jellyandmarshmallows windTunnel close-up

Perfecting Paper Planes Peering Past Perspex Portals

This wind tunnel is a pile of junk and we love it! When making science and engineering accessible to kids, it really helps to show that it doesn’t require a fancy research lab. [Jelly & Marshmallows] show kids that it takes little more than cardboard, duct tape, and dumpster-diving to up your paper airplane game to NASA levels of engineering.

[Jelly & Marshmallows] built their wind tunnel for a Maker Faire using the aforementioned cheap and free materials for the straightener, collector, diffuser, and fan sections. We especially love the efficient hack of using stacked ceiling light diffusers rather than hundreds of straws for the straightener.

 

The most time went into the working section, custom-built from plywood frames and acrylic windows. Many 3D printed parts came together to convert a smoke-ring gun to emit smoke trails and LEDs were employed to make those trails a little easier to see. We think the magnetic clips for quick changes of aircraft and their position along a steel ruler were inspired.

The kids attending the Maker Faire (we miss those!) loved the exhibit, having the best time hitting a big green arcade button to spin up the fan. It’s the little things in life. How would you get the kids even more involved with analyzing aerodynamics and make the smoke trails more visible?

 

Thanks for the tip [Rómulo Antão]

The Dynamotor Simplified

[Robert Murray-Smith] doesn’t like the price of inverters to convert DC to AC. That led him to build a dynamotor, or what is sometimes called a motor-generator set. These devices are just DC motors driving a generator. Of course, motors can also be used as generators and [Robert] had a stack of brushless motors in the form of PC fans. A two-fan dynamotor was born.

The brushless motors are attractive because, traditionally, the brushes are what usually fail on a dynamotor. The fan that will act as a generator needs some surgery, but it is simple. He scraped off all the control electronics and connected wires to the coils to form a three-phase generator. There’s no need for the fan blades in that configuration, either. If you were using ordinary motors and a generator, getting shafts concentric would be an important task. With the fans, it is simple to just line up the mounting holes and you get perfect alignment for free.

How does it work? [Robert] has a second video showing the output on a scope. You can see both videos below. The dynamotor makes a good-looking sine wave, probably much better than most reasonable-priced solid state inverters. He didn’t mention how much current he could successfully draw, but it probably isn’t much. You’d also need a transformer to replace a commercial inverter that would put out line voltage, so that would be some more loos in the system. On the other hand, if you wanted AC at a lower voltage, you might just replace all the transformers, if you were building a piece of gear yourself.

We’ve looked at how these things work in some detail. There were common in old tube radios, particularly military ones.

Continue reading “The Dynamotor Simplified”

An Infrared-Activated Solder Fume Extraction Fan

Even the most safety-conscious hackers among us might overlook protective gear when we’re just doing a quick bit of soldering. Honestly, though, eye protection is always a necessity. And those wisps of smoke, which drift so elegantly off the hot part of the iron, really shouldn’t drift directly into our nostrils. This is especially true if soldering you make a daily habit, or if you use lead-based solder.

And so, in defense of his lungs, [Jeremy S Cook] added a battery-powered fume extraction fan to his custom, concrete-based solder squid. Without proper power controls, though, the fan could easily drain its battery while no actual solder activity was occurring. To tackle that problem, he recently upgraded his system with a passive infrared (PIR) sensor to control when the fan turns on and off. The PIR sensor detects motion, enabling the fan only when it sees busy hands in its view, so he no longer needs to muck around with manual controls.

Despite a large increase in functionality, the design is relatively straightforward and uses off-the-shelf components, making it an accessible project for anyone who knows their way around an iron. [Jeremy] also upgraded his power source to a LiPo battery with onboard charger, which keeps the build light, maneuverable, and easy to get close to whatever he’s working on.

Whether you build or buy, a fume extractor will help fight off the famously face-seeking solder smoke on your workbench. Which is a good thing, too, because that smoke carries more than just the alluring aromas of making.

Continue reading “An Infrared-Activated Solder Fume Extraction Fan”

DIY HEPA Fan Clears The Stale Office Air

Although it would be nice, we can’t all work from home. If you have to spend the day in close quarters with other people, you might want more protection than just a mask and sanitizer. Check out [jshanna]’s DIY HEPA filtering fan — it looks like a breeze to build and uses commonly-available parts plus a few 3D-printed pieces to put it all together.

