Assemble Your Own Modular Li-Ion Batteries

Low-voltage DC power electronics are an exciting field right now. Easy access to 18650 battery cells and an abundance of used Li-Ion cells from laptops, phones, etc. has opened the door for hackers building their own battery packs from these cheap cells. A big issue has been the actual construction of a pack that can handle your individual power needs. If you’re just assembling a pack to drive a small LED, you can probably get by with spring contacts. When you need to power an e-bike or other high power application, you need a different solution. A spot welder that costs $1000 is probably the best tool, but out of most hackers’ budget. A better solution is needed.

Vruzend v2 Battery Caps.

Enter [Micah Toll] and his Vruzend battery connectors, whose Kickstarter campaign has exceded its goal several times over. These connectors snap onto the ends of standard 18650 cells, and slot together to form a custom-sized battery pack. Threaded rods extend from each plastic cap to enable connection to a bus bar with just a single nut. The way that you connect each 18650 cell determines the battery pack’s voltage and current capability. There are a couple of versions of the connector available through the campaign, and the latest version 2.0 should allow some tremendously powerful battery pack designs. The key upgrade is that it now features corrosion-resistant, high-power nickel-plated copper busbars allowing current up to 20A continuous. A side benefit of these caps instead of welded tabs is that you can easily swap out battery cells if one fails or degrades over time. Continue reading “Assemble Your Own Modular Li-Ion Batteries”

Cable Bots, Arise! Domination of the Universe is at Hand

Most CNC robots people see involve belts and rails, gantries, lead screws, linear bearings, and so forth. Those components need a rigid chassis to support them and to keep them from wobbling during fabrication and adding imperfections to the design. As a result, the scale is necessarily small — hobbyist bots max out at cabinet-sized, for the most part. Their rigid axes are often laid out at Cartesian right angles.

One of the exceptions to this common configuration is the delta robot. Deltas might be the flashiest of CNC robots, moving the end effector on three arms that move to position it anywhere in the build envelope. A lot of these robots are super fast and precise when charged with carrying a light load, and they get put to work as pick-and-place machines and that sort of thing. It doesn’t hurt that delta bots are also parallel manipulators, which means that the motors work together to move the end effector, with one motor pulling while the matching motor pulls.

But while Cartesian CNC bots are sturdy workhorses, and deltas are fly-weight racehorces, neither can really cut it when you want to go gigantic. In terms of simplicity and scale, nothing beats cable bots.

Cable Bots

Cable bots use wires or strings pulled by reel-mounted motors, with dimensions limited only by the room to mount the motors and the tensile strength of the cables used. When the strings are tensioned you can get a surprising degree of accuracy. Why not? Are they not computer-controlled motors? As long as your kinematic chain accounts for the end effector’s movement in one direction by unwinding another cable (for instance) you can very accurately control the end effector over a very wide scale.

The following are some fun cable bots that have caught my eye.

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Winch Bot Records Hacks and Cats

Some people are better than others when it comes to documenting their hacks. Some people, like [Micah Elizabeth Scott], aka [scanlime], set the gold standard with their recordings. Hacking sessions with the Winch Bot have been streamed regularly throughout the build and this is going to lead to a stacking effect in her next projects because the Winch Bot was designed to record hacking sessions. Hacking video inception anyone? Her Winch Bot summary video is after the break.

The first part of this build, which she calls the Tuco Flyer, was [Micah Elizabeth Scott]’s camera gimbal hack which we already covered and is a wonderful learning experience in itself. She refers to the gimbal portion as the “flyer” since it can move around. The Winch Bot contains the stationary parts of the Tuco Flyer and control where the camera will be in the room.

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Print A Flexible Keypad

[Micah Elizabeth Scott] needed a custom USB keyboard that wrapped around a post. She couldn’t find exactly what she wanted so she designed and printed it using flexible Nijaflex filament. You can see the design process and the result in the video below.

The electronics rely on a Teensy, which can emulate a USB keyboard easily. The keys themselves use the old resistor divider trick to allow one analog input on the Teensy to read multiple buttons. This was handy, but also minimized the wiring on the flexible PCB.

The board itself used Pyralux that was milled instead of etched. Most of the PCB artwork was done in KiCAD, other than the outline which was done in a more conventional CAD program.

