Small, Quiet Air Compressor Puts 3D-Printed Parts To Best Use

April 11, 2024 by Dan Maloney 14 Comments

When the only tool you’ve got is a hammer, every problem starts to look like a nail. Similarly, while a 3D printer is a fantastic tool to have, it can make you think it’s possible to build all the things with printed parts. Knowing when to print ’em and when to machine ’em is important, a lesson that [Diffraction Limited] has taken to heart with this semi-printed silent air compressor.

The key to this compressor’s quiet operation is a combination of its small overall size. its relatively low output, and its strategic use of plastic components, which tend to dampen vibrations. The body of the compressor and the piston arms are the largest 3D-printed parts; the design calls for keeping printed parts in compression for longer life, while the parts of the load path in tension travel through fasteners and other non-printed parts. The piston design is interesting — rather than being attached to connecting rods via wrist pins, the machined Delrin pistons are solidly attached to the piston arms. This means they have to swivel within the cylinders, which are made from short pieces of metal tubing, with piston seals designed to move up and down in grooves on the pistons to allow air to move past them. The valve bodies atop each cylinder are salvaged from another compressor.

When powered by a NEMA23-frame BLDC motor via a belt drive, the compressor is remarkably quiet; not quite silent perhaps, but still impressively smooth, and capable of 150 PSI at low speeds. And as a bonus, the split crankcase makes it easy to open up and service, or just show off how it works. We’ve seen a variety of 3D-printed compressors, from screw-type to Wankel, but this one really takes the prize for fit and finish. Continue reading “Small, Quiet Air Compressor Puts 3D-Printed Parts To Best Use” →

Custom Fume Hood For Safe Electroless Plating

October 22, 2023 by Bryan Cockfield 10 Comments

There are plenty of chemical processes that happen commonly around the house that, if we’re really following safety protocols to the letter, should be done in a fume hood. Most of us will have had that experience with soldering various electronics, especially if we’re not exactly sure where the solder came from or how old it is. For [John]’s electroless plating process, though, he definitely can’t straddle that line and went about building a fume hood to vent some of the more harmful gasses out of a window.

This fume hood is pretty straightforward and doesn’t have a few of the bells and whistles found in commercial offerings, but this process doesn’t really require things like scrubbing or filtering the exhaust air so he opted to omit these pricier and more elaborate options. What it does have, though, is an adjustable-height sash, a small form factor that allows it to easily move around his shop, and a waterproof, spill-collecting area in the bottom. The enclosure is built with plywood, allowing for openings for an air inlet, the exhaust ducting, and a cable pass-through, and then finished with a heavy-duty paint. He also included built-in lighting and when complete, looks indistinguishable from something we might buy from a lab equipment supplier.

While [John] does admit that the exhaust fan isn’t anything special and might need to be replaced more often than if he had gone with one that was corrosion-resistant, he’s decided that the cost of this maintenance doesn’t outweigh the cost of a specialized fan. He also notes it’s not fire- or bomb-proof, but nothing he’s doing is prone to thermal anomalies of that sort. For fume hoods of all sorts, we might also recommend adding some automation to them so they are used any time they’re needed.

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Better Air Quality Sensing With CO2

November 21, 2022 by Bryan Cockfield 19 Comments

Measuring air quality, as anyone who has tried to tackle this problem can attest, is not as straightforward as it might seem. Even once the nebulous term “quality” is defined, most sensors use something as a proxy for overall air health. One common method is to use volatile organic compounds (VOCs) as this proxy but as [Larry Bank] found out, using these inside a home with a functional kitchen leads to a lot of inaccurate readings. In the search for a more reliable sensor, he built this project which uses CO2 to help gauge air quality.

Most of the reason that CO2 sensors aren’t used as air quality sensors is cost. They are much more expensive than VOC sensors, but [Larry] recently found one that was more affordable and decided to build this project around it. The prototype used an Arduino communicating over I2C to the sensor and an OLED screen, which he eventually put in a 3D printed case to carry around to sample CO2 concentration in various real-world locations. The final project uses a clever way of interfacing with the e-paper display that we featured earlier.

While CO2 concentration doesn’t tell the full story of air quality in a specific place, it does play a major role. [Larry] found concentrations as high as 3000 ppm in his home, which can cause a drop in cognitive function. He’s made some lifestyle changes as a result which he reports has had a beneficial impact. For human-occupied indoor spaces, CO2 can easily be the main contributor to poor air quality, and we’ve seen at least one other project to address this concern directly.

Ceiling Fan Adds CO2 Sensor

October 7, 2022 by Bryan Cockfield 18 Comments

Ceiling fans seem to be an oft-misunderstood or overlooked household appliance. As such, they seem to have missed a lot of the IoT wave. Sure, you can get smart controllers for them to plug into your home automation system of choice, but these mostly rely on temperature sensors, simple timers, or voice commands. There’s a lot more to a ceiling fan than maintaining a comfortable temperature, as [EJ] demonstrates with this smarter ceiling fan build.

A big part of the job of a ceiling fan is to improve air circulation, which can help a room from feeling “stuffy”. This feeling is usually caused by excess CO2 as a result of respiration in an area where the air is not moving enough to exhaust this gas. Not only does [EJ]’s controller make use of a temperature monitor for controlling the fan automatically, but there is also a CO2 sensor integrated to improve this aspect of air quality when needed.

