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July 17 2018

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.

July 16 2018

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.

Of course, [Marc] agrees sometimes a capacitor is done for and has to be replaced. But he is saying that if you test it and it is good enough, it will get better with use. He also shows a capacitor that is starting to fail in a way such that he did replace it.

We get the idea [Marc] was a bit peeved at the comments on his previous video about his failure to replace the capacitors. He’ll get no sympathy from any Hackaday authors though. We have covered how to reform electrolytics before. We’ve also examined the insides of different capacitors, which is a good start to reasoning about how they might fail.

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.

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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?

A Packet Full Of Tweezers Arrives

Clipping these tweezers onto SMD devices is easy enough. Clipping these tweezers onto SMD devices is easy enough.

So in due course my package from Shenzhen arrived, what had I bought? The tweezer test prods were of anonymous origin, but the meter came in a blister pack with a manufacturer’s name and model number. This was it seemed a Chinese-language package, but a bit of Google Translate work revealed it to be a Shenzhen Binjiang BM8910 (translated). Opening the package revealed a CR2032 battery for it, plus a Chinese warranty card and a folded set of English instructions. Installing the battery produced an instant power-on, with the meter entering a scanning mode trying to identify what was across its terminals.

You can tell a lot about the quality of an imported product like this one by the quality of its instructions. Those for the BM8910 are a pleasant surprise, with mostly decent English and well-presented diagrams. The unit itself is about the size of a chunky marker pen, yellow plastic with an LCD display, a couple of buttons, and the Chinese for “Chip resistor/diode/capacitor intelligent tester” according to Google Translate on top. It parts in the middle, and one end slides off to reveal the tweezers themselves, which are insulated spring steel with pointed probes attached to their ends. The instruction leaflet claims that these are gold-plated, I have to say it doesn’t look very golden to me. Aside from this, the overall quality and feel of its construction is good, this may not have cost much but it does not feel too cheap.

Turning it on by pressing the “func” button, and it enters an automatic mode in which it tries to identify the component in the tweezer as a resistor, capacitor, or diode, and give a reading. Pressing “func” repeatedly steps it through individual autoranging resistance, continuity, diode tester, and capacitance modes, and holding the button down turns it off. The other button is a “hold” button, convenient for retaining a reading.

So having investigated the BM8910, I set to with a variety of SMD boards and modules  around my bench. Gripping a part was easy enough, though 0201s require a little care as you might expect. and in most cases the instrument correctly identified their function and value. It becomes a quick way of determining manufacturing quality, for you soon see what tolerance components have been used by the variance in their values. It is worth noting that the continuity function does not have the buzzer you might expect.

As a general point, most component measurements seemed unaffected by their placement in-circuit. An LED series resistor on an Arduino, for example read exactly as it should have. But in cases where RC networks affect the perceived value across a component as you might expect the readings it returns can not be trusted as the value of that component. In general it seems to prefer identifying the resistance of whatever circuit  it sees, and if that includes an inductor it defaults to the DC resistance of that component.

I’d say that if you’re in the market for a not-too-expensive SMD tweezer tester, SZBJ BM8910 is a good option. But this review isn’t over, because I also bought those SMD tweezer test probes for my multimeter. If you’re a really frugal engineer, how do they rack up against a dedicated instrument?

But How About The Basic Option?

You pay not a lot for the tweezer test probes, and to be fair, you get not a lot but what you get isn't bad.You pay not a lot for the tweezer test probes, and to be fair, you get not a lot. But what you get isn’t bad.

For not a lot of money it’s fair not to expect much in the way of quality. These these £1 wonders are functional tweezers with a plastic grip and a single flex about 50cm (1’6″) long that splits into two wires with 4mm plugs for the meter terminals. The tips of the tweezers aren’t as nice as those on the BM8910, being just the plated spring steel of the tweezers themselves. Operation is simple: plug it into the meter, and you’re good to go.

Gripping SMD devices is easy enough, and identifying resistor values is yet again fairly straightforward. The same issues with networks of components apply, and of course you are limited in what you can measure by what your meter is capable of. Mine doesn’t have a capacitance range, so I was only able to compare the two on resistance and diode testing, on which it compared favourably. It was however extremely useful to be able to measure voltages in-circuit with a device powered on, and I suspect that this is what these probes will end up being used for.

Yet again, these tweezers are easy enough to use. Yet again, these tweezers are easy enough to use.

