture.

The trick is based on the same technique that Universal Studios use in their Harry Potter theme park, as detailed in a patent with the snappy title of “System and method for tracking a passive wand and actuating an effect based on a detected wand path“. The basic idea is that a retroreflective dot on the end of the wand reflects light from a set of infra-red LEDs around the camera. An infra-red sensitive camera detects this reflected light as a bright dot. This camera is tied into a computer vision system that tracks the path of the dot, then triggers the action if it follows a certain pattern.

The version that [Jasmeet] built uses a Raspberry Pi NoIR camera, and a Raspberry Pi 3 running OpenCV. This feeds into a machine learning graph that detects the letters of the alphabet. If the detected letter is an A (for Alomahora, the Harry Potter open spell), then the box opens. If it is a C, the box closes. This is all tied together using Python.

It’s a neat build that ties together a number of interesting techniques, and which could keep the kids amused for a while. You could also expand it further, such as adding a death ray that triggers if you trace an S for Sectumsempra. That’ll teach them not to mess with the dark arts.

Continue reading “Harry Potter Wand Hack Makes Magic Real”

Hackaday Links: April 5, 2020

Git is powerful, but with great power comes the ability to really bork things up. When you find yourself looking at an inscrutable error message after an ill-advised late-night commit, it can be a maximum pucker-factor moment, and keeping a clear enough head to fix the problem can be challenging. A little proactive social engineering may be in order, which is why Jonathan Bisson wrote git-undo, a simple shell script that displays the most common un-borking commands he’s likely to need. There are other ways to prompt yourself through Git emergencies, like Oh Shit, Git (or for the scatologically sensitive, Dangit Git), but git-undo has the advantage of working without an Internet connection.

Suddenly find yourself with a bunch of time on your hands and nothing to challenge your skills? Why not try to write a program in a single Tweet? The brainchild of Dominic Pajak, the BBC Micro Bot Twitter account accepts tweets and attempts to run them as BASIC programs on a BBC Microcomputer emulator, replying with the results of the program. It would seem that 280 characters would make it difficult to do anything interesting, but check out some of the results. Most are graphic displays, some animated, and with an unsurprising number of nods to 1980s pop culture. Some are truly impressive, though, like Conway’s Game of Life written by none other than Eben Upton.

The COVID-19 pandemic is causing all sorts of cultural shifts, but we didn’t expect to see much change in the culture of a community that’s been notoriously resistant to change for over a century: amateur radio. One of the most basic facts of life in the amateur radio world is that you need a license to participate, with governments regulating the process. But as a response to the pandemic, Spain has temporarily lifted licensing requirements for amateur radio operators. Normally, an unlicensed person is only allowed to operate on amateur bands under the direct supervision of a licensed amateur. The rules change allows unlicensed operators to use a station without supervision and is intended to give schoolchildren trapped at home an educational experience. In another change, some countries are allowing special callsign suffixes, like “STAYHOME,” to raise awareness during the pandemic. And the boom in interest in amateur radio since the pandemic started is remarkable; unfortunately, finding a way to take your test in a socially distant world is quite a trick. Our friend Josh Nass (KI6NAZ) has some thoughts about testing under these conditions that you might find interesting.

And finally, life goes on during all this societal disruption, and every new life deserves to be celebrated. And when Lauren Devinck made her appearance last month, her proud parents decided to send out unique birth announcement cards with a printed circuit board feature. The board is decorative, not functional, but adds a distinctive look to the card. The process of getting the boards printed was non-trivial; it turns out that free-form script won’t pass most design rule tests, and that panelizing them required making some compromises. We think the finished product is classy, but can’t help but think that a functional board would have really made a statement. Regardless, we welcome Lauren and congratulate her proud parents.

DIY Closed-Cell Silicone Foam

Most of us have a junk drawer, full of spare parts yanked from various places, but also likely stocked with materials we bought for a project but didn’t use completely. Half a gallon of wood glue, a pile of random, scattered resistors, or in [Ken]’s case, closed-cell silicone foam. Wanting to avoid this situation he set about trying to make his own silicone foam and had a great degree of success.

