Minimum Viable Quad Build Shows What Starting From Nothing Can Accomplish

August 12, 2021 by 11 Comments

While it’s great to be experienced and have a ton of specialist knowledge needed to solve a problem, there’s something liberating about coming at things from a position of ignorance. Starting at ground zero can lead you down the path less traveled, and reveal solutions that might otherwise not have presented themselves. And, if [Robin Debreuil]’s exploration of the “minimum viable quadcopter” is any example, some pretty fun failure modes too.

The minimum viable product concept is nothing new of course, being a core concept in Lean methodologies and a common practice in many different industries. The idea of building an MVP is to get something working and in the hands of users, who will then give you feedback on everything wrong with it, plus, if you’re lucky, what you got right. That feedback informs the next design, which leads to more feedback and a whole iterative process that should design the perfect widget.

In [Robin]’s case, he wanted to build a quadcopter, but didn’t know where to start. So his first version was as simple as possible: a motor with a propellor and a small LiPo battery. No chassis, no control electronics — nothing. And it worked just about as well as expected. But fixing that problem led to different designs, the process of which was fascinating — we especially liked the quad with opposing motors controlled by mercury tilt switches to sense attitude changes.

In the end, [Robin] took a more conventional tack and used a microcontroller and BetaFlight to get his popsicle stick and hot glue UAV airborne. But the decision to start with a minimum viable design and iterate from there was a powerful learning experience in tune with [Robin]’s off-beat and low-key outlook, which we’ve seen before with his use of bismuth for desoldering and his scratch-off PCBs.

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3D Prints Of Steel — Um — PLA, Rather

August 12, 2021 by 24 Comments

Need a steel beam? You can 3D print PLA beams that are as strong as a steel beam of equivalent weight according to [RepRap]. The Python code for FreeCAD generates a repeating structure especially well suited for belt printers that can print a beam of any length. Keep in mind, of course, given two things that weigh the same, if one is made of steel and the other PLA, the steel one will be physically smaller.

The beams are repeating tetrahedrons which are quite strong with a lot of material on the outer faces to resist bending. Each beam end has a neat block with a wiring hole and a ring of small holes that allow you to mount the beams to things or each other with 30 degree increments of rotation.

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Thrashed, Damaged NES Controller Gets Brought Back To Life

August 11, 2021 by 6 Comments

Electronics might as well be a magical black box to some people. Where some would see a broken NES controller destined for the bin, [Taylor] saw the opportunity for a repair. Thus, the damaged hardware was brought back into useful service.

The controller was bought as part of a job lot, and was heavily damaged when it entered [Taylor]’s ownership. Nintendo built its hardware tough in those days, but the controller had nevertheless been smashed apart, with the case cracked and split and the PCB itself snapped in two.

For someone with basic electronics skills, though, repair was simple. The broken PCB was glued back together with epoxy. The broken traces had solder mask scraped back so that jumper wires could bridge the damaged area and return the circuit to functionality.

From there, it was a simple matter of 3D printing a new case, and the controller was back in service. The case in question was designed by [Alexander Myrman], and has a neat little inset Mario design that’s made visible by paint-filling the inlay.

While it was an easy fix, to the uninitiated in the electronic arts, it might as well be magic. It pays to remember that there are always new people joining the electronics hobby, and projects like these are a great way to learn. It’s also important to note that bringing back old retro hardware is often of great value, as in many cases, they’re not making any more! We see some great restorations around these parts, too. Video after the break.

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Materials For Self Learners

August 11, 2021 by 13 Comments

[João Nuno Carvalho] is a passionate learner. Software engineer by day, he studies all different branches of science and engineering in his spare time. He has organized an impressive list of study / reference materials on a wide variety of subjects that interest him, from aeronautical engineering to quantum mechanics and dozens more in between. In fact, his study lists themselves became so numerous that he collected them into a list of lists, which can be found here on his GitHub repository. These include categories on “How to learn…”

  • Modern Electronics
  • Modern Linux
  • Modern Embedded Systems
  • Mathematics from the ground up
  • Physics from the ground up
  • Modern Compressive Sensing
  • Modern [C, C++, Rust, Python]
  • Modern Machine Learning
  • Modern Aeronautics and Astronautics
  • Guitar on a budget

Another interesting thing we found in his repo was a list of common electrical components. If you can’t remember off the top of your head the part number of common 100 V PNP bipolar transistor, [João]’s list will point you towards a BD136.

It’s quite an impressive list of resources, and we can’t help but wonder how large [Joã0]’s personal library is if it contains even half of the materials from these lists. Check these out if you want to brush up on a topic — they include not only text books and reference volumes, but forums, blogs, YouTube links, etc. On the topic of learning, we wrote a piece back in 2017 on how learning differs between hobbyists and students. Do you have a favorite list-of-lists that you turn to when you want to brush up or learn about a new subject? Let us know in the comments below.