The inexpensive SMD tweezer probes are not the highest quality tool you’ll have on your bench, but they are so cheap that it’s an easy choice to add to your arsenal. They aren’t really as convenient as the dedicated instrument for measuring the values of SMD components, but they do bring all the meter’s capabilities to bear and it’s extremely convenient to be able to measure voltages. Buy a set, you’ll find them useful.

This review started as a comparison between two ways of measuring SMD devices on PCBs, and ended with a recommendation to buy both the decent option and the cheap one if you have that requirement.

Regular readers will have followed the occasional series of reviews here of inexpensive imported tools and test equipment, and will know that sometimes the cheapest in the catalogue can be entertainingly bad. In this case it’s a pleasant surprise that the ultra-cheap probes were useful, but perhaps the key to a successful cheap tool lies in extreme simplicity.

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.

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A Microwave Erector Set

RF design isn’t always easy, especially at higher frequencies. Despite improvements in simulation tools, there’s still no substitute for prototyping and trying out different things. That wasn’t so bad when that meant nailing some nails in a piece of wood and wiring up discrete components. But at today’s microwave frequencies and with today’s IC packaging that simply doesn’t work. Solving this problem is what drives a company called X-Microwave. They have a standard grid pattern PCB for a wide range of RF circuits and accessories to tie them all together. Probably the best way to get a feel for the system is to watch the simple video below. There’s also a free simulator tool worth taking note of that you’ll see in a bit.

Before you get too excited, we’ll warn you that while this stuff is cheap if you need it, it isn’t an impulse buy. The baseboards and probes (the connectors) run from $150 to $300. You can get kits, too, but a bare-bones two-port system is going to start at about $550, which is about $100 off the component parts and includes some extras. Then you need less expensive parts to make the boxes around things if you need them. Oh. Then you also need the PCBs which are not cheap, either. Their prices vary widely as you’d expect, but — for example — we saw amplifiers as low as $80 and as high as nearly $1000. So a complete system could get pretty pricey.

However, if you really need to breadboard RF circuits in the microwave region — they claim the system can get up to 50 GHz — these prices are not unreasonable compared to what you are going to have to do otherwise.

Also, there is a free browser-based simulator you can experiment with which is quite powerful. You do need to register (and while the registration appeared to fail, it actually worked). The backend to the simulator is Genesys Spectrasys, so this is actually a cheap way to get limited access to a very powerful RF simulation tool. It took awhile to figure out, but you can populate the spectrum display at the bottom of the screen by right clicking on any black wire. You can pick behavior models which are ideal or modules that correspond to real-world X-Microwave modules. There’s also an online layout tool for planning your circuit layouts, but that’s not as exciting as the simulator.

This is one of those things that if you need it, it is affordable. If you don’t, then it is priced astronomically. However, it isn’t hard to imagine homebrewing something similar, especially if your frequency needs are more modest. We might suggest the RF Biscuit as a starting point. If you are just too cheap to go this route, you might look into foil tape. We’ve built entire transmitters and receivers using foil tape to create ad hoc “circuit boards.”

Thanks to [RoGeorge] for mentioning this system over on Hackaday.io.

Getting the Lead Out of Lithium Battery Recycling

When that fateful morning comes that your car no longer roars to life with a quick twist of the key, but rather groans its displeasure at the sad state of your ride’s electrical system, your course is clear: you need a new battery. Whether you do it yourself or – perish the thought – farm out the job to someone else, the end result is the same. You get a spanking new lead-acid battery, and the old one is whisked away to be ground up and turned into a new battery in a nearly perfect closed loop system.

Contrast this to what happens to the battery in your laptop when it finally gives up the ghost. Some of us will pop the pack open, find the likely one bad cell, and either fix the pack or repurpose the good cells. But most dead lithium-based battery packs are dropped in the regular trash, or placed in blue recycling bins with the best of intentions but generally end up the landfill anyway.

Why the difference between lead and lithium batteries? What about these two seemingly similar technologies dictates why one battery can have 98% of its material recycled, while the other is cheaper to just toss? And what are the implications down the road, when battery packs from electric vehicles start to enter the waste stream in bulk?

