Row Your Bike To China

If you’re a fan of endurance racing motor vehicles, there’s one that puts the 24 Hours of Le Mans, the Dakar Rally, and the Baja 1000 to shame, and the race doesn’t even involve cars. Indeed, the vehicles used for this massive trek from France to China are electric bicycles, powered only by solar panels. This is the epic Sun Trip endurance race, and one of its competitors built a unique tandem bike that is powered both by pedaling, rowing, and the solar panels.

The tandem bike is interesting on its own since the atypical design uses a back-to-back layout which means one person is facing backward, but the storage space is dramatically increased over the normal forward-facing layout. The person in the rear doesn’t pedal, though. [Justin_le] built an upper-body-powered rowing station for that spot so that the person riding back there can rest their legs but still help propel the vehicle. Of course, there’s also a solar panel roof so the two riders can pedal and row in the shade, which includes MPPT and solar tracking which drives a small electric motor on board as well.

This race started in June but is still going on. There’s a live GPS feed so you can keep up with the teams, and if you get really inspired you can go ahead and sign up for the 2019 race as well. This particular bike was also featured on Radio Canada as well if you’d like to learn more about it.

Thanks to [Arthur] for the tip!

Fail of the Week: When Good Foundries Go Bad

Like many of us, [Tony] was entranced by the idea of casting metal, and set about building the tools he’d need to melt aluminum for lost-PLA casting. Little did he know that he was about to exceed the limits of his system and melt a hole in his patio.

[Tony]’s tale of woe begins innocently enough, and where it usually begins for wannabe metal casters: with [The King of Random]’s homemade foundry-in-a-bucket. It’s just a steel pail with a homebrew refractory lining poured in place, with a hole near the bottom to act as a nozzle for forced air, or tuyère. [Tony]’s build followed the plans pretty faithfully, but lacking the spent fire extinguisher [The King] used for a crucible in the original build, he improvised and used the bottom of an old propane cylinder. A test firing with barbecue charcoal sort of worked, but it was clear that more heat was needed. So [Tony] got hold of some fine Welsh anthracite coal, which is where the fun began. With the extra heat, the foundry became a mini-blast furnace that melted the thin steel crucible, dumping the molten aluminum into the raging coal fire. The video below shows the near catastrophe, and we hope that once [Tony] changed his pants, he hustled off to buy a cheap graphite or ceramic crucible for the next firing.

All kidding aside, this is a vivid reminder of the stakes when something unexpected (or entirely predictable) goes wrong, and the need to be prepared to deal with it. A bucket of dry sand to smother a fire might be a good idea, and protective clothing is a must. And it pays to manage your work area to minimize potential collateral damage, too — we doubt that patio will ever be the same again.

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Global Radio Direction Finding in Your Browser

Radio direction finding is one of those things that most Hackaday readers are likely to be familiar with at least on a conceptual level, but probably without much first-hand experience. After all it’s not everyday that you need to track down a rogue signal, let alone have access to the infrastructure necessary to triangulate its position. But thanks to the wonders of the Internet, at least the latter excuse is now a bit less valid.

Triangulated location of “The Buzzer”

The RTL-SDR Blog has run a very interesting article wherein they describe how the global network of Internet-connected KiwiSDR radios can be used for worldwide radio direction finding. If you’ve got a target in mind, and the time to fiddle around with the web-based SDR user interface, you now have access to the kind of technology that’s usually reserved for world superpowers. Indeed, the blog post claims this is the first time such capability has been put in the hands of the unwashed masses. Let’s try not to mess this up.

To start with, you should have a rough idea of where the signal is originating from. It doesn’t have to be exact, but you want to at least know which country to look in. Then you pick one of the nearby public KiwiSDR stations and tune the frequency you’re after. Repeat the process for a few more stations. In theory the more stations you have the better, but technically three should be enough to get you pretty close.

With your receiving stations selected, the system will then start Time Difference of Arrival (TDoA) sampling. This technique compares the time the signal arrives at each station in relation to the KiwiSDR’s GPS synchronized clock. With enough of this data from multiple stations, it can estimate the origin of the signal based on how long it takes to reach different parts of the globe.

It’s not perfect, but it’s pretty impressive for a community run project. The blog post goes on to give examples of both known and unknown signals they were able to triangulate with surprising accuracy: from the US Navy’s VLF submarine transmitter in Seattle, Washington to the mysterious “Buzzer” number station hidden somewhere in Russia.

We’ve covered small-scale triangulation using Wi-Fi, and even a project that aimed to use drones to home in on rescue beacons, but the scale of the KiwiSDR TDoA system is really on a whole new level. Use it wisely.

