Should I Use Wheels Or Tracks?

February 26, 2021 by 32 Comments

When it comes to dominating offroad performance, many people’s first thought is of tracked vehicles. Bulldozers, tanks and excavators all use treads, and manage to get around in difficult terrain without breaking a sweat. Today, we’re exploring just what makes tracked vehicles so capable, as well as their weaknesses.

It’s All About Ground Pressure

The various parts of a tank’s propulsion system.

Let’s first look at how tank tracks work. There are a huge variety of designs, with differences depending on application. Different trends have been followed over time, and designs for military use in combat differ from those used for low-speed construction machines, for example. But by looking at a basic tank track design, we can understand the basic theory. On tanks, the track or tread itself is usually made up of individual steel links that are connected together with hinges, though other machines may use rubber tracks instead. The tracks are wrapped around one or more drive wheels, often cogged, which directly pull on the track. On the bottom of the vehicle are the road wheels, which ride on top of the track where it lies on the ground.  The weight of the vehicle is carried through the road wheels and passed on to the tread, spreading out the load across a broader area. Outside of this, the track system may also have one or more idler wheels used to keep the track taught, as well as return rollers to guide the track back around without touching the road wheels.

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DIY All-Transistor Addressable Pixel

February 26, 2021 by 36 Comments

By now most readers should be used to addressable LEDs, devices that when strung out in a connected chain can be individually lit or extinguished by a serial data stream. Should you peer at one under a microscope you’ll see alongside the LED dies an integrated circuit that handles all the address decoding. It’s likely to be quite a complex device, but how simply can its functions be replicated? It’s a theme [Tim] has explored in the TransistorPixel, and addressable LED board that achieves addressability with only 17 transistors.

It uses a surprisingly straightforward protocol, in which a pulse longer than 500ns enables the LED while a shorter one turns it off. Subsequent pulses in a train are passed on down the line to the next device. A 20µs absence of a pulse resets the string and sets it to wait for the next pulse train. Unlike the commercial addressable LEDS there is only a single colour and no suport for gradated brightness, but it’s still an impressive circuit.

Under the hood is some very old-school RTL logic, a monostable to detect the pulse and a selection of gates and a latch to capture the state and forward to the chain. It’s laid out on a PCB in order of circuit function, and while we can see that maybe it’s not a practical addresssable LED for 2021, it’s likely that it could be made into a much smaller PCB if desired.

Perhaps unsurprisingly given the ready availability of addressable LEDs, we’ve not seen many home made ones. This addressable 7-segment display may be the closest.

Homebrew Metrology The CERN Way

February 26, 2021 by 18 Comments

We won’t pretend to fully grok everything going on with this open-source 8.5-digit voltmeter that [Marco Reps] built. After all, the design came from the wizards at CERN, the European Organization for Nuclear Research, home to the Large Hadron Collider and other implements of Big Science. But we will admit to finding the level of this build quality absolutely gobsmacking, and totally worth watching the video for.

As [Marco] relates, an upcoming experiment at CERN will demand a large number of precision voltmeters, the expense of which led to a homebrew design that was released on the Open Hardware Repository. “Homebrew” perhaps undersells the build a bit, though. The design calls for a consistent thermal environment for the ADC, so there’s a mezzanine level on the board with an intricately designed Peltier thermal control system, including a custom-machined heat spreader blocker. There’s also a fascinatingly complex PCB dedicated solely to provide a solid ground between the analog input connector — itself a work of electromechanical art — and the chassis ground.

The real gem of this whole build, though, is the vapor-phase reflow soldering technique [Marco] used. Rather than a more-typical infrared process, vapor-phase reflow uses a perfluropolyether (PFPE) solution with a well-defined boiling point. PCBs suspended above a bath of heated PFPE get bathed in inert vapors at a specific temperature. [Marco]’s somewhat janky setup worked almost perfectly — just a few tombstones and bridges to fix. It’s a great technique to keep in mind for that special build.

The last [Marco Reps] video we featured was a teardown of a powerful fiber laser. It’s good to see a metrology build like this one, though, and we have a feeling we’ll be going over the details for a long time.

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Tired Of Popcorn? Roast Coffee Instead

February 25, 2021 by 17 Comments

We’ve seen a lot of coffee roaster builds over the years. [Ben Eagan] started his with a hot-air popcorn maker. If you think it is as simple as putting beans in place of the popcorn, think again. You need to have good control of the heat, and that requires some temperature monitoring and a controller — in this case, an Arduino. [Ben’s] video below shows how it all goes together.