Commercial systems typically rely on a compressed gas of some sort to generate the foam. Ken also wanted to avoid this and kept his process simple by using basic (pun intended) chemistry to generate the bubbles. A mixture of vinegar and baking soda created the gas. After a healthy amount of trial and error using silicone caulk and some thinner to get the mixture correct, he was able to generate a small amount of silicone foam. While there only was a bit of foam, it was plenty for his needs. All without having a stockpile of extra foam or needing to buy any specialized equipment.

We appreciate this project for the ingenuity of taking something relatively simple (an acid-base reaction) and putting it to use in a way we’ve never seen before. While [Ken] doesn’t say directly on the project page what he uses the foam for, perhaps it or a similar type of foam could be used for building walk-along gliders.

Photo via Wikimedia Commons

Making An Arduino Ventilator? Read This First

Thanks to the virus crisis, lots of people are designing makeshift ventilator designs in the hopes of saving people’s lives. Many of these are based around some sort of Arduino-powered CPU. [Armstrong Subero] things that’s a great idea, but cautions that making an electronic pair of dice is a different proposition than creating a machine to breathe for someone. But he isn’t just complaining. He talks about considerations when building a real-time and safety-critical system.

[Armstrong] has a lot of good points, although we aren’t sure you need the complexity of a real-time operating system just to squeeze a bag. If anything, that seems like it might make it more susceptible to unexpected operation. However, we agree with his comments that you should have closed-loop control to make sure the device is working, alarming when the device isn’t working, and watchdog timers to guard against lockup.

Continue reading “Making An Arduino Ventilator? Read This First”

Data Glove Gets A Grip On Gesture Input

If we really want wearable computing to take off as a concept, we’re going to need lightweight input devices that can do some heavy lifting. Sure, split ergo keyboards are awesome. But it seems silly to restrict the possibilities of cyberdecks by limiting the horizons to imitations of desk-bound computing concepts.

What we really need are things like [Zach Freedman]’s somatic data glove. This fantastically futuristic finger reader is inspired by DnD spells that have a somatic component to them — a precise hand gesture that must be executed perfectly while the spell is spoken, lest it be miscast. The idea is to convert hand gestures to keyboard presses and mouse clicks using a Teensy that’s housed in the wrist-mounted box. You are of course not limited to computing on the go, but who could resist walking around the danger zone with this on their wrist?

Each finger segment contains a magnet, and there’s a Hall effect sensor in each base knuckle to detect when gesture movement has displaced a magnet. There’s a 9-DoF IMU mounted in the thumb that will eventually allow letters to be typed by drawing them in the air. All of the finger and thumb components are housed in 3D-printed enclosures that are mounted on a cool-looking half glove designed for weightlifters. [Zach] is still working on gesture training, but has full instructions for building the glove up on Instructables.

It’s true: we do love split ergo keyboarded cyberdecks, and this one is out of this world.

The CLUE Tracker Points You To A Target, Using CircuitPython

The main components are an Adafruit CLUE, Stemma GPS, and a lithium-polymer battery. No soldering required.

[Jay Doscher] shares a quick GPS project he designed and completed over a weekend. The device is called the CLUE Tracker and has simple goals: it shows a user their current location, but also provides a compass heading and distance to a target point. The idea is a little like geocaching, in that a user is pointed to a destination but must find their own way there. There’s a 3D printed enclosure, and as a bonus, there is no soldering required.

The CLUE Tracker uses the Adafruit CLUE board (which is the same size as the BBC micro:bit) and Stemma GPS sensor, with the only other active component being a lithium polymer battery. The software side of the CLUE Tracker uses CircuitPython, and [Jay] has the code and enclosure design available on GitHub.

[Jay] did a nice job of commenting and documenting the code, so this could make a great introductory CircuitPython project. No soldering is required, which makes it a little easier to re-use the parts in other projects later. This helps to offset costs for hackers on a budget.

The fact that a device like this can be an afternoon or weekend project is a testament to the fact that times have never been better for hobbyists when it comes to hardware. CircuitPython is also a fast-growing tool, and projects like this can help make it easy and fun to get started.