An E-ink display showing Conway's Game of Life, with a solar cell beneath it

Solar Powered Game Of Life Follows The Sun’s Rhythm

July 28, 2023 by 6 Comments

Conway’s Game of Life is a beautiful example of how complex behavior can emerge from a few very simple rules. But while it uses biological terminology such as “cells”, “alive” and “generation”, the basic game is too simplistic to be a model for any real-world biological process. It’s easy to add features to make it a bit more life-like, however, as [David Hamp-Gonsalves] has done by giving the Conway’s creation something of a circadian rhythm.

The basic idea is that the speed at which [David]’s Game of Life evolves is governed by the amount of ambient light. The game runs off a solar cell that charges a battery, with the battery’s voltage determining how long it takes to advance the game by one generation. The system is therefore highly active in full sunlight, and grinds almost to a complete halt at night.

An ESP32 runs the simulation and outputs the result to a 400 x 300 pixel e-ink display. The display is extremely power-efficient by its very nature; the ESP’s main processor core, on the other hand, is deliberately placed into deep sleep mode most of the time to save as much power as possible. The Ultra Low Power (ULP) co-processor, meanwhile, keeps an eye on the lithium battery’s voltage as it’s slowly being charged by the solar cell. When the voltage reaches 3.3 V, the main CPU wakes up and computes the Game’s new state. In bright sunlight this happens every few seconds, while on an overcast day it could take minutes or even hours.

[David]’s interesting idea of changing Life‘s activity based on the amount of energy available turns the Game into something resembling a cold-blooded animal. We’ve seen a similar approach in a “solar creature” that runs a Life-life simulation on a seven-segment LCD. If it’s speed you care about however, you’re better off implementing Life in an FPGA.

A Deep Dive On Battery Life

July 28, 2023 by 12 Comments

There are all kinds of old wives’ tales surrounding proper battery use floating around in the popular culture. Things like needing to fully discharge a battery every so often, unplugging devices when they’re fully charged, or keeping batteries in the fridge are all examples that have some kernel of truth to them but often are improperly applied. If you really want to know the truth about a specific battery, its behavior, and its features, it helps to dig in and actually take some measurements directly like [Tyler] has done with a vast array of embedded batteries in IoT devices.

[Tyler] is a firmware engineer by trade, so he is deeply familiar with this type of small battery. Battery performance can change dramatically under all kinds of scenarios, most important among them being temperature. But even the same type of battery can behave differently to others that are otherwise identical, which is why it’s important to have metrics for the batteries themselves and be able to measure them to identify behaviors and possible problems. [Tyler] has a system of best practices in place for monitoring battery performance, especially after things like firmware upgrades since small software changes can often have a decent impact on battery performance.

While working with huge fleets of devices, [Tyler] outlines plenty of methods for working with batteries, deploying them, and making sure they’re working well for customers. A lot of it is extremely useful for other engineers looking to develop large-scale products like this but it’s also good knowledge to have for those of us rolling out our own one-off projects that will operate under battery power. After all, not caring for one’s lithium batteries can have disastrous consequences.

Denim Epoxy Table Is A Work Of Art

July 27, 2023 by 34 Comments

Epoxy has become a hugely popular material in the woodworking and furniture worlds. Who doesn’t love glossy, translucent finishes, after all? [Cam] recently spotted some neat combinations of epoxy with denim, and decided to see if he could replicate the technique to create a very unique desk. We’d say he succeeded.

A significant amount of material was involved, with [Cam] claiming he used 1,000 square feet of denim and 20 gallons of epoxy. The denim was sourced as a bulk roll, making it easy to cut to the proper size to make the desk. Liquid Glass epoxy was used for its visual qualities and its hard-wearing nature.

Combining the two materials was a challenging task. The 50 layers of denim had to be squeegeed one at a time to remove excess epoxy, a process made harder by the thickness of the material. Once all laid up, the stack of denim was compressed between sheets of wood, leading to an epoxy spill of monumental proportions.

Regardless, when the final desk was cleaned up and polished, the results were well worth the trouble. It looks like some kind of crazy denim gem thanks to the rich shine and perfect grain. It’s a material we’d like to play with ourselves.

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Exploring Tropical Rainforest Stratification Using Space-Based LiDAR

July 27, 2023 by 11 Comments
GEDI is deployed on the the Japanese Experiment Module – Exposed Facility (JEM-EF). The highlighted box shows the location of GEDI on the JEM-EF.
GEDI is deployed on the the Japanese Experiment Module – Exposed Facility (JEM-EF). The highlighted box shows the location of GEDI on the JEM-EF.

Even though it may seem like we have already explored every single square centimeter of the Earth, there are still many areas that are practically unmapped. These areas include the bottom of the Earth’s oceans, but also the canopy of the planet’s rainforests. Rather having herds of explorers clamber around in the upper reaches of these forests to take measurements, researchers decided to use LiDAR to create a 3D map of these forests (press release).

