Parts of the automated soil moisture monitoring station

Solar Stevenson Screen For Smart Sprinkler

April 11, 2021 by Bob Baddeley 1 Comment

It’s not infrequent that we see the combination of moisture sensors and water pumps to automate plant maintenance. Each one has a unique take on the idea, though, and solves problems in ways that could be useful for other applications as well. [Emiliano Valencia] approached the project with a few notable technologies worth gleaning, and did a nice writeup of his “Autonomous Solar Powered Irrigation Monitoring Station” (named Steve Waters as less of a mouthful).

Of particular interest was [Emiliano]’s solution for 3D printing a threaded rod; lay it flat and shave off the top and bottom. You didn’t need the whole thread anyway, did you? Despite the relatively limited number of GPIO pins on the ESP8266, the station has three analog sensors via an ADS1115 ADC to I2C, a BME280 for temperature, pressure, and humidity (also on the I2C bus), and two MOSFETs for controlling valves. For power, a solar cell on top of the enclosure charges an 18650 cell. Communication over wireless goes to Thingspeak, where a nice dashboard displays everything you could want. The whole idea of the Stevenson Screen is clever as well, and while this one is 3D printed, it seems any kind of stacking container could be modified to serve the same purpose and achieve any size by stacking more units. We’re skeptical about bugs getting in the electronics, though.

We recently saw an ESP32-based capacitive moisture sensor on a single PCB sending via MQTT, and we’ve seen [Emiliano] produce other high quality content etching PCBs with a vinyl cutter.

Dynamic Build Platforms For 3D Printers Remove Supports And Save Material

April 10, 2021 by Bob Baddeley 31 Comments

We’re all too familiar with the 3D printing post-processing step of removing supports, and lamenting the waste of plastic on yet another dwindling reel of filament. When the material is expensive NinjaFlex or exotic bio-printers, printing support is downright painful. A group at USC has come up with a novel way of significantly reducing the amount of material that’s 3D printed by raising portions of the bed over time, and it makes us wonder why a simpler version isn’t done regularly.

In the USC version, the bed has a bunch of square flat metal pieces, with a metal tube underneath each. The length of the tube determines the eventual height of that square. Before the print is made, the bed is prepared by inserting the appropriate length tubes in the correct squares. Then, during the print, a single motor pushes a platform up, and based on the height of the pin, that portion of the bed raises appropriately, then stops at the right height.

This is a significant savings over having a matrix of linear motors or servos to control each square, at the cost of having to prepare the pins for each print.

But it has us wondering; since CURA and other slicing software have the ability to pause at height, what if the slicing software could allow for the placement of spacer blocks of a known size? The user would have a variety of reusable spacer blocks, and position them in the software, and the slicer would build the support material starting on top of the block. It could print a rectangle on the base layer to aid in proper placement of the blocks during printing, and pause at the correct heights to let the user insert the blocks. At the end of the print a lot less support material has been used.

For situations where you want to leave your print to run unattended, or if the cost of the material is low enough that it doesn’t justify the effort, then maybe this isn’t worth it. Another problem might be heating that platform, though since only support material will be printed on it, some curling won’t matter much. What do you think?

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It Costs WHAT?! A Sounding Into Hearing Aids

February 1, 2021 by Bob Baddeley 153 Comments

We are accustomed to medical devices being expensive, but sometimes the costs seem to far exceed reasonable expectations. At its most simplistic, a hearing aid should just be a battery, microphone, amplifier, and speaker, all wrapped in an enclosure, right? These kinds of parts can be had for a few dimes, so why do modern hearing aids cost thousands of dollars, and why can’t they seem to go down in price?

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The Cost Of Moving Atoms In Space; Unpacking The Dubious Claims Of A $10 Quintillion Space Asteroid

November 23, 2020 by Bob Baddeley 42 Comments

The rest of the media were reporting on an asteroid named 16 Psyche last month worth $10 quintillion. Oddly enough they reported in July 2019 and again in February 2018 that the same asteroid was worth $700 quintillion, so it seems the space rock market is similar to cryptocurrency in its wild speculation. Those numbers are ridiculous, but it had us thinking about the economies of space transportation, and what atoms are worth based on where they are. Let’s break down how gravity wells, distance, and arbitrage work to figure out how much of this $10-$700 quintillion we can leverage for ourselves.

