Gassing Up: Understanding The Liquid Fuel Distribution Network

May 17, 2021 by 40 Comments

When someone talks about “The Grid,” as in “dropping off the grid” or “the grid is down,” we tend to think in terms of the electromagnetic aspects of the infrastructure of modern life. The mind’s eye sees The Grid as the network of wires that moves electricity from power plants to homes and businesses, or the wires, optical cables, and wireless links that form the web of data lines that have stitched the world together informatically.

The Grid isn’t just about power and data, though. A huge portion of the infrastructure of the developed world is devoted to the simple but vital task of moving liquid fuels from one place to another as efficiently and safely as possible. This fuel distribution network, comprised of pipelines, railways, and tanker trucks, is very much part of The Grid, even if it goes largely unseen and unnoticed. At least until something major happens to shift attention to it, like the recent Colonial Pipeline cyberattack.

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Soil Moisture Sensors, How Do They Work?

May 17, 2021 by 19 Comments

In a way, the magic of a soil moisture sensor’s functionality boils down to a simple RC circuit. But of course, in practice there is a bit more to it than that. [rbaron] explains exactly how capacitive soil moisture sensors work simply, clearly, and concisely. He also shows, with a short video, exactly how their output changes in response to their environment, and explains how it informed his own sensor design.

At its heart, a moisture sensor measures how quickly (or slowly) a capacitor charges through a resistor, but in these sensors the capacitor is not a literal component, but is formed by two PCB traces that are near one another. Their capacitance — and therefore their charging rate — changes in response to how much water is around them. By measuring this effect on a probe sunk into dirt, the sensor can therefore indirectly measure the amount of water in the soil.

This ties into his own work on b-parasite: an open-source, all-in-one wireless soil moisture sensor (which was also a runner-up in our Earth Day contest) that broadcasts over BLE and even includes temperature readings. One thing to be mindful of if you are making your own PCBs or ordering them from a fab house is that passing current through metal in a moist environment is a recipe for oxidation, so it’s important not to expose bare traces to wet soil. A good coated PCB should avoid this problem, but one alternative we have seen proposed is to use graphite rods in place of metal.

Actively Balancing A Robot With A Gyroscope

May 17, 2021 by 9 Comments

Self-balancing robots are a common hacker project, but we don’t often see them using spinning gyroscopes to achieve that balance. Robot master [James Bruton] decided to build a robotic platform with active gyroscopic stabilization, starting from a simple proof of concept.

A gyroscope can balance, but cannot actively counteract external forces directly. However, if the gyroscope is tilted around an axis it will exert a force perpendicular to that axis of tilt, known as gyroscopic precession. By tilting the gyroscope with an actuator, and orienting the gyroscope correctly, gyroscopic precession can be used for stabilization. This is known as a control moment gyroscope. [James] demonstrated this with a 3D printed proof of concept, which is used as an IMU to measure the angle of tilt, and use a PID loop to correct the imbalance with a servo actuating the gyroscope.

His second platform used a pair of gyroscopes spinning in opposite directions to compensate for any unintended gyroscopic precession along another axis. A pair of roller skate wheels allow the entire platform to roll along. Due to a slight imbalance in the platform, [James] noticed that the gyroscopes will continue to creep in one direction, until reaching the end-stops and falling over. By adding a second software controller to keep track of how much the gyroscopes have to move to maintain balance, it can continuously calculate and update the balancing point. This prevents the gyroscopes from hitting the end stops.

Control moment gyroscopes are commonly used for attitude control on spacecraft, and to reduce the rolling motion of boats in waves. [James] has plans to combine a control moment gyroscope with the more conventional balancing method, to balance a robot on a single wheel.

We’ve seen a two wheeled RC cars use gyroscopes before, but without the active control part.
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Rodriguez — IV Curve Tracer On The Cheap

May 16, 2021 by 9 Comments

In response to an online discussion on the Electrical Engineering Stack Exchange, [Joseph Eoff] decided to prove his point by slapping together a bare-bones IV curve tracer using an Arduino Nano and a handful of passives. But he continued to tinker with the circuit, seeing just how much improvement was possible out of this simple setup. He squeezes a bit of extra resolution out of the PWM DAC circuit by using the Timer1 library to obtain 1024 instead of 256 steps. For reading voltages, he implements oversampling (and in some cases oversampling again) to eke out a few extra bits of resolution from the 10-bit ADC of the Nano. The whole thing is controlled by a Python / Qt script to generate the desired plots.