Time + Chemistry = Economics

Understanding the disparity between lead-acid and lithium-ion battery recycling boils down to two major factors: time and chemistry. On the time side of the equation, consider that the big chunky battery under your hood is pretty old technology. Lead-acid batteries have been around for as long as cars have, and then some. As such, they have over a century’s head start on their lithium based cousins in terms of infrastructure. We’ve been using these things forever, and we’ve really dialed in their lifecycle management. From cradle to grave and back to cradle again, lead-acid batteries benefit from an extensive and highly integrated manufacturing and distribution system, one that the lithium-ion industry just has not yet had time to develop. The lead-acid infrastructure goes so far as to often use the exact same trucks that deliver batteries to retailers for the return trip to the recycler.

Time also plays into it via the rapid turnover of automotive batteries. The average car battery lasts about four years, give or take, and since the average lifetime of a car is now about eleven years, each car will likely see three or more batteries over its service life. For electric vehicles and hybrids, the battery pack is designed to last for pretty much the service life of the vehicle, so barring accidents that render the vehicle wrapped around them useless, lithium-ion packs are just not going to enter into the recycling stream nearly as often as lead-acid batteries do. This is somewhat negated by the number of lithium-ion battery packs from consumer products like laptops and power tools; those enter the waste stream far faster than lithium-ion batteries from electric and hybrid vehicles. But those numbers are a rounding error in the equation compared to the number of lead-acid batteries recycled every day.

Lead-acid batteries can be nearly 100% recycled. Source: US Green Technology

As for chemistry, the simpler the mix of materials in an object, the easier it is to recycle. Aluminum cans, which are just aluminum and paint, are incredibly easy to reclaim with the addition of a little heat. Lead-acid batteries are not quite that simple, but they’re close: just lead, lead oxide, and sulfuric acid in a plastic case. Each material in the battery has a simple path from old to new: the lead plates melt easily at low temperatures and can be easily purified, ditto for the PVC that typically makes up the battery’s case, and the sulfuric acid electrolyte can either be diluted and disposed of as wastewater, or the sulfates can be recovered to manufacture new electrolytes or used in the production of other consumer items, such as soaps.

Lithium batteries, on the other hand, have much more complicated chemistries and a mix of materials that don’t work and play well together in an industrial recycling process. A lithium-ion battery is not just lithium but also has cobalt, manganese, iron phosphate, or nickel compounds, not to mention aluminum, copper, and graphite. Not only is the mix of metals more complicated, but their physical form as powders coated onto metal foil makes recovery of each component far more complicated than just throwing it in a furnace.

The electrolyte in a lithium battery is much more complicated too, consisting of lithium salts in volatile organic solvents like ethylene carbonate. This makes the liberated electrolytes much more difficult to deal with as well; no simple dilution and neutralization with a basic solution like sodium bicarbonate will render these compounds safe enough to discharge to a sewer as is the case for lead-acid recycling. Dealing with that adds to the cost of recycling and cuts into the potential profit.

A Hands-Off Process

The mechanical process of recycling is also much easier for lead-acid batteries. In the most advanced recycling plants, used car batteries can literally be chucked into a shredder whole, which pulverizes the plastic cases, releases the electrolyte, and shreds the innards. Process water is added to dilute the sulfuric acid and flush away the plastic bits, which can be skimmed off while letting the lead parts sink. Everything has its own physical path through the process, and human hands need never touch the batteries, which makes for a very economical process that scales well. And even where the process is not entirely automated, the limited number of shapes and sizes of batteries, coupled with their relatively large size, makes orienting the batteries for quick disassembly easy.

Compare this to handling a lithium-ion battery pack. The form factor for these could range from a laptop battery to an old drill-driver battery pack to the guts of a wrecked electric vehicle. While most of these will be loaded with cells like the 18650, each one will differ in size and shape, and the number and orientation of cells within the pack will vary wildly. Most packs will also have some kind of circuit board inside, which requires a separate step to liberate and has to enter a different recycling stream. At least for now, this makes disassembly of lithium-ion packs the work of human hands, which makes it an expensive proposition that scales poorly.

The differences between the effort needed to recycle lead-acid and lithium-ion batteries drive the overall economics of the process. If you look at the price of lithium ($17,000 / ton) versus lead ($2,600 / ton), it would seem that lithium recycling would be more profitable. But if you can’t get the lithium out of batteries effectively, it doesn’t matter how much the stuff would earn. For recyclers, the value proposition is skewed heavily in favor of lead, where huge feedstock volumes and easy extraction methods make recycling a profitable venture. And that’s not to mention the dangers of mixing lithium batteries into the lead-acid recycling stream.