Replace Old Electrolytics? Not So Fast… Maybe

[CuriousMarc] was restoring an old Model 19 TeleType. The design for these dates back to the 1930s, and they are built like tanks (well, except for the ones built during the war with parts using cheaper metals like zinc). Along the way, he restored a hefty tube-based power supply that had two very large electrolytic capacitors. These dated from the 1950s, and common wisdom says you should always replace old electrolytics because they don’t age well and could damage the assembly if powered up. [Marc] didn’t agree with common wisdom, and he made a video to defend his assertion which you can see below.

If you look at the construction of electrolytic capacitors, one plate of the capacitor is actually a thin layer that is formed electrically. In some cases, a capacitor with this plate is damaged can be reformed either by deliberate application of a constant current or possibly even just in normal operation.

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3D Printer Guardian Watches for Worst-case Failures

Some devices have one job to do, but that job can have many facets. To [jmcservv], an example of this is the job of protecting against worst-case failures in a 3D printer, and it led him to develop the 3D Printer Watchdog Guardian. When it comes to fire, secondary protection is the name of the game because it’s one thing to detect thermal runaway and turn off a heater, but what if that isn’t enough? The MOSFET controlling the heater could have failed closed and can no longer be turned off in a normal sense. In such cases, some kind of backup is needed. Of course, a protection system should also notify an operator of any serious problem, but what’s the best way to do that? These are the kinds of issues that [jmcservv] is working to address with his watchdog, which not only keeps a careful eye on any heating elements in the system, but can take a variety of actions as a result.

Some outcomes (like fire) are bad enough that it’s worth the extra work and cost of additional protection, and that’s the thinking that has led [jmcservv] to submit his watchdog system for The Hackaday Prize.

Review: SMD Tweezer Meter or Tweezer Probes For Your Multimeter?

It’s remarkable how tiny electronics have become. Heaven knows what an old-timer whose experience started with tubes must think, to go from solder tags to SMD in a lifetime is some journey. Even  the generation that started with discrete transistors has lived through an incredible shift. But it’s true, SMD components are tiny, and that presents a challenge aside from the one you’ll face when soldering them. Identifying and measuring the value of a chip component too small to have any writing upon it becomes almost impossible with a pair of standard test probes.

Happily the test equipment manufacturers have risen to the challenge, and produced all sorts of meters designed for SMD work that have a pair of tweezers instead of test prods. When I was looking for one I did my usual thing when it comes to Hackaday reviews. I looked at the budget end of the market, and bought an inexpensive Chinese model for about £16($21). And since I was browsing tweezers I couldn’t resist adding another purchase to my order. I found a pair of tweezer test probes for my multimeter which cost me just over a pound ($1.30) and would provide a useful comparison. For working with SMD components in situ, do you even need the special meter?

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Human-Computer Interface Challenge: Change How We Interact with Computers, Win Prizes

Pay no attention to the man behind the curtain. It’s a quote from the Wizard of Oz but also an interesting way to look at our interactions with electronics. The most natural interactions free us from thinking about the ones and zeros behind them. Your next challenge is to build an innovative interface for humans to talk to machines and machines to talk to humans. This is the Human-Computer Interface Challenge!

The Next Gen of HCI

A Human-Computer Interface (or HCI) is what we use to control computers and what they use to control us get information to us. HCIs have been evolving since the beginning. The most recent breakthroughs include touchscreens and natural-language voice interaction. But HCI goes beyond the obvious. The Nest thermostat used a novel approach to learning your habits by observing times and days that people are near it, and when the temperature setting is changed. This sort of behavior feels more like the future than having to program specific times for temperature control adjustments. But of course we need to go much further.

You don’t need to start from scratch. There are all kinds of great technologies out there offering APIs that let you harness voice commands, recognize gestures, and build on existing data sets. There are chips that make touch sensing a breeze, and open source software suites that let you get up and running with computer vision. The important thing is the idea: find something that should feel more intuitive, more fun, and more natural.

The Best Interfaces Have Yet to Be Dreamed Up

No HCI is too simple; a subtle cue that makes sure you don’t miss garbage collection day can make your day. Of course no idea is too complex; who among you will work on a well-spoken personal assistant that puts Jarvis to shame? We just saw that computers sound just like people if you only tell them to make random pauses while speaking. There’s a ton of low-hanging fruit in this field waiting to be discovered.

An HCI can be in an unexpected place, or leverage interactions not yet widely used like olfactory or galvanic responses.  A good example of this is the Medium Machine which is pictured above. It stimulates the muscles in your forearm, causing your finger to press the button. The application is up to you, and we really like it that Peter mentions that Medium Machine reaches for something that wouldn’t normally come to mind when you think about these interfaces; something that hasn’t been dreamed up yet. Get creative, get silly, have some fun, and show us how technology can be a copilot and not a dimwitted sidekick.

You have until August 27th to put your entry up on Hackaday.io. The top twenty entries will each get $1,000 and go on to the finals where cash prizes of $50,000, $20,000, $15,000, $10,000, and $5,000 await.