Misc Hacks

4181 Articles

Rainy Day Fun By Calculating Pi

August 24, 2016 by 14 Comments

If you need a truly random event generator, just wait till your next rainstorm. Whether any given spot on the ground is hit by a drop at a particular time is anyone’s guess, and such randomness is key to this simple rig that estimates the value of pi using raindrop sensors.

You may recall [AlphaPhoenix]’s recent electroshock Settlers of Catan expeditor. The idea with this less shocking build is to estimate the value of pi using the ratio of the area of a square sensor to a circular one. Simple piezo transducers serve as impact sensors that feed an Arduino and count the relative number of raindrops hitting the sensors. In the first video below, we see that as more data accumulates, the Arduino’s estimate of pi eventually converges on the well-known 3.14159 value. The second video has details of the math behind the method, plus a discussion of the real-world problems that cropped up during testing — turns out that waterproofing and grounding were both key to noise-free data from the sensor pads.

In the end, [AlphaPhoenix] isn’t proving anything new, but we like the method here and can see applications for it. What about using such sensors to detect individual popcorn kernels popping to demonstrate the Gaussian distribution? We also can’t help but think of other ways to measure raindrops; how about strain gauges that weigh the rainwater as it accumulates differentially in square and circular containers? Share your ideas in the comments below.

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Compact EPaper Business Card

August 23, 2016 by 39 Comments

Is your business card flashy? Is it useful in a pinch? Do they cost $32 each and come with an ePaper display? No? Well, then feast your eyes on this over-the-top business card with an ePaper display by [Paul Schow]. Looking to keep busy and challenge himself with a low-power circuit in a small package, he set about making a business card that can be updated every couple of months instead of buying a new stack whenever he updated his information.

Having worked with ePaper before, it seemed to be the go-to option for [Schow] in fulfilling the ultra-low power criteria of his project — eventually deciding on a 2″ display. Also looking to execute this project at speed, he designed the board in KiCad over a few hours after cutting it down to simply the power control, the 40-pin connector and a handful of resistors and capacitors. In this case, haste made waste in the shape of the incorrect orientation of the 40-pin connector and a few other mistakes besides. Version 2.0, however, came together as a perfect proof-of-concept, while 3.0 looks sleek and professional.

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Building A DIY Heat Pipe

August 21, 2016 by 75 Comments

Once the secret design tool for aerospace designers, the heat pipe is a common fixture now thanks to the demands of PC CPU cooling. Heat pipes can transfer lots of energy from a hot side to a cold side and is useful when you need to cool something where having a fan near the hot part isn’t feasible for some reason. Unlike active cooling, a heat pipe doesn’t require any external power or pumps, either.

[James Biggar] builds his own heat pipes using copper tubing. You can see a video of one being made, below. There’s not much to it, just a copper pipe with some water in it. However, [James] gets the water boiling to reduce the pressure in the tube before sealing it, which is an interesting trick.

One limitation of his technique is that there is no internal wick. That means the tube can only be installed vertically. If you haven’t looked at heat pipes before, most of them do have a wick. The idea is that some working fluid is in the pipe. You select that fluid so that it boils at or below the temperature you want to handle. The hot vapor rushes to the cool side of the pipe (carrying heat) where you have a large heatsink that may have a fan or active cooling system. The vapor condenses and–in this case–drops back to the bottom of the tube. However, if there is a wick, capillary action will return the fluid to the hot end of the tube.

You might think that using water as the working fluid would limit you to 100°C, but remember, [James’] technique lowers the pressure in the tube. At a lower pressure, the water will boil at a lower temperature.

We’ve seen heat pipes and wine chillers used to cool a PC before. In fact, we’ve even seen them in builds of completely fanless PCs.

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Laser-Cut ArcSin Dress Is Wearable Math

August 19, 2016 by 25 Comments

Using sewing simulation, 3D modeling and laser-cutting [Nancy Yi Liang] makes custom dresses that fit like a glove. Her project documentation walks us through all the steps from the first sketch to the final garment.