All this leads to the sad fact that currently, 97% of lithium-ion batteries are not recycled. With a huge new input of dead batteries about to hit the waste stream as the first generations of electric and hybrid vehicles reach the end of their service lives, this is going to be a problem we’re going to need to deal with soon. The fact that both lithium and cobalt are sourced from politically unstable regions of the world will probably help skew the economics of recycling such that it makes more sense to recover the minerals rather than commit them in an unusable state to the ground whence they came. Things will likely change, but for now, lithium-ion batteries are a dead end technology.

Acrylic Stencils Help with Component Placement for SMD Assembly

Surface mount is where the action is in the world of DIY PCBs, and deservedly so. SMDs are so much smaller than through-hole components, and fewer holes to drill make surface-mount PCBs easier to manufacture. Reflow soldering is even a snap now thanks to DIY ovens and solder stencils you can get when you order your boards.

So what’s the point of adding another stencil to the surface-mount process? These component placement stencils are [James Bowman]’s solution for speeding up assembly of boards in production runs too small to justify a pick and place robot. [James] finds that placing small components like discrete resistors and caps easy, but struggles with the placement of the larger components, like QFN packaged microcontrollers. Getting such packages lined up exactly is hard when the leads are underneath, and he found repositioning led to smeared solder paste. His acrylic stencils, which are laser-cut from SVGs derived directly from the Eagle files with a script he provides, sandwich the prepped board and let him just drop the big packages into their holes. The acrylic pops off after placement, leaving the components stuck to the solder paste and ready for their trip to the Easy Bake.

[James] claims it really speeds up hand placement in his biggish runs, and it’s a whole lot cheaper than a dedicated robot. But as slick as we think this idea is, a DIY pick and place is still really sweet.

It’s 1984, And You Can’t Afford A Computer. Never Mind, Have This Pop-Up Paper One Instead!

It’s an oft-derided sentiment from a Certain Type of Older Person, that the Youth of Today don’t know how lucky they are with their technology. Back when they were young they were happy with paper and string! Part of the hilarity comes from their often getting the technology itself wrong, for example chastising the youngsters for their iPods and Game Boys when in reality those long-ago-retired devices are edging into the realm of retrotechnology.

But maybe they have a point after all, because paper and string could be pretty good fun to play with. Take the example presented  in a Twitter thread by [Marcin Wichary]. A pop-up book from 1984 that presents the inner workings of a computer in an astounding level of detail, perhaps it stretches the pop-up card designer’s art to the limit, but along the way it makes a fascinating read for any retrocomputing enthusiast. Aside from the pop-up model of the computer with an insertable floppy disk that brings text onto the screen we see at  first, there is a pop-up keyboard with a working key, a peer inside the workings of a floppy disc, a circuit board complete with a paper chip that the reader can insert into a socket, and a simulation of a CRT electron bean using a piece of string. A Twitter thread on a book is not our normal fare, but this one is something special!

Did any of you have this book when you were younger? Perhaps you still have it? We’d love to hear from you in the comments. It’s probably not the type of book we normally review, but we’ve been known to venture slightly outside tech on that front.

Incredible Atari 800XL Case Restoration

If you’ve been hanging around Hackaday for a while, you know that a large portion of the stuff we publish goes above and beyond what most people would consider a reasonable level of time and effort. One could argue that’s sort of the point: the easy way out is rarely the most exciting and interesting route you can take. We, and by extension our readers, are drawn to the projects that someone has really put their heart and soul into. If the person who created the thing wasn’t passionate about it, why should we be?

That being said, on occasion, even we are left in awe about the lengths some people will go to. A perfect example of this is the absolutely insane amount of time and effort [Drygol] has put into restoring an Atari 800XL that looked like it was run over by a truck. Through trial, error, and a bunch of polyester resin, he’s recreated whole sections of the Atari’s case that were missing.

To start the process, [Drygol] used metal rods to bridge the areas where the plastic was completely gone. By heating the rods with a torch and pushing them into the Atari’s case, he was able to create a firm base to work from. Additional rods were then soldered to these and bent, recreating the shape of the original case. With the “skeleton” of the repair in palce, the next step was filling it in.

[Drygol] borrowed an intact Atari 800XL case from a friend, and used that to create a mold of the missing sections from his own case. Most of his rear panel was missing, so it took some experimentation to create such a large mold. In the end he used silicone and a custom built tray that the case could sit in vertically, but he does mention that he never quite solved the problem of degassing the silicone. The mold still worked, but bubbles caused imperfections which needed to be filled in manually during the finishing process.