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Bibles You Should Read: PoC || GTFO

PASTOR LAPHROAIG ANNOUNCES THE PUBLICATION OF WHAT WILL TORMENT THE ACOLYTES OF THE CHURCH OF ROBOTRON! NO MAN SHALL BE SPARED AND THE INQUISITION WILL BEGIN PROMPTLY!

For the last few years, Pastor Manul Laphroaig and friends have been publishing the International Journal of PoC || GTFO. This is a collection of papers and exploits, submitted to the Tract Association of PoC || GTFO, each of which demonstrates an interesting exploit, technique, or software toy in the field of electronics. Imagine, if 2600 or Dr. Dobb’s Journal were a professional academic publication. Add some whiskey and you have PoC || GTFO.

This is something we’ve been waiting a while for. The International Journal of PoC || GTFO is now a real book bible published by No Starch Press. What’s the buy-in for this indulgence? $30 USD, or a bit less if you just want the Ebook version. The draw of the dead tree version of PoC includes a leatherette cover, gilt edges, and the ability to fit inside bible covers available through other fine retailers. There are no rumors of a children’s version with vegetable-based characters.

PoC || GTFO, in reality, is an almost tri-annual journal of reverse engineering, computer science, and other random electronic computational wizardry, with papers (the Proof of Concept) by Dan Kaminsky, Colin O’Flynn, Joe FitzPatrick, Micah Elisabeth Scott, Joe Grand, and other heroes of the hacker world. What does PoC || GTFO present itself as? Applied electrons in a religious tract publication. The tongue is planted firmly in the cheek here, and it’s awesome.

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The Internet Of Interactive Cats

[Tuco] is a cat who shares the space of [Micah Elizabeth Scott]. He is a large tabby tomcat, and he is polydactyl, which is to say he has a congenital excess of toes. He is an extremely active and engaging creature and enjoys playing and interacting with her. We covet [Tuco].

Sadly for the rest of us who love cats, of course, unless we know [Micah] personally we’ll never have the opportunity to play with [Tuco]. She appreciates the cat-shaped void that will leave in our lives, and to help us she’s building a telepresence robot to allow the rest of us to interact with him in real time.

Her idea is to make a flying robot equipped with a camera on a gimbal, and because to mounting it on a multirotor platform would be a hazard, instead she’s making something closer to the aerial cameras you might be familiar with from sporting fixtures, a motorised platform suspended from the corners of her roof space on a set of nylon ropes, that can move at will by adjusting the length of each tether. It is suggested that one day the device will be able to launch plastic bolts for [Tuco] to chase and to incorporate other interactive features to allow online users to engage with him.

We are shown progress so far in the video introducing the project that we’ve placed below the break, she has completed a prototype windlass mechanism and worked on reverse engineering the gimbal mechanism for serial control. We’ll probably never meet [Tuco] in person, but we can’t wait to interact with him online.

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Gimbal SDI Camera Mod

Sometimes when you need something, there is a cheap and easily obtainable product that almost fits the bill. Keyword: almost. [Micah Elizabeth Scott], also known as [scanlime], is creating a hovering camera to follow her cat around, and her Feiyu Mini3D 3-axis brushless gimbal almost did everything she’d need. After a few modifications, [Micah] now has a small and inexpensive 3-axis gimbal with a Crazyfire HZ-100P SDI camera and LIDAR-Lite distance sensor.

At thirty minutes long, [Micah’s] documenting video is rife with learning moments. We’ve said it before, and we’ll say it again: “just watch it and thank us later.” [Micah Elizabeth Scott] has a way of taking complicated concepts and processes and explaining things in a way that just makes sense (case in point: side-channel glitching) . And, while this hack isn’t exactly the most abstractly challenging, [Micah’s] natural talent as a teacher still comes through. She takes you through what goes right and what goes wrong, making sure to explain why things are wrong, and how she develops a solution.

Throughout her video, [Micah] shares small bits of wisdom gained from first-hand experience. From black hot glue to t-glase (a 3D printing filament), we learned of a few materials that could be mighty useful.

We’re no strangers to the work of [Micah Elizabeth Scott], she’s been on the scene for a while now. She’s been a Hackaday Prize Judge in 2015 and 2016 and is always making things we love to cover. She’s one of our three favorite hackers and has a beautiful website that showcases her past work.

Video after the break.

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