While it works and gives him the IV curves, this simplicity comes at a price. It’s slow — [Joseph] reports that it takes several minutes to trace out five different values of base current on a transistor. It was this lack of speed that inspired him to name the project after cartoon character Speedy Gonzales’s cousin,  Slowpoke Rodriguez, AKA “the slowest mouse in all of Mexico”. In addition to being painstakingly slow, the tracer is limited to 5 volts and currents under 5 milliamps.

[Joseph] documents the whole design and build process over on his blog, and has made the source code available on GitHub should you want to try this yourself. We covered another interesting IV curve tracer build on cardboard ten years ago, but that one is much bigger than the Rodriguez.

Magic Pyramids Blink Eternal With The Power Of The Sun

May 16, 2021 by 21 Comments

Without knowing it, we’ve spent years watching [Jasper Sikken] piece together an empire of energy harvesting equipment, and now he’s putting the pieces together into wonderful creations. His recently finished solar harvesting pyramids are mesmerizing objects of geometric perfection we’d love to see glinting in the sun.

These solar harvesting pyramids are well described by their name. Each one contains a PCBA around 30mm on a side with a solar energy harvester built around the dedicated AEM10941 IC, a single solar cell, and a very bright green LED. [Jasper] calculates that the solar cell will charge the super capacitor at 20uA at with just 200 lux of light (a level typical for casual indoor spaces) letting it run indefinitely when placed indoors. Amazingly with the LED blinking for 15ms every 2 seconds it will run for 21 days in complete darkness. And that’s it! This is a software-free piece of hardware which requires no input besides dim light and blinks an LED indefinitely.

Small PCBA, large capacitor

What about that super capacitor? It’s called a Lithium Ion Capacitor (LIC) and is a hybrid between a typical rechargeable lithium battery and an electrolytic capacitor, offering extremely high capacity in a convenient two leg through hole form factor. This one is a whopping 30 Farad at 3.8 V, and we first saw it when [Jasper] won the Hackaday Earth Day contest last month. Check out that link if you want to know more about their uses and how to integrate them.

For more detail about all of the components of the solar pyramid we need only turn to the Hackaday archives. In December 2019 [Tom Nardi] wrote about building a cheap degassing system for making some very familiar looking resin pyramids. And before that [Donald Papp] brought us another familiar piece of the pyramid when he wrote up a different 1″ x 1″ solar harvesting system that [Jasper] designed.

Check out the video after the break to see what one of these gems looks like from all sides. And for many more experiments leading up the final pyramid check out the logs on the Hackaday.io page.

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Hackaday Links: May 16, 2021

May 16, 2021 by 19 Comments

With the successful arrival of China’s first Mars lander and rover this week, and the relatively recent addition of NASA’s Perseverance rover and its little helicopter sidekick Ingenuity, Mars has collected a lot of new hardware lately. But while the new kids on the block are getting all the attention, spare a thought for the reliable old warhorse which has been plying Gale Crater for the better part of a decade now — Curiosity. NASA has been driving the compact-car-sized rover around Mars for a long time now, long enough to rack up some pretty severe damage to its six highly engineered wheels, thanks to the brutal Martian rocks. But if you think Curiosity will get sidelined as its wheels degrade, think again — the rover’s operators have a plan to continue surface operations that includes ripping off its own wheels if necessary. It’s a complex operation that would require positioning the wheel over a suitable rock and twisting with the steering motor to peel off the outer section of the wheel, leaving a rim to drive around on. JPL has already practiced it, but they predict it won’t be necessary until 2034 or so. Now that’s thinking ahead.

