misc hacks

Pulleys within Pulleys form a Unique Transmission for Robots

September 25, 2017 by 4 Comments

After a couple of millennia of fiddling with gears, you’d think there wouldn’t be much new ground to explore in the field of power transmission. And then you see something like an infinitely variable transmission built from nested pulleys, and you realize there’s always room for improvement.

The electric motors generally used in robotics can be extremely efficient, often topping 90% efficiency at high speed and low torque. Slap on a traditional fixed-ratio gearbox, or change the input speed, and efficiency is lost. An infinitely variable transmission, like [Alexander Kernbaum]’s cleverly named Inception Drive, allows the motor to stay at peak efficiency while smoothly changing the gear ratio through a wide range.

The mechanism takes a bit of thought to fully grok, but it basically uses a pair of split pulleys with variable spacing. The input shaft rotates the inner pulley eccentrically, which effectively “walks” a wide V-belt around a fixed outer pulley. This drives the inner pulley at a ratio depending on the spacing of the pulley halves; the transmission can shift smoothly from forward to reverse and even keep itself in neutral. The video below will help you get your head around it.

We’ve seen a couple of innovative transmissions around here lately; some, like this strain-wave gear and this planetary gearbox, are amenable to 3D printing. Looks like the Inception Drive could be printed too. Hackers, start your printers and see what this drive can do.

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Fun-Size Geiger Counter Sits atop a 9-Volt Battery

September 20, 2017 by 29 Comments

Want a little heads-up before walking into a potentially dangerous radioactive area? Sure, we all do. But the typical surplus Civil Defense Geiger counter is just too bulky to fit into the sleek, modern every-day carry of the smartphone age. So why not slim down your first line of defense against achieving mutant status with this tiny Geiger counter (Facebook)?

We jest about the use cases for a personal-sized Geiger counter, as [Ian King]’s inspiration for this miniaturized build was based more on a fascination with quantifying the unseen world around us. Details are thin in his post, but [Ian] kindly shared the backstory for this build with us. Working on a budget and mostly with spare parts, the big outlay in the BOM was $20 for a Soviet-era SBM-10 tube, itself a marvel of miniaturization. While waiting the two months needed for the tube to arrive, [Ian] whipped up a perf board circuit with a simple oscillator and a CFL transformer to provide the 400 volts needed for the tube. The whole circuit, complete with tiny speaker and an LED to indicate pulses, sits neatly on top of a 9-volt battery. The video below shows it in action with a test source.

Geiger counters are not exactly rare projects on Hackaday, and with good reason. Take a look at this no-solder scrap bin counter or this traveling GPS Geiger counter built dead-bug style.

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Chest of Drawers Stores Audio Memories

September 18, 2017 by 15 Comments

Some people collect stamps, some collect barbed wire, and some people even collect little bits of silicon and plastic. But the charmingly named [videoschmideo] collects memories, mostly of his travels around the world with his wife. Trinkets and treasures are easy to keep track of, but he found that storing the audio clips he collects a bit more challenging. Until he built this audio memory chest, that is.

Granted, you might not be a collector of something as intangible as audio files, and even if you are, it seems like Google Drive or Dropbox might be the more sensible place to store them. But the sensible way isn’t always the best way, and we really like this idea. Starting with what looks like an old card catalog file — hands up if you’ve ever greedily eyed a defunct card catalog in a library and wondered if it would fit in your shop for parts storage — [videoschmideo] outfitted 16 drawers with sensors to detect when they’re opened. Two of the drawers were replaced by speaker grilles, and an SD card stores all the audio files. When a drawer is opened, a random clip from that memory is played while you look through the seashells, postcards, and what-have-yous. Extra points for using an old-school typewriter for the drawer labels, and for using old card catalog cards for the playlists.

This is a simple idea, but a powerful one, and we really like the execution here. This one manages to simultaneously put us in the mood for some world travel and a trip to a real library.

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Building a Working Game of Tetris in Conway’s Game of Life

September 17, 2017 by 21 Comments

If you haven’t been following along with Conway’s Game of Life, it’s come a long way from the mathematical puzzle published in Scientific American in 1970. Over the years, mathematicians have discovered a wide array of constructs that operate within Life’s rules, including many that can be leveraged to perform programming functions — logic gates, latches, multiplexers, and so on. Some of these creations have gotten rather huge and complicated, at least in terms of Life cells. For instance, the OTCA metapixel is comprised of 64,691 cells and has the ability to mimic any cellular automata found in Life.

