Misc Hacks

4086 Articles

Well-Built Sentry Gun Addresses The Menace Of Indoor Micro-UAVs

June 13, 2019 by 21 Comments

What is this world coming to when you can’t even enjoy sitting in your living room without some jamoke flying a drone in through the window? Is nothing sacred? Won’t someone think of the children?

Apparently [Drew Pilcher] did, and the result is this anti-drone sentry gun.  It’s a sturdily built machine – one might even say it’s overbuilt. The gimbal is made from machined steel pieces, and the swivels are a pair of Sherline stepper-controlled rotary tables with 1/40 of a degree accuracy selling for $400 each. Riding atop that is a Nerf rifle, which is cocked by a stepper-actuated linear slide, as well as a Kinect for object tracking. The tracking app is a little rough – just OpenCV hacked onto the Kinect SDK – but good enough for testing. The gun tracks as smoothly as one would expect given the expensive hardware, and the auto-cocking feature works well if a bit slowly. Based as it is on Nerf technology, this sentry is only indicated for the control of the micro-drones seen in the snuff video below, but really, anyone afflicted by indoor infestations of Phantoms or Mavics has bigger problems to worry about.

Over-engineered? Perhaps, but it’s better than letting the menace of indoor drones go unanswered. And it’s far from the first sentry gun we’ve seen, targeting everything from cats to squirrels using lasers, paintballs, and even plain water.

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An Exhaustive Guide To Building 18650 Packs

June 12, 2019 by 23 Comments

Most of us know the basics of building packs of lithium-ion batteries. We’re familiar with cell balancing and the need for protection circuitry, and we understand the intricacies of the various serial and parallel configurations. It’s still a process that can be daunting for the first-time pack-builder though, because the other thing that most of us know about lithium ion batteries is that getting things wrong can cause fires. Rule zero of hackerspaces is “Don’t be on fire”, so what’s to be done? Fortunately [Adam Bender] is on hand with an extremely comprehensive two-part guide to designing and building lithium-ion battery packs from cylindrical 18650 cells.

In one sense we think the two-parter is in the wrong order. Part two takes us through all the technical details and theory, from lithium-ion chemistry to battery management systems and spot-welding nickel busbars, while part one shows us the construction of his battery pack. There are also a couple of videos, which we’ve placed below the break. It’s still not a job for the faint-hearted, but we’d say he’s produced about as professional and safe a pack as possible.

If spot welding worries you then it might be possible to build a pack without it. But it’s always worth considering: would you be better served buying one?

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Captivating ESP32 Camera Hack

June 10, 2019 by 16 Comments

You can never have enough DIY devices at home, so when you look at an ESP32 module that comes with the camera, you automatically start getting ideas. [Daniel Padilla] wanted a way to deploy DIY camera modules without the hassle of configuring them so he made one that looks like an access point and starts streaming as soon as you connect to it.[GitHub]

The code he provides allows the ESP32 to appear as an Open Access Point which you can connect to from a PC or smartphone. The awesome sauce here is that the ESP32 resolves all DNS requests to a redirect in a similar manner to what happens when someone connects to an open Wi-Fi access point in a mall, Instead of a captive portal page that asks the user to authenticate or accept terms and conditions, [Daniel Padilla]’s code instead redirects to the streaming page et voila! Instant camera stream, and it is that simple.

We love this project because it is an elegant way to solve a problem, and it also teaches newbies about captive portals and their implementation. We covered a cheap ESP32 Webcam in the past and this project also comes with code for you to get started. We would love to see what you come up with next.

Homebrew Laptop Makes A Statement With A Steampunk Theme

June 9, 2019 by 15 Comments

Some may argue, but your choice of computing hardware says exactly zero about you, at least when you buy off the shelf. Your laptop or PC is only one of millions, and the chances of seeing someone with the exact same machine are pretty good. If you want to be different, you really need to build something yourself.