Using his silicone mold and the same tray, he was then able to pour polyester resin over the wire frame. This got him most of the way to rebuilding the case, but there was still plenty of filler and sanding required before the surface finish started to look half-way decent. When he got towards the very end of the finishing process, he used a mold he created of the case surface texture to roughen up the smooth areas left over from the filling process. Add a bit of custom spray paint, and the end result looks absolutely phenomenal considering the condition it was in originally.

We were already impressed by the work he put in during the first stages of the restoration, but this case repair is really on a whole new level. Between this and the incredible instructional videos [Eric Strebel] has been putting out, we’re really gaining a whole new respect for the power of polyester.

Dual Source Laser Cutter Built Like a Tank, Cuts Most Anything

Laser cutters aren’t the sort of thing that you might think about making at home, but there’s no reason not to if you are careful and do your research. That’s what [Daniele Ingrassia] did with the Laser Duo, an open source laser cutter that has two light sources for cutting various materials. His final product is not a small device: it has a press-formed aluminum case that looks more like a World War I tank than a piece of precision machinery. But that’s for a good reason: you don’t mess about with lasers, especially the 130 Watt CO2 and 75 Watt Yag lasers that the Laser Duo uses.

[Daniele] is going to open-source the entire project, starting with the custom motor controller that he uses, the Satshakit-grbl.  He’s looking to release final plans for the cutter in August after he has duplicated the build at Hamburg University. The two lasers mean that it can cut a wider range of material than most: the CO2 laser can cut or engrave wood, fabric or MDF while the 75W Yag laser can burn its way through harder materials such as brass, stainless steel, copper or marble. This opens up new uses for a laser cutter: it can create PCBs, engrave metal or even make a nice tombstone. The 150 x 100 x 50 cm (about 60 by 40 by 20 inches) working area means that you could also just about do the whole tombstone in one piece.

[Daniele] says that the parts are mostly 3D printed, CNC machined or press formed. The latter might put it beyond the capabilities of the typical home hacker, but most decent sized hackerspaces will have the required capabilities, or know someone who has. We’ve seen lots of build your own laser cutter projects before and hacks to improve the cheap models from Ali Express, but the solid design and capabilities of this one make it a project to watch. In the meantime, you can check out the DuoLaser at the Fab14 conference in Toulouse in late July.

July 15 2018

Hackaday Links: July 15, 2018

Have you tried Altium CircuitMaker? Uh, you probably shouldn’t. [Dave] of EEVBlog fame informs us via a reliable source that CircuitMaker is intentionally crippled by adding a random sleep on high pad-count boards. The hilarious pseudocode suggested on the forum is if ((time.secs % 3) == 0) delayMicroseconds(padCount * ((rand() % 20) + 1));.Now, this is a rumor, however, I would assume [Dave] has a few back channels to Altium. Also, this assertation is supported by the documentation for CircuitStudio, which says, “While there are no ‘hard limits’ per se, the software has been engineered to make it impractical for use with large designs. To this end, the PCB Editor will start to exibit [sic] performance degradation when editing designs containing 5000 pads”. Chalk this up to another win for Fritzing; Fritzing will not slow down your computer on purpose.

Here’s an open challenge to everyone. As reported by [SexyCyborg], XYZPrinting (makers of the da Vinci printer) are patent trolling. This US patent is being used to take 3D printers off of the Amazon marketplace. Here’s the problem: no one can figure out what this patent is actually claiming. There’s something about multiple nozzles, and it might be about reducing nozzle travel, but I’m getting a ‘snap to bed’ vibe from this thing. Experts in 3D printing have no idea what this patent is claiming. The printer in question is the Ender 3, one of the first (actually the third…) China-based Open Source Hardware certified products, and it’s actually the best selling printer on Amazon at this time. I’m talking with Comgrow (the sellers of the Ender 3 on Amazon), and the entire situation is a mess. Look for an update soon.

Tired: Congress shall make no law… abridging the freedom of speech. Wired: But what if that speech is a gun? Wired‘s own Andy Greenberg advances the argument that computer code is not speech, contrary to many court rulings over the past 30 years (see Bernstein v. United States). Here’s the EFF’s amicus brief from the case. Read it. Understand it. Here’s a glowing Stephen Levy piece from 1994 on the export-controlled PGP for reference.