A group of hackers has used OTCA metapixels to create a Tetris game out of Life elements. The game features all 7 shapes as well as the the movement, rotation, and drops one would expect. You can even preview the next piece. The game is the creation of many people who worked on individual parts of the larger program. They built a RISC computer out of Game of Life elements, as well as am assembler and compiler for it, with the OTCA metapixels doing the heavy lifting. (The image at the top of the post is the program’s data synchronizer.

Check out the project’s source code on GitHub, and use this interpreter. Set the RAM to 3-32 and hit run.

For a couple of other examples of Life creations, check out the Game of Life clock and music synthesized from Life automata we published earlier.

A Fix for the Lightweight Machine Tool Shakes

September 16, 2017 by 12 Comments

No matter what material you work with, the general rule is that with machine tools, the heavier, the better. Some people can’t afford or don’t want big tools, though, even with their natural tendency to reduce vibrations. That doesn’t mean something can’t be done to help the little tools, like reducing vibration in a contractor-grade table saw.

This one might seem a little outside the usual confines of the hackosphere, but nobody can doubt [Matthias Wandel]’s hacker chops and he really shows off his problem-solving skills with this one. His well-worn contractor-style table saw has had more than a few special modifications over the years, some of which left it with a shimmy sufficient to vibrate workpieces right off the table. He fashioned a friction damper for the saw’s motor from wood, complete with ball and socket joints to allow full movement of the blade height and angle. That didn’t quite do the trick, but his incremental approach finally found the right combination of factors, and the video below shows a saw now stable enough to balance a nickel.

If the name seems familiar but you just can’t place the hacks, check out [Matthias]’s recent wooden domino extruder, his shortcuts to tapping wood, or of course his classic wood gears layout software.

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Hacker Maketh Kingsman Umbrella

September 15, 2017 by 11 Comments

Yes! Someone made the Kingman umbrella and yes it can shoot and yes it has a display on the inside. [James Hobson] just put up a video on YouTube for this excellent project detailing the process that went into creating this live working prop and it is amazing.

The build starts with finding a rugged umbrella and was tested by standing on it as well as decimating a few household objects. Compress CO2 cartridges provide the fuel for propelling blow darts as well as other non-lethal forms of ammunition. The coolest part of the project is the screen inside the portable that allows you to see-through the dome. This is accomplished by a combination of a small camera and a portable mini projector. Simple yet awesome.

The camera is mounted near the muzzle whereas the projector is sliced-up and integrated into the grip. The handle in question is itself 3D printed and includes a custom trigger into the design. Check out the video for a demonstration of the project.

Movie props have a special place in every maker’s heart and this project is an excellent example of imagination meeting ingenuity. After seeing this video, security agencies are going to be giving umbrella owners some suspicious looks though creating own of your own could be a very rewarding experience. If you are looking for a more obvious prop, then check out the PiPBoy Terminal from Fallout which is sure to get everyone’s attention. Continue reading “Hacker Maketh Kingsman Umbrella” →

Tesla Coil uses Vintage Tube

September 14, 2017 by 4 Comments

We’ve seen a fair amount of Tesla coil builds, but ones using vacuum tubes are few and far between. Maybe it’s the lack of availability of high power tubes, or a lack of experience working with them among the younger crop of hackers. [Radu Motisan] built a vacuum tube Tesla coil several years back, and only just managed to tip us off recently. Considering it was his first rodeo with vacuum tubes, he seems to have done pretty well — not only did he get good results, he also managed to learn a lot in the process.

His design is based around a GI-30 medium power dual tetrode. The circuit is a classical Armstrong oscillator with very few parts and ought to be easy to build if you can lay your hands on the tricky parts. The high voltage capacitors may need some scrounging. And of course, one needs to hand-wind the three coils that make up the output transformer.

Getting the turns ratios of the coils right is quite critical in obtaining proper power transfer to the output. This required a fair amount of trial error before [Radu] could get it right.

The use of a 20W fluorescent tubelight ballast to limit the inrush current is a pretty nice idea to prevent nuisance tripping of the breakers. If you’d like to try making one of your own, head over to his blog post where you will find pictures documenting his build in detail. If you do decide to make one, be extremely careful — this circuit has lethal high voltages in addition to the obvious ones, since it operates directly from 220 V utility supply.

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