World’s Worst I/O Dock Doesn’t Deserve Elegant Fix

Even spendy commercial products can end up being lemons. This is something [Mike Buss] is familiar with, as he had the misfortune of being stuck using what he declares is the world’s worst USB hub, and it’s not even a mystery discount device from overseas: it’s an HP Thunderbolt Dock G2. It is a sort of combination I/O dock and USB hub, and it caused him no end of frustration until he “fixed” it with a crude workaround.

The problems with [Mike]’s dock come down to two major issues. The first is that the USB-C connection will, if moved even the slightest amount, instantly trigger a disconnect from the host computer. Frankly, that sounds like a defect, but that’s not all. The other issue is that the whole top of the device is actually a giant, hyper-sensitive button. Even a stern gaze seems to be enough to cause it to activate. What does the button do? It puts the host computer to sleep; something that we all agree should suffer from as few false activations as possible.

We’ll spoil the surprise by revealing that the “fix” was nothing more than putting a 3D printed enclosure around the troublesome device, as shown in the image above. Keeping the dock covered and perfectly still at least prevents the two aforementioned issues, and that’s good enough for [Mike].

The curious part of all this is just how badly the device’s design affected normal use. We’d suspect a defect or malfunction, but a cursory search of reviews online suggests [Mike]’s experience isn’t unique. It’s certainly not the first poorly-designed product we’ve seen fixed by a new enclosure, but some problems just aren’t worth the effort of a more elegant solution.

Fail Of The Week: Alternator Powered Electric Go-Kart Doesn’t Go

What do you give a six-year-old who loves going fast but doesn’t like loud noises? Convert a gas go-kart to electric of course! (Video, embedded below.) That goal started [Robert Dunn] of Aging Wheels down a long path toward a go-kart that almost, but doesn’t quite… work.

If you’ve watched any of [Robert’s] videos, you know he doesn’t take the easy path. The man owns a Trabant and Reliant Robin after all. Rather than buy a battery pack, he built his own 5S24P pack from individual LiFePO4 cells. Those cells generally are spot welded, so [Robert] built an Arduino-controlled heirloom-quality spot welder. Now while the welder could handle thin nickel strips, it wasn’t up the task of welding high current nickel-plated copper. When attempts at a solution failed, [Robert] built a system of clamped copper bus bars to handle the high current connections for the batteries.

If batteries weren’t hard enough, [Robert] also decided he wasn’t going to use an off-the-shelf motor for this project. He converted a car alternator to operate as a brushless motor. We’ve covered projects using this sort of conversion before. Our own [Jenny List] even wrote a tutorial on it. [Robert] unfortunately has had no end of trouble with his build.

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Fail Of The Week: Mistaking Units For Values

Usually when we post a Fail Of The Week, it’s a heroic tale of a project made with the best of intentions that somehow failed to hit its mark. The communicator that didn’t, or the 3D-printed linkage that pushed the boundaries of squirted plastic a little bit too far. But today we’re bringing you something from a source that should be above reproach, thanks to [Boldport] bringing us a Twitter conversation between [Stargirl] and [Ticktok] about a Texas Instruments datasheet.

The SN65220 schematic
The SN65220 schematic

The SN65220 is a suppressor chip for USB ports, designed to protect whatever the USB hardware is from voltage spikes. You probably have several of them without realising it, the tiny six-pin package nestling on the PCB next to the USB connector. Its data sheet reveals that it needs a resistor network between it and the USB device it protects, and it’s this that is the source of the fail.

There are two resistors, a 15kO and a 27O, 15k ohms, and 270 ohms, right? Looking more closely though, that 27O is not 270 with a zero, but 27O with a capital “O”, so in fact 27 ohms.

The symbol for resistance has for many decades been an uppercase Greek Omega, or Ω. It’s understood that sometimes a typeface doesn’t contain Greek letters, so there is a widely used convention of using an uppercase “R” to represent it, followed by a “K” for kilo-ohms, an “M” for mega-ohms, and so on. Thus a 270 ohm resistor will often be written as 270R, and 270 kilo-ohm one as 270K. In the case of a fractional value the convention is to put the fraction after the letter, so for example 2.7kilo-ohms becomes 2K7. For some reason the editor of the TI datasheet has taken it upon themselves to use an uppercase “O” to represent “Ohms”, leading to ambiguity over values below 1 kilo-ohm.

We can’t imagine an engineer would have made that choice so we’re looking towards their publishing department on this one, and meanwhile we wonder how many USB devices have gone to manufacture with a 270R resistor in their data path. After all, putting the wrong resistor in can affect any of us.

Fail Of The Week: Putting Guitar Strings On A Piano

The piano is a bit of an oddball within the string instrument family. Apart from rarely seeing people carry one around on the bus or use its case to discretely conceal a Tommy Gun, the way the strings are engaged in the first place — by having little hammers attached to each key knock the sound of of them — is rather unique compared to the usual finger or bow movement. Still, it is a string instrument, so it’s only natural to wonder what a piano would sound like if it was equipped with guitar strings instead of piano wire. Well, [Mattias Krantz] went on to actually find out the hard way, and shows the results in this video.

