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Hackaday Links: September 11, 2022

Good news out of Mars from the little lunchbox that could — in the seven times that MOXIE has run since it arrived in February 2021, it has reached its target production of six grams of oxygen per hour, which is in line with the output of a modest tree here on Earth. The research team which includes MOXIE engineers report that although the solid oxide electrolysis machine has shown it can produce oxygen at almost any time or day of the Martian scale, they have not shown what MOXIE can do at dawn or dusk, when the temperature changes are substantial, but they say they have ‘an ace up (their) sleeve’ that will let them do that. We can’t wait to see what they mean.

In other, somewhat funnier space news — early last Sunday morning, the ESA’s Solar Orbiter was cruising by Venus as part of a gravity-assist maneuver to get the Orbiter closer to the Sun. Two days before the Orbiter was to reach its closest point to the spacious star, it spat a coronal mass ejection in the general direction of both Venus and the Orbiter (dibs on that band name), as if to say ‘boo’. Fortunately, the spacecraft is designed to withstand such slights, but the same cannot be said for Venus — these events have their way with Venus’ atmosphere, depleting it of gasses.

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Hackaday Prize 2022: A Sun-Chasing Robot

There’s plenty of power to be had from the sun, but you need to be out of the shade to receive it. [Dennis] built a robot by the name of Sun Chaser that has the smarts to go where the sun is shining.

Sun Chaser is essentially a robotic solar panel, tasked with filling up its batteries as much as possible. It can then be used as a power supply for campsites or other remote areas, and used to charge devices as required.

A Raspberry Pi runs the show, paired with a Squid motor controller to run the drive system. Sun Chaser has a motorized solar panel onboard which can track the sun for maximum output, with the aid of six photoresistors to guide the positioning. A camera is used to image the area around Sun Chaser, too, and processing is used to identify sunny regions which will provide the most energy.

Even outside of its useful applications, the idea of having a robot that can run around and keep itself juiced up is a fun one. Solar power gives a robot a greater sense of autonomy, after all. This author has experimented in this field to great enjoyment, too. Video after the break.

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Hackaday Prize 2022: Solar Power Through Pyrolysis

We’re all familiar with solar cells, be they photovoltaic, or for heating water. But they are only the more common ways of converting the sun’s energey into usable power, and to the extended list there is now an addition courtesy of [Dennis]. He’s using the sun to drive the pyrolysis of biomass waste, releasing hydrogen fuel.

For those who aren’t familiar with the chemistry, pyrolysis refers to chemical reactions triggered by heat. In this case, when organic biomass is heated in the absence of oxygen it breaks down and releases the gaseous products of that breakdown as well as a mass of carbon. The idea behind this pyrolysis cell is that a Fresnel lens will focus the sun on a reaction chamber, providing the required heat for the reaction to occur. A test with a magnifier and a test tube proves that there’s something in it.

Of course, sharp-eyed readers will notice that this isn’t quite in the same vein as other cells which convert the Sun’s energy into a usable form, in that while it provides an input of energy for the pyrolysis the chemical energy in the resulting gas comes mostly from the original biomass. There is a silver lining to the prospect of burning gas though, in that the left-over carbon can be incorporated into the soil as biochar, an effective carbon sink.

We’ve seen a project pursuing a similar chemistry before, though not using solar energy to do it.

Dead Solar Panels Are The Hottest New Recyclables

When it comes to renewable energy, there are many great sources. Whether it’s solar, wind, or something else, though, we need a lot of it. Factories around the globe are rising to the challenge to provide what we need.

We can build plenty of new solar panels, of course, but we need to think about what happens when they reach end of life. As it turns out, with so much solar now out in the field, a major new recycling industry may be just around the corner.

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2022 Hackaday Prize: ArmaLamp Provides Light, No Matter What

Instant access to electric light is a luxury that most of us take for granted, but in times of crisis, the power is often the first thing to go. So whether you’re worried about a natural disaster or the outbreak of war, a reliable source of light is a must-have in your emergency kit. Creator [bobricius] calls his is ArmaLamp the “Armageddon resistant night lamp”, and while we’re not eager to test that particular claim, it certainly looks robust enough to get you through some tough times.