Wireless Earbuds Charge Themselves

August 11, 2021 by 20 Comments

As more and more ports are removed from our smart devices, it seems that we have one of two options available for using peripherals: either buy a dongle to continue to use wired devices, or switch to Bluetooth and deal with perpetually maintaining batteries. If neither of these options suits you, though, there’s a third option available as [befinitiv] shows us in this build where he integrates a tiny solar panel to his earbud case to allow them to automatically charge themselves.

To start, he begins by taking apart the earbud case. For those who still haven’t tried out a set of these, they typically charge only when placed inside of their carrying case, which in his case also contains a small battery itself. Soldering wires directly to the battery allow for the battery to charge without as much electrical loss as he would have had if he had connected to the USB pins on the circuit board. Even then, the cell only generates a single volt so he needs a 5V boost converter to properly charge the battery. That came with its own problem, though, as it wouldn’t fit into the case properly. To solve that issue, he desoldered all of the components and deadbugged them together in order to fit the converter into a much smaller space without having to modify the case in any other way.

With all of that done and the small solar cell attached to the case, [befinitiv] has a smart solution to keep his wireless earbuds topped up without having to carry cables or dongles around every day. We’ve seen plenty of interesting solutions to the problem of various electronics manufacturers removing the ubiquitous 3.5 mm headphone jack too, and not all of them have dealt with this problem without certain other quirks arising as a result.

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3D Printing Steel Parts At Home Via Special Filaments

August 11, 2021 by 31 Comments

Rocket engines are great for producing thrust from fire and fury, but they’re also difficult to make. They require high-strength materials that can withstand the high temperatures involved. [Integza], however, has tried for a long time to 3D print himself a working rocket engine. His latest attempt involves printing an aerospike design out of metal.

Even steel couldn’t hold up to the fury of the rocket exhaust!

The project relies on special metal-impregnated 3D printer filaments. The part can be printed with a regular 3D printer and then fired to leave just the metal behind. The filament can be harsh, so [Integza] uses a ruby nozzle to handle the metal-impregnated material. Processing the material requires a medium-temperature “debinding” stage in a kiln which removes the plastic, before a high-temperature sintering process that bonds the remaining metal particles into a hopefully-contiguous whole. The process worked well for bronze, though was a little trickier for steel.

Armed with a steel aerospike rocket nozzle, [Integza] attempts using the parts with his 3D printed rocket fuel we’ve seen before. The configuration does generate some thrust, and lasts longer than most of [Integza]’s previous efforts, though still succumbs to the intense heat of the rocket exhaust.

Overall, though, it’s a great example of what it takes to print steel parts at home. You’ll need a quality 3D printer, ruby nozzles and a controllable kiln, but it can be done. If you manage to print something awesome, be sure to drop us a line. Video after the break.

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A Stress Monitor Designed Specifically To Help You Work From Home

August 11, 2021 by 10 Comments

There are quite a bit of mixed emotions regarding working from home. Some people love it and are thriving like they haven’t before, but others are having a bit of a hard time with it all. [Brandon] has been working from home for the last 12 years, but even after so many years of managing this type of work culture, he admits that it can still be a little stressful. He says he doesn’t take enough time in between tasks to simply relax and to breathe a little and the day-to-day minutia of his work can drive his stress level up if he doesn’t take some time to calm himself. He figured he could make something to monitor his stress level and remind himself to take a break and the results are pretty impressive.

He develops a system to monitor his heart rate and the ambient noise level in his room and uses these metrics as a measure of stress. If his heart rate or the ambient noise level goes above a certain threshold, then he sends himself a text message reminding himself to relax and take a break. You’ve probably seen people use heart rate as a measure of stress already, but you’re probably less familiar with using sound. [Brandon] basically thought the sound sensor would detect if he starts ranting for prolonged periods of time or if he’s in a Zoom meeting that gets too heated. We thought that was pretty neat.

[Brandon] used an off-the-shelf chest strap heart rate monitor to save himself a bit of time in trying to build his own. The device sends heart rate data to an nRF52840 over Bluetooth and then pushes the data to the cloud using a Blues Wireless Notecard. The Notecard also offers data encryption which gave [Brandon] some added peace of mind knowing his biometric data wasn’t floating around in the cloud without any sort of protection. This certainly isn’t medical-grade encryption, but it gave him a bit of comfort, nonetheless. All that data is processed in his custom-designed web app and when the appropriate thresholds are reached, he sends a text message to himself using Twilio reminding him to relax and unwind for a bit.

For his next iteration, [Brandon] might try making his own heart rate monitor. But until then, stay safe everybody, and remember to take a break whenever you need it.

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