A Portable, Accurate, Low-Cost, Open Source Air Particle Counter

If you live in a city with poor air quality you may be aware that particulates are one of the chief contributors to the problem. Tiny particles of soot from combustion, less than 10μm across, hence commonly referred to as PM10. These are hazardous because they can accumulate deep in the lungs, wherein all kinds of nasties can be caused.

There are commercial sensors available to detect and quantify these particles, but they are neither inexpensive nor open source. [Rundong] tells us about a project that aims to change that situation, the MyPart, which is described as a portable, accurate, low-cost, open source air particle counter. There is a GitHub repository for the project as well as a series of Instructables covering the build in detail. It comes from a team of members of the Hybrid Ecologies Lab at UC Berkeley, USA.

Along the way, they provide a fascinating description of how a particulate sensor works. A laser shines at right angles across a photodiode, and is brought to a focal point above it. Any particulates in the air will scatter light in the direction of the photodiode, which can thus detect them. The design of a successful such sensor requires a completely light-proof chamber carefully built to ensure a laminar flow of air past laser and diode. To that end, their chamber has several layers and is machined rather than 3D-printed for internal smoothness.

We’ve covered quite a few environmental sensors over the years here at Hackaday. An open source volatile organic compound (VOC) detector featured last year for example, or this Raspberry Pi-based  system using a commercial gas sensor.

Fail of the Week: Upcycling Failed 3D Prints

Is it possible to recycle failed 3D prints? As it turns out, it is — as long as your definition of “recycle” is somewhat flexible. After all, the world only needs so many coasters.

To be fair, [Devin]’s experiment is more about the upcycling side of the recycling equation, but it was certainly worth undertaking. 3D printing has hardly been reduced to practice, and anyone who spends any time printing knows that it’s easy to mess up. [Devin]’s process starts when the colorful contents of a bin full of failed prints are crushed with a hammer. Spread out onto a properly prepared (and never to be used again for cookies) baking sheet and cooked in the oven at low heat, the plastic chunks slowly melt into a thin, even sheet.

[Devin]’s goal was to cast them into a usable object, so he tried to make a bowl. He tried reheating discs of the material using an inverted metal bowl as a form but he found that the plastic didn’t soften evenly, resulting in Dali-esque bowls with thin spots and holes. He then flipped the bowl and tried to let the material sag into the form; that worked a little better but it still wasn’t the win he was looking for.

In the end, all [Devin] really ended up with is some objets d’art and a couple of leaky bowls. What else could he have done with the plastic? Would he have been better off vacuum forming the bowls or perhaps even pressure forming them? Or does the upcycling make no sense when you can theoretically make your own filament? Let us know in the comments how you would improve this process.

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Living off the Grid, on Water Power

When you think of living off the grid, you often think of solar power. But if you’ve got a good head, and enough flow, water power can provide a much more consistent flow of electrons. All it requires is a little bit of engineering, epic amounts of manual labor, and some tricks of the trade, and you’ll have your own miniature hydroelectric power plant.

[Homo Ludens], the playful ape, has what looks like a fantastic self-sufficient home/cabin in a beautiful part of Chile. His webpages are a tremendous diary of DIY, but the microhydro plant stands out.

You might expect that building a hydro plant involves a lot of piping, and trenching to lie that pipe in, but the exact extent, documented in many photos, is sobering. At places, the pipe needed to be bent, and [Homo Ludens] built a wire-mesh pipe heater to facilitate the work — with the help of a few friends to weigh the pipe down at either end and create the bend. The self-wound power transformer is also a beauty.

There’s a lot more detail here than we can possibly get into, so go check it out. And if you’re in the mood for more hydro, we’ve recently run a writeup of a less ambitious, but still tidy, project that you should see. Or you could just rip apart an old washing machine.

Thanks [Patrick] for the great tip!

A Modest But Well-Assembled Home Hydropower Setup

We have all opened an electricity bill and had thoughts of saving a bit of money by generating our own power. Most of us never get any further than just thinking about it, but for anyone willing to give it a try we are very fortunate in that we live in a time at which technology has delivered many new components that make it a much more straightforward prospect than it used to be. Electronic inverters, efficient alternators, and electronic battery management systems are all easy to find via the internet, and are thus only a matter of waiting for the courier to arrive.

Pelton Wheel
Pelton Wheel

[Frédéric Waltzing] is lucky enough to have access to a 135 foot (38 metre) head of water that those of us in flatter environments could only dream of. He’s used it to generate his own power using a modestly sized but very effective turbine, and he documented it in a Youtube video which you can see below the break.

He brings the water to his turbine house through a 1.5 inch plastic pipe, in which he maintains a 55PSI closed pressure that drops to 37PSI when the system is running. His Pelton wheel develops 835RPM, from which a small permanent magnet alternator provides 6.3A for his battery management system. An Enerwatt 2KW inverter provides useful power from the system.

This hydroelectric installation might not be very large, but its key is not in its size but that it can run continuously. A continuous free 6.3A charge can store up a lot of energy for those times when you need it.

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Finding A Use For Surplus Filament Spools

If you’re a heavy user of a 3D printer, or a welder, you’ll know the problem of empty spools. You’ve used up all the filament or the welding wire, and you’re left with a substantial plastic spool. It’s got to be useful for something, you think, and thus it’s Too Good To Throw Away. Before you know it you have a huge pile of the things all looking for a use that you know one day you’ll find.

If you follow the example of [Chuck Hellebuyck], you could use them as wheels for a small go-kart (YouTube link). He 3D-printed some hub adapters for the spools to use skate bearings, mounted them of threaded axles to a classic wooden go-kart frame, and set off downhill wearing his stock-car racing helmet.

Of course, [Chuck]’s go-kart is a bit of fun, but it’s probably fair to say that 3D printer spools are not the ideal wheel. Those rims aren’t particularly durable, and with no tires he’s in for a bumpy ride. Perhaps a tire could be found to fit and a tube placed within it, but that would start to sound expensive against those cheap off-the-shelf wheelbarrow items.

But the project does raise the interesting question: what exactly do you do with your empty spools? There have to be some awesome uses for them, so please share yours in the comments. Meanwhile follow Chuck’s go-kart adventures in the video below the break.

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Counting Eggs With A Webcam

You’ll have to dig out your French dictionary (or Google translate) for this one, but it is worth it. [Nicolas Giraud] has been experimenting with ways to use a webcam to detect the number of eggs chickens have laid in a chicken coop. This page documents these experiments using a number of different algorithms to automatically detect the number of eggs and notify the owner. The system is simple, built around a Pi running Debian Jesse Lite and a cheap USB webcam. An LED running off one of the GPIO pins illuminates the eggs, and the camera then captures the image for analysis.

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Hackathon Alert: Clean Tech At TVCoG

At Hackaday, we get notified of a lot of the cool events going on in hackerspaces all around the world. We’d like to keep you informed too, just in case there’s something going on in your neighborhood.

So we’re going to start running a weekly column on Saturdays that groups together all of the upcoming week’s exceptional events and noteworthy gatherings. If your hackerspace has something going on, tell us about your event on or around the preceding Wednesday. We’ll see your space in on Hackaday!
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