This homebrew steampunk laptop does a great job at standing out from the crowd. [Starhawk]’s build is an homage to the Steampunk genre, in a wooden case with brass bits and bobs adorning. The guts are based on an Intel motherboard, a bit dated but serviceable enough for the job. There’s a touch-capable LCD in the lid, and we absolutely love the look of the keyboard with its retro-style chrome and phenolic keycaps. Exposed USB cables run to and fro, and the braided jackets contribute to the old-timey look. The copier roller as a lid hinge is a nice touch too.

[Starhawk]’s build log is long and detailed, and covers the entire build. We’ve seen interesting builds from him before, like this junk-bin PC build for a friend in need. Looks like this one is for personal use, though, and we can’t blame him.

Simulated Newton’s Cradle Makes A Flashy Desk Toy

June 1, 2019 by No comments

Newton’s Cradle was once upon a time, a popular desk toy in offices around the world. For [TecnoProfesor], however, it wasn’t quite flashy enough. Instead, they built a simulated version with flashing LEDs. As you do.

Rather than relying on the basic principles of the cradle to make it work, this relies on two servo motors to move the balls on the ends, with the ones in the middle remaining stationary. Each ball is fitted with an RGB LED, which flashes with the simulated “motion” of the cradle. By using ping pong balls, the light from the LEDs is nicely diffused. The frame is built from wooden dowels, metal rods, and acrylic.

It’s a project that is sure to confuse at first glance, but it’s a great way to learn basic microcontroller skills like interfacing with LEDs and servomotors. We’d love to see a version that works like a real Newton’s Cradle, flashing the LEDs as they are hit by their neighbours. We’ve even seen them automated, for the truly lazy among us.  Alternatively, one could go completely ridiculous and have such a device tweet on every hit, though you might run afoul of the API’s spam restrictions. If you give it a go, drop us a line.

Ferrofluid Display Fuels The Fun, And The Procrastination

May 28, 2019 by 14 Comments

When deadlines loom and your future is on the line, do what top college students through the ages have always done: procrastinate! [Simen] and [Amund] did that in grand style by starting a YouTube channel, delightfully and aptly named “Applied Procrastination”, wherein they plan to avoid their responsibilities as long as possible in favor of making a large-scale ferrofluidic display panel. (Video, embedded below.)

We suppose we should encourage them to hit the books, but honestly they look like they’re having much more fun and learning more than they would in class. The idea isn’t new; we’ve seen ferrofluid clocks before, after all. [Amund] and [Simen] have grander plans for their display, but they’re wisely starting small with basic experiments. They had an early great idea to use a double-pane window as a tank for their display, but coatings on the inside of the glass and the aluminum frame conspired to cloud the display. They also did some tests to make sure they can control 252 electromagnets safely. They did manage to get a small test display working, but really the bulk of the video is just them playing with magnets and ferrofluid. And again, we’re OK with that.

It looks like this is going to be an interesting project, with hopefully regular updates to the channel now that summer break is upon us. Unless they find something else to do, of course.

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For Better Photogrammetry, Just Add A Donut

May 14, 2019 by 19 Comments

If you don’t have access to a 3D scanner, you can get a lot done with photogrammetry. Basically, you take a bunch of pictures of an object from different angles, and then stitch them together with software to create a 3D model. For best results, you need consistent, diffuse lighting, an unchanging background, and a steady camera.

Industrial designer [Eric Strebel] recently made an Intro to Photogrammetry video wherein he circled an object taking photos with his bare hands. One commenter suggested a different method: build a donut-shaped turntable that circles the object, which sits on a stationary platform. Attach the camera to the donut, counterbalance the weight, and Bob’s your proverbial uncle. [Eric] thought it was a brilliant idea (because it is), and he built a proof of concept. This is that video.

[Eric] can move the camera up and down the arc of the boom to get all the Z-positions he wants. The platform has a mark every 10° and there’s a pointer in the platform to line them up against for consistent camera positioning. He was pleasantly surprised by the results, which we agree are outstanding.

We always learn a lot from [Eric]’s videos, and this one’s no exception. Case in point: he makes a cardboard mock-up by laying out the pieces, and uses that to make a pattern for the recycled plywood and melamine version. In the photogrammetry video, he covers spray paint techniques to make objects reflect as little light as possible so the details don’t get lost.

If you prefer to rotate your objects, get an Arduino out and automate the spin.

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