Like integrated circuits and microprocessors? Sure you do. Like drama? Oh boy have we got the thing for you. A week or so ago, ARM launched a website called RISC-V Basics (now unavailable, even from the Internet Archive, but you can try it here). It purports to settle the record on those new chips based on the capital-O Open RISC-V instruction set. In reality, it’s a lot of Fear, Uncertainty, and Doubt. This was an attempt by ARM Holdings to kneecap the upstart RISC-V architecture, but a lot of ARM engineers didn’t like it.

Harvesting Power From Microwave Popcorn

One of the challenges in this year’s Hackaday Prize is Power Harvesting where we’re asking everybody to create something that harvests energy from something. It could be solar, it could be harvesting energy from a falling weight. If you’d like to give a TED talk, it could be harvesting energy from sound waves. It could be harvesting energy from ambient RF, and where’s the best place to harvest ambient RF? That’s right, next to a microwave.

[Jurist]’s entry for the Power Harvesting Challenge in this year’s Hackaday Prize is a simple device that mounts to the front door of a microwave. The design uses a simple PCB antenna to harvest energy, an LTC3108 DC/DC converter that was lying around in a junk drawer, and a bunch of passives to suck down some photons escaping from a microwave. The idea for this whole device is to use the harvested power to send off a message over Bluetooth (or whatever) when the microwave is done. Really, though, this falls right into the ‘because I can’ category of weird builds.

So, does this power harvesting PCB work? The initial tests were iffy because there was no trimming of the antenna and no tuning of the circuit. However, after [Jurist] connected the board to a voltmeter and cooked some beans, he was seeing an entire volt across the circuit. It’s a start, and the beginning of a truly ‘smart’ microwave add-on. Really, though, it’s just cool to see a circuit harvest power from a leaking Faraday cage.

The HackadayPrize2018 is Sponsored by:




Interactive Mandelbrot Set Viewer Runs on FPGAs

The Mandelbrot Set is a mathematical oddity where a simple function creates an infinitely complex landscape that you can literally zoom into forever. Like most people, I’ve downloaded Mandelbrot set viewers and marveled at the infinite whorls and spirals, and then waited while each frame took minutes or hours to render as I zoomed in. [Michael Henning], [Max Rademacher] and [Jonathan Plattner] decided to throw some modern computational muscle at this problem by building an interactive Mandelbrot set viewer using a laptop and two FPGA boards.

The three are students at Cornell, and this was their final project for the Advanced Microcontrollers class. The design is clever: the laptop handles the user interface and renders the final display of the Mandelbrot set. It also sends requests to the FPGA boards that do the number crunching, dividing the required calculations into tiles that are divided between boards. The FPGA boards are TerASIC DE-1 SOC boards that are built around a Cyclone V SOC FPGA chip twinned with 1GB of DDR5 memory. They used two boards, but their modular design means that it would be easy to speed the system up even further by adding additional FPGA boards.

The results are very impressive: the user can zoom in or out and move around in real time, at an impressive resolution of 1600 by 1200 pixels at 60fps. It does slow down when you zoom in, but it’s a remarkable example of how much faster FPGAs can be at this sort of thing than standard CPUs. They have tested it to a maximum depth of 2^260, but their system should be capable of going even further to a remarkable depth of 2^1700. At that depth, the full Mandelbrot set would be nearly as big as the observable universe.

Stepper Motor? Encoder? It’s Both!

We always think it is interesting that a regular DC motor and a generator are about the same thing. Sure, each is optimized for its purpose, but inefficiencies aside, you can use electricity to rotate a shaft or use a rotating shaft to generate electricity. [Andriyf1] has a slightly different trick. He shows how to use a stepper motor as an encoder. You can see a video of the setup below.

It makes sense. If the coils in the stepper can move the shaft, then moving the shaft should induce a current in the coils. He does note that at slow speeds you can miss pulses, however. Again, the device isn’t really optimized for this type of operation.

The circuit uses an opamp-based differential amplifier to read the pulses from the coil. Two opamps on two coils produce a quadrature signal just like a normal encoder. When the shaft turns in one direction, one pulse will lead the other. In the other direction, the lead pulse will be reversed.