With the Arduino and the power supply strapped to the sides, it looks a bit like something out of a bad post-apocalypse movie. But it looks like it gets the job done.

In addition to the Arduino, a thermocouple measures the temperature and that takes a little circuitry in the form of a MAX31855. There’s also a relay to turn the heater on and off. There are other ways to control AC power, of course, and if a relay offends your sensibilities you can always opt for a solid state one.

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Oddball X86 Instructions

February 25, 2021 by 66 Comments

David Letterman made the top ten list famous. [Creel] has a top ten that should appeal to many Hackaday readers: the top 10 craziest x86 assembly language instructions. You have to admit that the percentage of assembly language programmers is decreasing every year, so this isn’t going to have mass appeal, but if you are interested in assembly or CPU architecture, this is a fun way to kill 15 minutes.

Some would say that all x86 instructions are crazy, especially if you are accustomed to reduced instruction set computers. The x86, like other non-RISC processors, has everything but the kitchen sink. Some of these instructions might help you get that last 10 nanoseconds shaved off a time-critical loop.

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“MORPH” LED Ball Is A There-Is-No-Spoon, Reality-Bending Art Installation

February 25, 2021 by 16 Comments

Marvelously conceived and exquisitely executed, this huge ball made up of hexagon tiles combines the best of blinky LEDs and animatronics into one amorphic ball.

The creation of [Nicholas Perillo] of Augmentl along with [MindBuffer], full details of the “morph v2” project have not yet been published. However, some tantilizing build progress is documented on [Nicholas’] Insta — most especially through the snapshots in the story thread spanning the last seven months. The scope of the project is brought into focus with time lapse video of hundreds of heat-set inserts, bundles of twisted wire, a pile of 1500 sliding rails, cases full of custom-order stepper motors, and thick cuts of copper bus bars to feed power up the shaft and out to the panels.

The demo video after the break is mesmerizing, shot by [nburdy] during a demo at MotionLab Berlin where it was built. Each hex tile is backed by numerous LEDs and a stepper motor assembly that lets it move in and out from the center of the ball. Somehow it manages to look as though it’s flowing, as they eye doesn’t pick up spaces opening between tiles as they are extended.

The Twitter thread fills in some of the juicy details: “486 stepper motors, 86,000 LEDs and a 5 channel granular synth engine (written by @_hobson_ no less, in @rustlang of course).” The build also includes speakers mounted in the core of the ball, hidden behind the moving LED hexes. The result is an artistic assault on reality, as the highly coordinated combinations of light, sound, and motion make this feel alive, otherwordly, or simply a glitch in the matrix. Watching the renders of what animations will look like, then seeing it on the real thing drives home the point that practical effects can still snap us out of our 21st-century computer-generated graphics trance.

It’s relatively easy to throw thousands of LEDs into a project these days, as PCBA just applies robots to the manufacturing problem. But motion remains a huge challenge beyond a handful of moving parts. But the Times Square billboard from a few years ago and the Morph ball both show it’s worth it.

As you’ve guessed from the name, this is the second Morph ball the team has collaborated on. Check out details of v1, a beach ball sized moving LED ball.

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Electric Airboat For Getting You Across Thin Ice

February 25, 2021 by 20 Comments

Even with all the technological progress civilization has made, weather and seasons still have a major impact on our lives. [John de Hosson] owns a cabin on an island in a Swedish lake, and reaching it involves crossing 500 m of water. In summer this is done with a conventional boat, and in winter they can simply walk across the thick ice, but neither of these is an option on thin ice in the spring or fall. To solve this [John] built an electric airboat, and it looks like a ton of fun in the video after the break

The construction is simple but functional. A 3.3 m flat-bottomed aluminum boat has used a base, and an aluminum frame was bolted on for the motor and propeller. The motor is an 18 kW brushless motor, with a 160 cm/63-inch carbon fiber propeller. Power comes via a 1000 A ESC from a 100V 3.7 kWh Lipo pack mounted in a plastic box. Steering is very similar to a normal airboat, with a pair of air rudders behind the propeller, controlled by a steering lever next to the driver’s seat. The throttle is an RC controller with the receiver wired to the ESC.

Performance is excellent, and it accelerates well on ice and slush, even with two people on board. [John] still plans to make several improvements, with a full safety cage around the propeller being at the top of the list. He is also concerned that it will capsize on the water with the narrow hull, so a wider hull is planned. [John] has already bought a large steering servo to allow full remote control for moving cargo, with the addition of an FPV system. We would also add an emergency kill switch and waterproofing for the electronics to the list of upgrades. It looks as though the battery box is already removable, which is perfect for getting it out of the cold when not in use.

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