The basis of this attractive and useful office must-have is a muffin fan from Amazon that has an optional variable speed controller. A long threaded rod runs up the center of the HEPA filter, so it attaches kind of like a lampshade. The fan draws up air from underneath and blows it upward through the filter and out into the room. Whenever the HEPA filter gets dirty, just take it out and wash it.

Are you still buying disposable masks? You might save money in the long run by making your own.

Near-Silent Bellows Uses Water Flow And Magnetic Coupling

Fan noise is a contentious issue among the computer community. Some don’t notice it, others rage against it as an annoyance and distraction. Some turn to liquid cooling, while others look to passive solutions to eliminate the scourge. [Matt] of [DIY Perks] may have found a far more oddball solution, however.

The build is essentially a giant bellows, but the manner in which it operates is unlike anything we’ve seen previously. To shift the large pusher plate inside back and forth, [Matt] initially experimented with building his own linear motor out of coils and magnets. After that failed, he began to tinker with a system of moving a magnet back and forth through a tube with water pressure from a pump, which would then drive the pusher plate through magnetic coupling. This looked promising, but reversing the flow proved difficult. After building his own set of water valves to change the flow direction, the bellows began to work slowly, but with limited performance. Realizing the valves weren’t up to scratch, [Matt] rebuilt the system with 10 pumps, set up in two banks of 5. With the pumps hooked up in series, they supplied plenty of pressure to force the bellows back and forth. Reed switches were used to reverse the flow at either end to make the bellows run continuously.

In testing, the bellows compared well with a bank of four large case fans, though at 20 times the size. Suffice to say this is not exactly a compact solution. We look forward to seeing [Matt] do more with the bellows, with his intention being to use it as the primary cooling system for a computer. Of course, if this looks too complex, you could always consider a mineral oil setup instead. Video after the break.

Continue reading “Near-Silent Bellows Uses Water Flow And Magnetic Coupling”

Cheap And Effective Mosquito Trap Looks Like A Disco

Words cannot quite articulate the collective loathing humankind has for mosquitoes, and rightfully so! These parasite peddling, blood sucking little critters are responsible for a great deal of human suffering. Mosquito-borne diseases such as malaria still account for a significant proportion of human mortality, especially in under-developed parts of the world . So it’s no wonder that people try to reduce their numbers; see this latest $40 mosquito trap by [jacobsk]. (Video, embedded below.)

The idea is critically simple, opening up the potential for widespread deployment. The base and body of the trap are made out of three five-gallon buckets with a mini desk fan sandwiched in between, providing suction into the main trap bin. An opening is cut in the top bucket as a point of entry, and an old school incandescent blacklight is mounted in the centre, with just enough IR and UV output to entice these little vermin, who will definitely regret mistaking it for a black-light rave.

[jacobsk] also does a very good job of showing every step of its construction in his videos. Whilst this solution is purposefully low tech, check out this admittedly overcooked way of killing mosquitoes, with a laser turret.

Continue reading “Cheap And Effective Mosquito Trap Looks Like A Disco”

Measuring The Time Is A Breeze With This Air Flow Clock

If you’ve ever had surgery, and you’re over a certain age, chances are good you’re familiar with the dreaded incentive spirometer. It’s a little plastic device with one or more columns, each of which has a plastic ball in it. The idea is to blow into the thing to float the balls, to ensure that your lungs stay in good shape and reduce the chance of pneumonia. This unique air-powered clock reminds us a little of that device, without all the pain.

Like a spirometer, [Nir Tasher]’s clock has three calibrated tubes, each big enough to hold a foam ball loosely. At the bottom of each tube is a blower whose motor is under PWM control. A laser rangefinder sits below each ball and measures its height; the measurement is used by a PID loop to control the speed of each fan and thus the height of each ball. The video below shows that the balls are actually pretty steady, making the clock easy to read. It doesn’t, however, reveal what the clock sounds like; we’re going to go out on a limb here and guess that it’s pretty noisy. Still, we think it’s a fantastic way to keep time, and unique in the extreme.

[Nir]’s Air Flow clock is an early entry in the 2020 Hackaday Prize, the greatest hardware design contest on Earth. Everyone should enter something, or at least check out the cool things people are coming up with. It’s still early in the process, but there are so many neat projects already. What are you waiting for?

Continue reading “Measuring The Time Is A Breeze With This Air Flow Clock”