With all the upheaval caused by the ongoing and worsening semiconductor shortage, it might seem natural to expect that manufacturers are responding to market forces by building new fabs to ramp up production. And while there seems to be at least some movement in that direction, we stumbled across an article that seems to give the lie to the thought that we can build our way out of the crisis. It’s a sobering assessment, to say the least; the essence of the argument is that 20 years ago or so, foundries thought that everyone would switch to the new 300-mm wafers, leaving manufacturing based on 200-mm silicon wafers behind. But the opposite happened, and demand for chips coming from the older 200-mm wafers, including a lot of the chips used in cars and trucks, skyrocketed. So more fabs were built for the 200-mm wafers, leaving relatively fewer fabs capable of building the chips that the current generation of phones, IoT appliances, and 5G gear demand. Add to all that the fact that it takes a long time and a lot of money to build new fabs, and you’ve got the makings of a crisis that won’t be solved anytime soon.

From not enough components to too many: the Adafruit blog has a short item about XScomponent, an online marketplace for listing your excess inventory of electronic components for sale. If you perhaps ordered a reel of caps when you only needed a dozen, or if the project you thought was a done deal got canceled after all the parts were ordered, this might be just the thing for you. Most items offered appear to have a large minimum quantity requirement, so it’s probably not going to be a place to pick up a few odd parts to finish a build, but it’s still an interesting look at where the market is heading.

Speaking of learning from the marketplace, if you’re curious about what brands and models of hard drives hold up best in the long run, you could do worse than to look over real-world results from a known torturer of hard drives. Cloud storage concern Backblaze has published their analysis of the reliability of the over 175,000 drives they have installed in their data centers, and there’s a ton of data to pick through. The overall reliability of these drives, which are thrashing about almost endlessly, is pretty impressive: the annualized failure rate of the whole fleet is only 0.85%. They’ve also got an interesting comparison of HDDs and SSDs; Backblaze only uses solid-state disks for boot drives and for logging and such, so they don’t get quite the same level of thrash as drives containing customer data. But the annualized failure rate of boot SDDs is much lower than that of HDDs used in the same role. They slice and dice their data in a lot of fun and revealing ways, including by specific brand and model of drive, so check it out if you’re looking to buy soon.

And finally, you know that throbbing feeling you get in your head when you’re having one of those days? Well, it turns out that whether you can feel it or not, you’re having one of those days every day. Using a new technique called “3D Amplified Magnetic Resonance Imaging”, or 3D aMRI, researchers have made cool new videos that show the brain pulsating in time to the blood flowing through it. The motion is exaggerated by the imaging process, which is good because it sure looks like the brain swells enough with each pulse to crack your skull open, a feeling which every migraine sufferer can relate to. This reminds us a bit of those techniques that use special algorithms to detects a person’s heartbeat from a video by looking for the slight but periodic skin changes that occurs as blood rushes into the capillaries. It’s also interesting that when we spied this item, we were sitting with crossed legs, watching our upper leg bounce slightly in time with our pulse.

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Repurpose A Monitor Arm As Microscope Mount

May 16, 2021 by 12 Comments

Being a bit shocked at the prices of articulating arm microscope mounts, not to mention the shipping fees to the UK, [CapTec] realized they looked substantially similar to your typical computer monitor arm mount. Thinking he could adapt a monitor arm for much less money, he fired up FreeCAD and started designing.

[CapTec] is using this to support his Amscope / Eakins camera-equipped trinocular microscope, but notes that the same mechanical bracket / focus rack interface is found on binocular ‘scopes as well. He observes that the mount is no more stable than your desk or lab bench, so keep that in mind.

Ultimately the monitor arm set him back less than $40, and all told he reckons the whole thing was under $55. Based on prices he’s been researching online, this represents a savings of well over $200. In his calculations, the shipping fee comprised quite a hefty percentage of the total cost. We wonder if they are artificially high due to coronavirus — if so, the make / buy price comparison might yield different results in the future.

This type of project is a perfect use-case for a home 3D printer — making your own parts when the normal supply channels are unavailable or overpriced. Are articulating arms that are purpose-built for microscopes significantly different than those designed for big computer monitors? If you know, please comment down below.

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