The basic idea behind the ArmaLamp is to make a light source so simple that, outside of being physically destroyed, it can’t fail. That means deleting the mechanical power switch and designing the circuit so the LED light will kick on automatically in the dark. Rather than using a traditional rechargeable battery, the solar powered ArmaLamp stores its charge in a 10 farad supercapacitor that can be charged and depleted daily without having to worry about long-term degradation.

Charging the ArmaLamp with a simple solar cell is clearly out of the question as it would represent not just a single point of failure, but a particularly fragile one at that. Instead, [bobricius] is using an array of six BPW34 photodiodes that come in a hard plastic package. Combined with an efficient driver circuit that can run the LED even when the supercap is down to 0.3 V, leaving the ArmaLamp outside during the day should provide you with four hours of ultra-reliable light every night.

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A small PCB with an OLED screen showing a Dinosaur Game

Hackaday Prize 2022: RunTinyRun Is A Fully Solar-Powered, Portable Dinosaur Game

Fully solar-powered handheld gadgets have so far mostly been limited to ultra-low power devices like clocks, thermometers and calculators. Anything more complicated than that will generally have a battery and some means to charge it. An entirely solar-powered video game console is surely out of reach. Or is it? As [ridoluc] shows, such a device is actually possible: the RunTinyRun gets all its power directly from the Sun.

To be fair, it’s not really a full-fledged game console. In fact it doesn’t even come close to the original Game Boy. But RunTinyRun is a portable video game with an OLED display that’s completely powered by a solar panel strapped to its back. It will run indefinitely if you’re playing outside on a sunny day, and if not, letting it charge for a minute or two should enable thirty seconds of play time.

The game it runs is a clone of Google’s Dinosaur Game, where you time your button presses to make a T-Rex jump over cacti. As you might expect, the game runs on an extremely minimalist hardware platform: the main CPU is an ATtiny10 six-pin micro with just 1 kB of flash. The game is entirely written in hand-crafted assembly, and takes up a mere 780 bytes. A 0.1 farad supercap powers the whole system, and is charged by a 25 x 30 mm2 solar cell through a boost converter.

RunTinyRun is a beautiful example of systems design within strict constraints on power, code size and board area. If you’re looking for a more capable, though slightly less elegant portable gaming console, have a look at this solar-powered Game Boy.
A Dinosaur Game implementation running on a breadboard setup

Hackaday Prize 2022: Glass Tube Solar Thermionic Converters

Typically, if you want to convert solar energy into electrical energy, you use either photovoltaic (PV) cells, or you use the sunlight to create steam to turn a turbine. Both of these methods are well-established and used regularly in both small- and grid-scale applications. However, [Nick Poole] wanted to investigate an alternative method, using thermionic converters for solar power generation.

[Nick] has been gearing up to produce various styles of vacuum tubes, and noted that the thermionic effect that makes them work could also be used to generate electricity. They are highly inefficient and produce far less power than a photovoltaic solar cell, meaning they’re not in common use. However, as [Nick] notes, unlike PV cells etched in silicon, a thermionic converter can be built with basic glassworking tools, requiring little more than a torch, a vacuum pump, and a spot welder.

Experiments with a large lens to focus sunlight onto a 6V3A diode tube showed promise. [Nick] was able to generate half a volt, albeit at a tiny current, with the design not being optimized for thermionic conversion. Further experiments involved electrically heating a pair of diode tubes, which was able to just barely light an LED at 1.7 V and a current of 7.5 uA. The conversion efficiency was a lowly 0.00012%, around 5 orders of magnitude worse than a typical PV cell.

[Nick]’s hope is that he can produce a tube designed specifically to maximize thermionic conversion for energy generation purposes. It’s likely there is some low-hanging fruit in terms of gains to be made simply by optimizing the design for this purpose, even if the technique can’t compete with other solar generation methods.

In any case, we’re eager to see what [Nick] comes up with! We love to see makers building tubes in their own home workshops.

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