The entire build is based on a Raspberry Pi Zero, and nothing needed to be changed about the ceiling fan itself for this added functionality because it already included a radio-based remote control. With some monitoring of the signals produced by the remote, the Raspberry Pi was programmed to mimic these commands when the surrounding sensors captured a condition where [EJ] would want the fan on. There’s also a manual control button as well, so the fan control is not entirely in the hands of the computer.

For a little more detailed information about this build, there’s a separate project page which details a lot of the information about the RF waveform capturing and recreation. And, if you want to take your fan to the next level, take a look at this one which focuses on building a smartphone app to control the fan instead.

Renewable Hydrogen Sucked From Thinish Air

September 11, 2022 by Dave Rowntree 26 Comments

Stored hydrogen is often touted as the ultimate green energy solution, provided the hydrogen is produced from genuinely green power sources. But there are technical problems to be overcome before your average house will be heated with pumped or tank-stored hydrogen. One problem is that the locations that have lots of scope for renewable energy, don’t always have access to plenty of pure water, and for electrolysis you do need both. A team from Melbourne University have come up with a interesting way to produce hydrogen by electrolysis directly from the air.

Redder areas have more water risk and renewable potential

By utilising a novel electrolysis cell with a hygroscopic electrolyte, the so-called direct air electrolysis (DAE) can operate with humidity as low as 4% relative, so perfectly fine even in the most arid areas, after all there may not be clouds but the air still holds a bit of water. This is particularly relevant to regions of the world, such as deserts, where there is simultaneously a high degree of water risk, and plenty of solar potential. Direct electrolysis of saline extracted at coastal areas is one option, but dealing with the liberated chlorine is a big problem.

The new prototype is very simple in construction, with a sponge of melamine or a sintered glass foam soaked in a compatible electrolyte. Potassium Hydroxide (alkaline) was tried as was Potassium Acetate (base) and Sulphuric Acid, but the latter degraded the host material in a short time. Who would have imagined? Anyway, with electrolysis cell design, a key problem is ensuring the separate gasses stay separate, and in this case, are also separate from the air. This was neatly ensured by arranging the electrolyte sponge fully covered both electrodes, so as the hygroscopic material extracted water from the air, the micro-channels in the structure filled up with liquid, with it touching both ends of the cell, forming the circuit and allowing the electrolysis to proceed.

Hydrogen, being very light, would rise upward through holes in the cathode, to be collected and stored. Oxygen simply passed back into the air, after passing though the liquid reservoir at the base. Super simple, and from reading the paper, quite effective too.

You can kind of imagine a future built around this now, where you’re driving your hydrogen fuel cell powered dune buggy around the Sahara one weekend, and you stop at a solar-powered hydrogen fuel station for a top up and a pasty. Ok, possibly not that last bit.

The promised hydrogen economy may be inching closer. We covered using aluminium nanoparticles to rip hydrogen out of water. But once you have the gas, you need to store and handle it. Toyota might have a plan for that. Then perhaps handling gas directly at all isn’t a great idea, and maybe the future is paste?

Thanks to [MmmDee] for the tip!

The Benefits Of Displacement Ventilation

July 7, 2022 by Lewin Day 27 Comments

The world has been shaken to its core by a respiratory virus pandemic. Humanity has been raiding the toolbox for every possible weapon in the fight, whether that be masks, vaccinations, or advanced antiviral treatments.

As far as medicine has come in tackling COVID-19 in the past two years, the ultimate solution would be to cut the number of people exposed to the pathogen in the first place. Improving our ventilation methods may just be a great way to cut down on the spread. After all, it’s what they did in the wake of the Spanish Flu.

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Compact Sensor Keeps You Safe By Watching CO2 Levels

August 24, 2021 by Dan Maloney 21 Comments

Remember when work meetings were just a bunch of people filling up a small, poorly ventilated room with their exhaled breath? Back in the good old days, all you had to worry about was being lulled to sleep by a combination of the endless slide deck and the accumulation of carbon dioxide. Now? Well, the stakes may just be a little bit higher.

In either situation, knowing the CO₂ level in a room could be a handy data point, which is where a portable CO₂ sensor like this one could be useful. Or at least that’s [KaRMaN]’s justification for SYPHCOM, the “simple yet powerful handheld carbon dioxide meter.” The guts of the sensor are pretty much what you’d expect — an Arduino Pro Micro, a SenseAir S8 CO₂ sensor board, and the necessary battery and charging circuits. But the build does break the mold in a couple of interesting places. One is in the choice of display — a 1980s-era LED matrix display. The HDSP2000 looks like it belongs in a nice bench meter, and is surprisingly legible without a filter. It looks like it flickers a bit in the video below, but chances are that’s just a camera artifact.

The other nice part of this build is the obvious care [KaRMaN] put into making it as small as possible. The layout of boards and components is very clever, making this a solid, compact package, even without an enclosure. We’ve seen CO₂ sensors with more features, but for a quick check on air quality, SYPHCOM looks like a great tool.

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