We aren’t sure if you really need lasers to build [HoPE’s] laser harp. It is little more than some photocells and has an Arduino generate tones based on the signals. Still, you need to excite the photocells somehow, and lasers are cheap enough these days.
Mechanically, the device is a pretty large wooden structure. There are six lasers aligned to six light sensors. Each sensor is read by an analog input pin on an Arduino armed with a music-generation shield. We’ve seen plenty of these in the past, but the simplicity of this one is engaging.
Raise you’re hand if you’ve ever soldered directly to a battery even though you know better. We’ve all been there. Sometimes we get away with it when we have a small pack and don’t care about longevity. But when [Robert Dunn] needed to build a battery pack out of about 120 Lithium Ion cells, he knew that he had to do it The Right Way and use a battery spot welder. Of course, buying one is too simple for a hacker like [Robert]. And so it was that he decided to Build a Spot Welder from an old Microwave Oven and way too much mahogany, which you can view below the break.
Spot Welding leaves two familiar divots in the attached tab, which can be soldered or welded as need.
For the unfamiliar, a battery spot welder is the magical device that attaches tabs to rechargeable batteries. You’ll notice that all battery packs with cylindrical cells have a tab with two small dimples. These dimples are where high amperage electricity quickly heats the battery terminal and the tab until they’re red hot, welding them together. The operation is done and over in less than a second, well before any heat damage can be done. The tab can then be soldered to or spot welded to another cell.
One of the most critical parts of spot welding batteries is timing. While [Robert Dunn] admits that a 555 timer or even just a manual switch and relay could have done the job, he opted for an Arduino Uno with a 4 character 7 segment LED display that shows the welding time in milliseconds. A 3d printed trigger and welder handle wrap up the hardware nicely.
The build is topped off by a custom mahogany enclosure that is quite a bit overdone. But if one has the wood, the time, the tools and skills (and a YouTube channel perhaps?) there’s no reason not to put in the extra effort! [Robert]’s resulting build is almost too nice, but it’ll certainly get the job done.
Of course, spot welders are almost standard fare here at Hackaday, and we’ve covered The Good, The Bad, and The Solar. Do you have a battery welder project that deserves a spot in Hackaday’s rotation? By all means, send it over to the Tip Line!
After last year’s Tesla Battery Day presentation and the flurry of information that came out of it, [The Limiting Factor] spent many months researching the countless topics behind Tesla’s announced plans, the resource markets for everything from lithium to copper and cobalt, and what all of this means for electrical vehicles (EVs) as well as batteries for both battery-electric vehicles (BEVs) and power storage.
A number of these changes are immediate, such as the use of battery packs as a structural element to save the weight of a supporting structure, while others such as the shift away from cobalt in battery cathodes being a more long-term prospective, along with the plans for Tesla to set up its own lithium clay mining operation in the US. Also impossible to pin down: when the famous ‘tabless’ 4680 cells that Tesla plans to use instead of the current 18650 cells will be mass-produced and when they will enable the promised 16% increase.
Even so, in the over 1 hour long video (also linked below after the break), the overall perspective seems fairly optimistic, with LFP (lithium iron phosphate) batteries also getting a shout out. One obvious indication of process to point out is that the cobalt-free battery is already used in Model 3 Teslas, most commonly in Chinese models.
Maritime shipping is big business, with gigantic container ships responsible for moving the vast majority of the world’s goods from point A to points B, C and D. Of course, there’s a significant environmental impact from all this activity, something ill befitting the cleaner, cooler world we hope the future will be. Thus, alternatives to the fossil fuel burning ships of old must be found. To that end, Norwegian company Yara International has developed a zero-emission ship by the name of Yara Birkeland, which aims to show the way forward into a world of electric, autonomous sea transport.
There are many scanners — both commercial and homemade — that can take a variety of scans or images of a 3D object and convert it into something like a 3D printable file. When the process works, it works well, but the results can be finicky at best and will require a lot of manual tuning. According to [Samuel Garbett], you might as well just draw your own model using Blender. He shows you how using a Red Bull can which, granted, isn’t exactly the most complicated thing ever, but it isn’t the simplest either.
He does take one photo of the can, so there is a camera involved at some point. He also takes measurements using calipers, something you probably already have laying around.
Since it is just a can, there aren’t many required pictures or measurements as, say, a starship model. Once you have the measurements, of course, you could use the tool of your choice and since we aren’t very adept with Blender, we might have used something we think is easier like FreeCAD or OpenSCAD. However, Blender has a lot of power, so we suspect making the jump from can to the USS Enterprise might be more realistic for a Blender user.
Looking across your hard drive and GitHub, you might find hundreds of notes and skeletons of Git repositories. A veritable graveyard of software side projects. The typical flow for many of these projects is: get an idea, ruminate on the idea until it becomes exciting, eventually becoming more exciting than the current side project, notes are captured, a repository is created, and work begins at a blistering pace as the focus and excitement are there. There might be some rewrites or some changes in direction. Questions of whether the project is worthwhile or “what even should this project actually be” start to arise. Eventually, enthusiasm wanes as these questions continue to multiply. Progress slows as the path forward seems less clear-cut as it once did. The project is either sunset with a mournful promise to someday return or quietly put aside as something new and exciting comes to take its place. Sound familiar? Perhaps not, but the principles here could be helpful.
This particular article is largely a piece of opinion from one engineer to another. It’s about engineering the process by which you design a project to have better outcomes. There are many reasons why a project could be shelved or scrapped and not all of them are from a lack of clear project definition. In the case where it isn’t clear what the project is, it can be helpful to think about it in a more holistic/meta sense. There are two types of personal projects in broad strokes: technology demos and products.
If you look around your desk right now, odds are you’ll see a 7-segment display or two showing you some vital information like the time or today’s weather. But think of how much information you could see with over 1,100 digits, like with [Chris Combs’] 7200-segment display.
For [Chris], this project started the same way that many of our projects start; finding components that were too good of a deal to pass up on. For just “a song or two plus shipping”, he was the proud owner of two boxes of 18:88 7-segment displays, 500 modules in total. Rather than sitting and using up precious shelf space, [Chris] decided to turn them into something fancy he could hang on the wall.
The IS31FL3733 can produce 8 levels of dimming 8-bit PWM, allowing [Chris] to display in grayscaleThe first challenge was trying to somehow get a signal to all of the individual segments. Solutions exist for running a handful of displays in one device, but there are certainly no off-the-shelf solutions for this many. Even the possible 16 addresses of the IS31FL3733 driver IC [Chris] chose for this project were not enough, so he had to get creative. Fearing potential capacitance issues with simply using an i2C multiplexer, he instead opted to run 3 different i2C busses off of a Raspberry Pi 4, to interface with all 48 controllers.
The second challenge was how to actually wire everything up. The finished display comes out to 26 inches across by 20.5 inches tall, much too large for a single PCB. Instead, [Chris] opted to design a series of self-contained panels, each with 6 of the display modules and an IS31FL3733 to drive them. While the multiplexing arrangement did leave space for more segments on each panel, he opted to go for this arrangement as it resulted in a nice, clean, 4:3 aspect ratio for the final display.
The end result was a unique and beautiful piece, which Chris titled “One-to-Many”. He uses it to display imagery and art related to the inevitability of automation, machines replacing humans, and other “nice heartwarming stuff like that”, as he puts it. There’a video after the break, but if you are interested in seeing the display for yourself, it will be on display at the VisArt’s Concourse Gallery in Rockville, MD from September 3 to October 17, 2021. More info on [Chris’s] website.