There’s code to let an Arduino read the pulses, but we were disappointed it was behind a Patreon paywall. However, there’s plenty of code that will read quadrature on an Arduino or other processors, and that really isn’t the point of the post, anyway. We’ve seen similar hacks done with hard drive motors which are quite similar, by the way.

Drive Big Servos With Ease

CNC machines of all types are a staple here at Hackaday, in that we have featured many CNC builds over the years. But the vast majority of those that we see are of relatively modest size and assembled in a home workshop, using small and readily available components such as small stepper motors. These drives are a world away from those used in industrial CNC machines, where you will find high-voltage servos packing a much greater punch. With good reason: driving a small low-voltage motor is easy while doing the same with a high-voltage servo requires electronics that have hitherto been expensive.

STMBL (for STM32 microprocessor and BrushLess motor) is a servo driver for STM32F4 microcontrollers that is specifically designed to use in retrofit projects to industrial CNC machines that have those high-voltage servos. When assembled, it takes the form of two PCBs arranged in a T configuration over a heatsink, with high-power connectors for the motor terminals, and RJ45s for feedback and serial control. In fact each of the boards has its own STM32, one on the high voltage side and the other on the low voltage, to enable only the simplest of isolated serial connections between them.  A significant variety of combinations of motor and feedback system is supported, making it as versatile as possible a module for those whose CNC needs have escaped their home bench setup. We’re sure we’ll see this module pop up in quite a few builds we show you over the coming years.

Thanks [Andy Pugh] for the tip.

Watney: A Fully 3D Printed Rover Platform

We’re getting to the point that seeing 3D printed parts in a project or hack isn’t as exciting as it was just a few years ago. The proliferation of low-cost desktop 3D printers means that finding a printer to squirt out a few parts for your build isn’t the adventure it once was. Gone are the days of heading to a local hackerspace or college hoping their janky Mendel felt like working that day. But all that really means is that hackers and makers now have the ability to utilize 3D printing even more. Forget printing one or two parts of your design, just print the whole thing.

That’s exactly what [Nik Ivanov] did with Watney, his fully 3D printed rover project. After lamenting that many so-called 3D printed rovers were anything but, he set out to design one that was not only made primarily of printed parts, but was robust enough to put some real work in. Over the course of several design iterations, he built a very capable all-wheel drive platform that needs only some electronics and a handful of M3 screws to leap into action.

As long as you’ve got a 3D printer big enough to handle the roughly 120mm x 190mm dimensions of this bot’s body, you’re well on the way to owning your very own video rover. [Nik] recommends printing everything in PETG, no doubt for its increased strength when it comes to things like the drive gears. Plus it’s low warp, which is really going to help when printing the top and bottom sections of the body. TPU is advised for the tires, but if you don’t have any (or your printer chokes on flexible filaments) you can just wrap the wheels with wide rubber bands.

[Nik] is using a Raspberry Pi Zero W as the brains of the operation, but the beauty of an open platform like this is that you could easily swap out the controls for something else to meet your needs. In addition to the Pi, there’s a L298N H-bridge motor controller to interface with the dual geared motors, as well as a servo to provide tilt for the SainSmart camera module.

We’ve often been surprised at just how expensive commercial robotics platforms can be, so we’re keenly interested in seeing if the availability of designs like this spur on DIY rover development. Though if you’re looking for something a little more rough and tumble, we’ve seen a 3D printed rover that looks combat-ready.

Robot Maps Rooms with Help From iPhone

The Unity engine has been around since Apple started using Intel chips, and has made quite a splash in the gaming world. Unity allows developers to create 2D and 3D games, but there are some other interesting applications of this gaming engine as well. For example, [matthewhallberg] used it to build a robot that can map rooms in 3D.

The impetus for this project was a robotics company that used a series of robots around their business. The robots navigate using computer vision, but couldn’t map the rooms from scratch. They hired [matthewhallberg] to tackle this problem, and this robot is a preliminary result. Using the Unity engine and an iPhone, the robot can perform in one of three modes. The first is a user-controlled mode, the second is object following, and the third is 3D mapping.

The robot seems fairly easy to construct and only carries and iPhone, a Node MCU, some motors, and a battery. Most of the computational work is done remotely, with the robot simply receiving its movement commands from another computer. There’s a lot going on here, software-wise, and a lot of toolkits and software packages to install and communicate with one another, but the video below does a good job of showing what you’ll need and how it all works together. If that’s all too much, there are other robots with a form of computer vision that can get you started into the world of computer vision and mapping.

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