After sketching the design on paper, the design process moves into the digital domain, where an accurate 3D model of the wearer is required. [Nancy] created hers with Make Human, a free software that creates to-size avatars of humans from tape-measured parameters. Using the professional garment modeling software MarvelousDesigner (which offers a 30 day trial version), she then created the actual layout. The software allows her to design the cutting patterns, and then also drapes the fabric around the human model in a 3D garment simulation to check the fit. The result are the cutting patterns and a 3D model of the garment.

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Arc Lighter Become Plasma Pyrography Pen

August 18, 2016 by 22 Comments

Wood burning can be quite a striking art form, but who wants to be stuck using an old-fashioned resistive heating element to char wood? You could go with laser engraving, of course, but that seems to take too much of the human touch out of it. So why not try a mini plasma pen and blow torch powered by a fancy cigarette lighter?

Arc lighters are rechargeable electronic lighters that look like a tiny stun-gun, and [NightHawkInLight] has been coming up with some interesting hacks for them. In this case, he extended the electrode leads out and mounted them to a wooden handle. The spark gap is only about 2mm, but the resulting arc is plenty hot enough to char wood with considerable precision. You’ve got to work fast, though, or the high voltage will start finding interesting paths through the char, producing Lichtenberg figures. And if a micro-scale blow torch is a tool you need, [NightHawkInLight] has got that covered too – a small brass tube with a pinched-off nozzle hooked to an aquarium pump provides the pressure for that.

Might there be other applications for this beyond pyrography? Maybe soldering or desoldering? Of non-ESD sensitive components, naturally.

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Solar-powered Weather Station Has The Complete Suite Of Sensors

August 17, 2016 by 15 Comments

There was a time when getting weather conditions was only as timely or as local as the six o’clock news from the nearest big-city TV station. Monitoring the weather now is much more granular thanks to the proliferation of personal weather stations. For the ultimate in personalized weather, though, you might want to build your own solar powered weather station.

It looks like [Brian Masney] went all out in designing his weather station. It supports a full stack of sensors – wind speed and direction, rain, temperature, pressure, and dew point. About the only other parameters not supported (yet) are solar radiation, UV, and soil moisture and temperature. The design looks friendly enough that adding those sensors should be a snap – if fact, the 3D models in his GitHub repo suggest that he’s already working on soil sensors. The wind and rain sensor boom is an off-the-shelf unit from Sparkfun, and the temperature and pressure sensors are housed in a very professional 3D printed screen enclosure. All the sensors talk to a Raspberry Pi living in a (hopefully) waterproof enclosure topped with a solar panel for charging the stations batteries. All in all it’s a comprehensive build; you can check out the conditions at [Brian]’s place on Weather Underground.

Weather stations are popular around these parts, as witnessed by this reverse-engineered sensor suite or even this squirrel-logic based station.

16-channel Sampler Tests Arcade Buttons With Style

August 16, 2016 by 6 Comments

The goal is simple: test a bunch of arcade buttons from different manufacturers to get the one with the best function and feel. The resulting build is anything but simple: this wonderfully over-designed 16-channel WAV sampler and mixer.

For those wondering why [Atarity] would go to this much trouble to test arcade buttons, we suspect an ulterior motive – skip to the 21:14 mark of the long video below to see the real design inspiration. Regardless of the motive, there’s no doubting the care that went into the build – CNC-milled birch case, extremely detailed laser-engraved graphics, and a carbon-fiber back plate covered with suede, because suede. We especially like the detail on the speaker grill: the embroidered fabric and puffed-up look really works with the rest of the design, including the leather hand strap.

It’s not entirely clear from the post what the end goal of the testing is, but we assume it’ll be some sort of MAME build. In which case, [Atarity] might want to check out our recent articles on a tabletop MAME cabinet or this portable MAME rig. But whatever he comes up with, we’re sure the craftsmanship will be there.

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