The resulting GEDI (Global Ecosystem Dynamics Investigation) NASA project includes a triple-laser-based LiDAR system that was launched to the International Space Station in late 2018 by CRS-16 where it has fulfilled its two-year mission which began in March of 2019. Included in the parameters recorded this way are surface topography, canopy height metrics, canopy cover metrics and vertical structure metrics.

Originally, the LiDAR scanner was supposed to be decommissioned by stuffing it into the trunk of a Dragon craft before its deorbit, but after NASA found a way to scoot the scanner over to make way for a DOD payload, the project looks to resume scanning the Earth’s forests next year, where it can safely remain until the ISS is deorbited in 2031. Courtesy of the ISS’s continuous orbiting of the Earth, it’ll enable daily monitoring of its rainforests in particular, which gives us invaluable information about the ecosystems they harbor, as well as whether they’re thriving or not.

Hopefully after its hibernation period the orbital LiDAR scanner will be back in action, as the instrument is subjected to quite severe temperature changes in its storage location. Regardless, putting LiDAR scanners in orbit has to be one of those amazing ideas to help us keep track of such simple things as measuring the height of trees and density of foliage.

A Wigglegram Lens With Variable Aperture

July 27, 2023 by 6 Comments

Wigglegrams are those weird animated pictures you’ve seen that seem to generate a 3D-like effect. [scealux] had built lenses to take such pictures before, but wanted to take things to the next level. Enter the Wigglegram Lens, version 2.

In building a new lens for the Open Sauce ’23 event, [scealux] wanted to get variable aperture working, while also improving focus speed. The lens was also intended for use with a Sony A7R3. Unlike his previous effort, this lens would only work on the full-frame Sony FE mount cameras.

The lens uses a bevy of 3D printed parts, along with plastic lenses salvaged from old disposable cameras. When assembled, it takes three photos simultaneously on one single frame. They can then be reassembled into a Wigglegram by post-processing on a computer. The results are grainy and rough, but yet somehow compelling.

If you want to see [scealux]’s original build for Sony E-mount cameras, we covered it here. Video after the break.

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A Simple One-Handed Solder Feeder

July 27, 2023 by 46 Comments

Soldering can get frustrating when you’re working fast. It often feels like you don’t have enough hands, particularly on jobs where you need to keep feeding solder in a hurry. To solve that issue, [mulcmu] developed a simple one-handed solder feeder.

The solder is fed out of the tip by simply dragging it with the thumb.

The intended use-case is for busy work like soldering long pin headers. The one-handed device allows solder to be continually fed while the other hand uses the soldering iron. It solves a long-running problem for [mulcmu], after their experiments with techniques inspired by TIG welding came to nought.

The design uses a pen-like form factor. A 3D-printed hollow tube has a wire ferrule inserted in the end, which serves as the tip of the device through which solder is fed. The tube has a cutaway, which allows the user to feed solder through using an easy motion of the thumb. The solder itself is fed from a spool in a regular bench top holder. If more slack is required in the solder feed, one simply pins the solder down in the device and tugs to draw more out.

If you find yourself regularly soldering repetitive jobs by hand, this could be a gamechanger for you. Those working in through-hole would be perhaps best served by this device. Meanwhile, if you’ve got nifty tool hacks of your own to share, don’t hesitate to let us know!

 

Magnetic Gearbox, Part 2: Axial Flux Improves Performance

July 27, 2023 by 13 Comments

The number of interesting and innovative mechanisms that 3D printing has enabled always fascinates us, and it’s always a treat when one of them shows up in our feeds. This axial flux magnetic gearbox is a great example of such a mechanism, and one that really makes you think about possible applications.

The principles of [Retsetman]’s gearbox are simple for anyone who has ever played with a couple of magnets to understand, since it relies on that powerful attractive and repulsive force you feel when magnets get close to each other. Unlike his previous radial flux gearbox, which used a pair of magnet-studded cylindrical rotors nested one inside the other, this design has a pair of disc-shaped printed rotors that face each other on aligned shafts. Each rotor has slots for sixteen neodymium magnets, which are glued into the slots in specific arrangements of polarity — every other magnet for the low-speed rotor, and groups of four on the high-speed rotor. Between the two rotors is a fixed flux modulator, a stator with ten ferromagnetic inserts screwed into it.

In operation, which the video below demonstrates nicely, the magnetic flux is coupled between the rotors by the steel inserts in the stator so that when one rotor moves, the other moves at a 4:1 (or 1:4) ratio in the opposite direction. [Retsetman] got the gearbox cranked up to about 8,500 RPM briefly, but found that extended operation at as little as 4,000 RPM invited disaster not due to eddy current heating of the inserts or magnets as one might expect, but from simple frictional heating of the rotor bearings.

Torque tests of the original gearbox were unimpressive, but [Retsetman]’s experiments with both laminated stator inserts and more powerful magnets really boosted the output — up to a 250% improvement! We’d also like to see what effect a Halbach array would have on performance, although we suspect that the proper ratios between the two rotors might be difficult to achieve.

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