Weigh Your Car With Paper

September 30, 2020 by Brian McEvoy 23 Comments

Sometimes a problem is more important than its solution. Humans love to solve mysteries and answer questions, but the most rewarding issues are the ones we find ourselves. Take [Surjan Singh], who wanted to see if he could calculate the weight of his Saab 96. Funny enough, he doesn’t have an automobile scale in his garage, so he had to concoct a workaround method. His solution is to multiply the pressure in his tires with their contact patch. Read on before you decide this is an imperfect idea.

He measures his tires with a quality gauge for the highest accuracy and pressurizes them equally. Our favorite part is how he measures the contact patch by sliding a couple of paper pieces from the sides until they stop and then measures the distance between them. He quickly realizes that the treads didn’t contact the floor evenly, so he measures them to get a better idea of the true contact area. Once he is satisfied, he performs his algebra and records the results, then drives to some public scales and has to pay for a weigh. His calculations are close, but he admits this could be an imprecise method due to an n-of-one, and that he didn’t account for the stiffness of the tire walls.

This was a fun thought experiment with real-world verification. If you’re one of those people who treats brainstorming like an Olympic sport, then you may enjoy the gedankenexperiment that is fractals.

E-Textile Tools Get The Multimeter Hookup

September 19, 2020 by Kristina Panos No comments

[Irene Posch] has done some incredible work with knitted, crocheted, and fabric circuits — check out the crocheted ALUs and embroidered computer for starters. Now, it seems [Irene] is building up a how-to catalog of e-textile tools that can be easily connected to a multimeter.

So far, this toolbox includes a seam ripper and a crochet hook. The concept is similar for both — print out a handle and connect the tool to a banana jack that can then be connected to a multimeter. The crochet hook is simple: just print out the handle, jam the hook in one end, and stick a mini banana jack in the other end. They’re designed to butt up against each other and make a connection without wires.

Building the ripper takes a bit more effort. There’s another printed handle involved, but you must first free the seam ripper from its stock plastic handle and solder a wire to it. Then twist the other end of the wire around a banana jack and and put that in the other end of the handle.

It’s great to see a little bit insight into the troubleshooting tools of e-textiles, especially because they are all-around fiddly. It all starts with a circuit, so why not do your prototyping with a thread-friendly breadboard?

Putting The Firmware In Your Firmware

September 15, 2020 by Kerry Scharfglass 12 Comments

Performing over-the-air updates of devices in the field can be a tricky business. Reliability and recovery is of course key, but even getting the right bits to the right storage sectors can be a challenge. Recently I’ve been working on a project which called for the design of a new pathway to update some small microcontrollers which were decidedly inconvenient.

There are many pieces to a project like this; a bootloader to perform the actual updating, a robust communication protocol, recovery pathways, a file transfer mechanism, and more. What made these micros particularly inconvenient was that they weren’t network-connected themselves, but required a hop through another intermediate controller, which itself was also not connected to the network. Predictably, the otherwise simple “file transfer” step quickly ballooned out into a complex onion of tasks to complete before the rest of the project could continue. As they say, it’s micros all the way down.

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Weather Warnings And Dust Detection From This Meteorological Marvel

September 14, 2020 by Brian McEvoy 4 Comments

We love getting our weather in a flurry of different methods, but have you tried building your own sensor suite to harvest the data for you? [Giovanni ‘CyB3rn0id’ Bernardo] needed to monitor isolated locations outside the reach of WiFi. His ray of hope is an ESP32 controller coupled with a LoRa module to beam data to a remote station that can access the cloud.

In addition to radios, he poured a deluge of sensors into the base station to read the temperature, barometric pressure, humidity, and fine dust. Why monitor dust as part of weather data collection? Particulate matter has a huge effect on air quality, something of great interest during a respiratory pandemic. For those readers near wildfires, quantifying your air quality (both indoors and out) is certainly of interest. [Giovanni] is using an SDS011 air quality sensor and has a long writeup just on this part. It uses a fan to move air past a laser-based sensing mechanism.

At the base station, live readings are shown on an OLED screen, but you can also connect to the ESP32 through your phone like a hotspot. If you keep a memory card installed, it will cache the readings in a perpetually-updated CSV file. In regular operation, the LoRa module overcasts the telemetry to its sister unit that acts as a Wifi/LoRa bridge so anyone can view gauges and graphs in real-time on ThingSpeak.

We want to shower [CyB3rn0id] with praise for seeing the ~~cirrus~~ serious impact of harmful dust and making something that can alert people. We don’t want to rain on anyone’s parade, but sometimes it is better to stay inside.

Infinity Mirror At Warp Speed

September 11, 2020 by Brian McEvoy 10 Comments

Inventing often combines more than one old ideas into a new one. Even when the fused things are similar, the result can be more valuable than the sum of its parts. Unlike those analog watches with a digital clock below the face, when [Mojoptix] combined the re-reflecting properties of an infinity mirror with the image twisting qualities of a funhouse mirror, we get more than just a pair of mirrors. The resulting images look like a lot of fun. Warping one surface of two parallel mirrors doesn’t just alter the result a bit, because the planes feed off each other’s view, the final product is an exponentially skewed show.

Our host mounts a 3D printed ring with an hubward-facing strip of LEDs to an ordinary glass mirror. Over that, he designs four mated plates that hold semi-reflective film sheets in different shapes. The first is a hyperbolic paraboloid, but it’s probably easier to think of it as shaped like a Pringles chip (crisp). Once the light is applied, it looks like a bowtie made by a deranged god or the start of an infinite rabbit hole of light and reflection. To further the madness, he hits us with four shapes at once, so we hope you’ll take a moment to enjoy the video below.

This guy is no stranger to optics, and we’ve reported on a couple of other cool inventions that teach a concept through demonstration. His precision calipers demonstrate the Moiré effect, and his digital sundial capitalizes on parallel light beams.

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40% Keyboard Build Is 100% Open Source

September 7, 2020 by Kristina Panos 21 Comments

[Blake]’s interest in building keyboards happened naturally enough — he was looking for a new project to work on and fell into the treasure chest that is the mechanical keyboard community. It sounds like he hasn’t built anything but keyboards since then, and we can absolutely relate.

This tidy 40% ortholinear is [Blake]’s third build, not including macro keebs. It’s based on an open source case and plate from Thingiverse, and uses an Arduino Pro Micro running the popular QMK firmware to read input from 47 Gateron blues and a rotary encoder.

We particularly like the double rainbow ribbon cable wiring method [Blake] used to connect each row and column to the controller. It looks beautiful, yes, but it’s also a great way to maintain sanity while programming and troubleshooting.

Keyboard builds can look daunting, even at 40% of standard size. But as [Blake] discovered, there are some really good guides out there with fantastic tips for hand-wiring in small spaces. And now there is another well-written guide with clear pictures to point to.

Looking to split from the standard rectangle form factor but don’t know what to go with? Divine your next clacker with this split keyboard finder.

Thanks for the tip, [jrdsgl]!