The value assigned to everything has to do with where a thing is, AND how much someone needs that thing to be somewhere else. If they need it in a different place, someone must pay for the transportation of it.

In international (and interplanetary) trade, this is where Incoterms come in. These are the terms used to describe who pays for and has responsibility for the goods between where they are and where they need to be. In this case, all those materials are sitting on an asteroid, and someone has to pay for all the transport and insurance and duties. Note that on the asteroid these materials need to be mined and refined as well; they’re not just sitting in a box on some space dock. On the other end of the spectrum, order something from Amazon and it’s Amazon that takes care of everything until it’s dropped on your doorstep. The buyer is paying for shipping either way; it’s just a matter of whether that cost is built into the price or handled separately. Another important term is arbitrage, which is the practice of taking a thing from one market and selling it in a different market at a higher price. In this case the two markets are Earth and space.

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Bespoke Storage Technologies: The Alphabet Soup Found In Modern Hard Drives And Beyond

November 4, 2020 by Bob Baddeley 70 Comments

It seems like just yesterday (maybe for some of you it was) we were installing Windows 3.1 off floppy drives onto a 256 MB hard drive, but hard drives have since gotten a lot bigger and a lot more complicated, and there are a lot more options than spinning platters.

The explosion of storage options is the result of addressing a variety of niches of use. The typical torrenter downloads a file, which is written once but read many times. For some people a drive is used as a backup that’s stored elsewhere and left unpowered. For others it is a server frequently reading and writing data like logs or swap files. In all cases it’s physics that sets the limits of what storage media can do; if you choose wisely for your use case you’ll get the bet performance.

The jargon in this realm is daunting: superparamagnetic limit, LMR, PMR, CMR, SMR, HAMR, MAMR, EAMR, XAMR, and QLC to name the most common. Let’s take a look at how we got here, and how the past and present of persistent storage have expanded what the word hard drive actually means and what is found under the hood.

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Dealing With A Hacked Brain; Let’s Talk About Depression

August 26, 2020 by Bob Baddeley 100 Comments

This post is different from normal Hackaday fare. I don’t want to presume anything about you, but I’m pretty sure the story I’m about to share resonates with at least some of you.

I’ve been having a tough time, exacerbated by this age of social distancing. This all crept up on me at first, but as I began to look back on my behavior and moods, I began noticing patterns that I hadn’t noticed before. This is certainly a relevant issue in this community, so let’s talk about mental health, beginning with my own journey.

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Professional Ventilator Design Open Sourced Today By Medtronic

March 30, 2020 by Bob Baddeley 116 Comments

Medical device company Medtronic released designs for one of their ventilators to open source for use in the COVID-19 pandemic. This is a laudable action, and there is plenty to glean from the specs (notable is that the planned release is incomplete as of this writing, so more info is on the way). Some initial reactions: medical devices are complicated, requirements specifications are enormous, the bill of materials (BOM) is gigantic, and component sourcing, supply chain, assembly, and testing are just as vital as the design itself.

The pessimist in me says that this design was open sourced for two reasons; to capitalize on an opportunity to get some good press, and to flex in front of the DIY community and convince them that the big boys should be the ones solving the ventilator shortage. The likelihood of anyone actually taking these specs and building it as designed are essentially zero for a variety of reasons, but let’s assume their intent is to give a good starting point for newer changes. The optimist in me says that after what happened to California over the weekend with 170 ventilators arriving broken, it might be nice to have open designs to aid in repair of existing non-functioning ventilators.

The design details released today are for their PB560 model, which was originally launched in 2010 by a company called Covidien, before it merged with Medtronic, so we’re already starting with a device design that’s a decade old. But it’s also a design that has proven itself through widespread use, and this data dump gives us a great look at what actually goes into one of these machines. Let’s take a look.

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