After a brief encounter with a bolt cutter, the point of no return was reached soon on. Now, the average piano has 88 keys, and depending on the note, a single key might have up to three strings involved at once. In case of [Mattias]’ piano — which, in his defense, has certainly seen better days — a total of 210 strings had to be replaced for the experiment. Guitars on the other hand have only six, so not only did he need 35 packs of guitar strings, the gauge and length variety is quite limited on top. What may sound like a futile endeavor from the beginning didn’t get much better over time, and at some point, the strings weren’t long enough anymore and he had to tie them together. Along with some inevitable breakage, he unfortunately ran out of strings and couldn’t finish the entire piano, though it seems he still managed to roughly cover a guitar’s frequency range, so that’s an appropriate result.

We’re not sure if [Mattias] ever expected this to actually work, but it kinda does — there is at least some real sound. Are the results more than questionable though? Oh absolutely, but we have to admire the audacity and perseverance he showed to actually pull through with this. It took him 28 hours just to get the guitar strings on, and another good amount of time to actually get them all in tune. Did it pay off? Well, that depends how you look at it. It definitely satisfied his and other’s curiosity, and the piano produces some really unique and interesting sounds now — but check for yourself in the video after the break. But that might not be for everyone, so luckily there are less final ways to change a piano’s sound. And worst case, you can always just turn it into a workbench.

(Thanks for the tip, [Keith])

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3D Printed Speakers With Many Lessons Learned

Although we all wish that our projects would turn out perfect with no hiccups, the lessons learned from a frustrating project can sometimes be more valuable than the project itself. [Thomas Sanladerer] found this to be the case while trying to build the five satellite speakers for a 5.1 surround sound system, and fortunately shared the entire process with us in all its messy glory.

[Thomas] wanted something a little more attractive than simple rectangular boxes, so he settled on a very nice curved design with few flat faces and no sharp corners, 3D printed in PLA. Inside each is an affordable broadband speaker driver and tweeter, with a crossover circuit to improve the sound quality and protect the drivers. The manufacturer of the drivers, Visatron, provides very nice speaker simulation software to select the appropriate drivers and design the crossover circuit. The front of each speaker consisted of a 3D printed frame, covered with material from a cut-up T-shirt. These covers attach to the main body using magnets and really look the part.

After printing, [Thomas] soaked all the parts in water to clean of the PVA support structures but discovered too late that the outer surfaces are not watertight and a lot of water had seeped into the parts. In an attempt to dry them he left them in the sun for a while which ended up warping some parts, so he had to reprint them anyway. The main bodies were printed in two parts and then glued together. This required a lot of sanding to smooth out the glue joints, and many cycles of paint and sanding to get rid of the layer lines. When assembling the different pieces, he found that many parts did not fit together, which he suspects was caused by incorrect calibration on the delta-bot printer he was using.

In the end, the build took almost two years, as [Thomas] needed breaks between all the frustration, and eventually only used one of the speakers. We’re glad he shared the messy parts of the project, which will hopefully spare someone else a bit of trouble in a project.

Listening to a high-quality audio setup is always a pleasure, and we’ve covered several projects from audiophiles, including affordable DML speakers, and 3D printed speaker drivers.

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Fail Of The Week: Taking Apart A Tesla Battery

It takes a lot of energy to push a car-sized object a few hundred miles. Either a few gallons of gasoline or several thousand lithium batteries will get the job done. That’s certainly a lot of batteries, and a lot more potential to be unlocked for their use than hurling chunks of metal around on wheels. If you have an idea for how to better use those batteries for something else, that’s certainly an option, although it’s not always quite as easy as it seems.

In this video, [Kerry] at [EVEngineering] has acquired a Tesla Model 3 battery pack and begins to take it apart. Unlike other Tesla batteries, and even more unlike Leaf or Prius packs, the Model 3 battery is extremely difficult to work with. As a manufacturing cost savings measure, it seems that Tesla found out that gluing the individual cells together would be less expensive compared to other methods where the cells are more modular and serviceable. That means that to remove the individual cells without damaging them, several layers of glue and plastic have to be removed before you can start hammering the cells out with a PEX wedge and a hammer. This method tends to be extremely time consuming.

If you just happen to have a Model 3 battery lying around, [Kerry] notes that it is possible to reuse the cells if you have the time, but doesn’t recommend it unless you really need the energy density found in these 21700 cells. Apparently they are not easy to find outside of Model 3 packs, and either way, it seems as though using a battery from a Nissan Leaf might be a whole lot easier anyway.

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Fail Of The Week: Supercapacitor Spot Welder

[Julian] needed to weld a bit of nickel to some steel and decided to use a spot welding technique. Of course he didn’t have a spot welder sitting around. Since these are fairly simple machines so [Julian] set out to build a spot welder using a charged supercapacitor. The fundamentals all seem to be there — the supercap is a 100 Farad unit and with a charge of 2.6V, that works out to over 300 joules — yet it simply doesn’t work.

The problem is in how the discharge energy is being directed. Just using the capacitor would cause the charge to flow out as a spark when you got near the point to discharge. To combat this, [Julian] put a microswitch between the capacitor and the copper point he expected to use as the welding tip. The microswitch, of course, is probably not the best for carrying a large surge of current, so we suspect that may be part of why he didn’t get great results.

The other thing we noticed is that he used a single point and used the workpiece as a ground return. Most spot welders use two points near each other or on each side of the workpiece. The current from the capacitor is probably just absorbed by the relatively large piece of metal.

The second video below from [American Tech] shows a 500F capacitor doing spot welding with little more than two wires and it seems to work. Hackaday’s own [Sean Boyce] even made one out of some whopping 3000F caps. It did work, although he’s been pursuing improvements.

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