Misc Hacks

4177 Articles

Whirling Shutters On This Field Mill Measure Electrostatic Charges At Distance

March 26, 2020 by 34 Comments

Hardly a person hasn’t experienced the sudden, sharp discharge of static electricity, especially on a crisp winter’s day. It usually requires a touch, though, the classic example being a spark from finger to doorknob after scuffing across the carpet. But how would one measure the electrostatic charge of an object without touching it? Something like this field mill, which is capable of measuring electrostatic charge over a range of several meters, will do the trick.

We confess to not having heard of field mills before, and found [Leo Fernekes]’ video documenting his build to be very instructive. Field mills have applications in meteorology, being used to measure the electrostatic state of the atmosphere from the ground. They’ve also played a role in many a scrubbing of rocket launches, to prevent the missile from getting zapped during launch.

[Leo]’s mill works much like the commercial units: a grounded shutter rotates in front of two disc-shaped electrodes, modulating the capacitance of the system relative to the outside world. The two electrodes are fed into a series of transimpedance amplifiers, which boost the AC signal coming from them. A Hall sensor on the shutter allows sampling of the signal to be synchronized to the rotation of the shutter; this not only generates the interrupts needed to sample the sine wave output of the amplifier at its peaks and troughs, but it also measures whether the electrostatic field is positive or negative. Check out the video below for a great explanation and a good looking build with a junk-bin vibe to it.

Meteorological uses aside, we’d love to see this turned toward any of the dozens of Tesla coil builds we’ve seen. From the tiny to the absurd, this field mill should be able to easily measure any Tesla coil’s output with ease.

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[Ben Krasnow] Rolls Old School Camera Out For Photolithography

March 26, 2020 by 14 Comments

In a time when cameras have been reduced to microchips, it’s ironic that the old view camera, with its bellows and black cloth draped over the viewscreen for focusing, endures as an icon for photography. Such technology appears dated and with no application in the modern world, but as [Ben Krasnow] shows us, an old view camera is just the thing when you want to make homemade microchips. (Video, embedded below.)

Granted, the photolithography process [Ben] demonstrates in the video below is quite a bit upstream from the creation of chips. But mastering the process on a larger scale is a step on the way. The idea is to create a high-resolution photograph of a pattern — [Ben] chose both a test pattern and, in a nod to the season, an IRS tax form — that can be used as a mask. The camera he chose is a 4×5 view camera, the kind with lens and film connected by adjustable bellows. He found that modifications were needed to keep the film fixed at the focal plane, so he added a vacuum port to the film pack to suck the film flat. Developing film has always been magical, and watching the latent images appear on the film under the red light of the darkroom really brings us back — we can practically smell the vinegary stop solution.

[Ben] also steps through the rest of the photolithography process — spin coating glass slides with photoresist, making a contact print of the negative under UV light, developing the print, and sputtering it with titanium. It’s a fascinating process, and the fact that [Ben] mentions both garage chip-maker [Sam Zeloof] and [Justin Atkin] from the Thought Emporium means that three of our favorite YouTube mad scientists are collaborating. The possibilities are endless.

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Bee Counter Will Have You Up To Your Nectar In Hive Data

March 22, 2020 by 14 Comments

While we admit that free honey sounds pretty good, beekeeping is not some set-it-and-forget-it hobby where you can just put bees in a box and come back in a month to collect the goods. With the world’s bee population in decline, it’s more important than ever to monitor the health of hives.

One way to do that is to count the bees as they leave and reenter the hive. You can use the data to determine how many workers are working, or to compare activity between multiple hives. If you notice the bees are gone for longer and longer periods, it’s probably because their nearby nectar sources are dwindling and they have to travel farther to find flowers.

This open-source bee counter built by [hydronics2] is designed to fit the opening of a standard hive. The bees can only buzz themselves back in by flying through one of 24 little IR break-beam gates. Our favorite thing about this build is the way [hydronics2] created the individual gates by sandwiching two boards together with headers as spacers. It’s such a simple and perfect solution.

It’s also pretty cool that the board is designed to be compatible with any Feather or ItsyBitsy board, so there are a lot of options for data handling. Check out the brief demo we planted after the break, and stick around for the build video. If you’d prefer a more hands-off approach, try computer vision.

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Stylish Mic Is Metal Printing Done Right

March 21, 2020 by 9 Comments

[Eric Strebel] wanted a microphone to record voiceovers, and being a designer, wanted something suitably impressive for the task.  Inspired by the classic Unidyne 55, he set about designing his own mic, and used some pretty fancy techniques to get it built.

The mic was built around a ribbon element, providing good dynamic response. The design was created in CAD, and was initially intended to be constructed out of three seperate pieces. However, [Eric] realized that through the use of a binder jetting 3D printer, this wouldn’t be necessary.

Binder jetting is a technique in which a nozzle squirts binder into a powder bed to create a 3D printed part. In this case, a steel powder is used, which is then post-processed in an oven with liquid bronze. The bronze wicks into the finished part, adding strength. It’s a process which creates metal parts with very few limitations; the primary concern being minimum wall thicknesses.

With access to a binder jetting printer, [Eric] was free to design the stylish geometry of the final product. Mashing up hexagons with classic 50s curves, the final result is impressive. [Eric] now uses the microphone regularly to record voiceovers, and the aptly-named Hexavox even made an appearance at NAMM.

If you’re looking for more ways to DIY in your home studio, consider building your own isolation shield. Video after the break.

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Thermochromic Display Tells You The Temperature Despite Your Current Mood

March 20, 2020 by 8 Comments

Readers who survived the 1970s will no doubt remember the “mood ring” fad, where a liquid crystal mounted to a ring would magically reveal your current emotional state to all and sundry by changing color. This nifty thermochromic display is based on the same principle, and while it might not start a new craze, it’s still pretty mesmerizing to watch.

This isn’t [Moritz v. Sivers]’ first attempt at a thermochromic display. His earlier version was far more complicated, using separate copper plates clad with thermochromic film for each segment, with Peltier devices to cool and heat them individually. Version two is much simpler, using a printed circuit board with heating elements in the shape of seven-segment displays etched into it. The thermochromic film sits directly on the heater PCB; a control PCB below has the MCU and sensors on it. The display alternates between temperature and humidity, with the segments fading in an uneven and ghostly way that really makes this fun to watch. [Moritz] has made the build files available, and there’s a detailed Instructable as well.

We’re always on the lookout for alternate display modalities, especially when they look this cool. We’ve seen other thermochromic displays before, of course, and persistence of phosphorescence looks great, too.

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“Glixie” Puts A New Spin On Glow-In-The-Dark Displays

March 20, 2020 by 4 Comments

For as many projects as we see using Nixie tubes in new and unusual ways, there’s a smaller but often very interesting cohort of displays that fit into the “Nixie-like” category. These are projects where something other than the discharge of noble gasses is being used to form characters. This scrolling phosphorescent single-character display is one such project, and we think it looks fabulous.

Following the *ixie naming convention characteristic of these builds, [StephenDeVos] dubbed this the “Glixie.” This is on par with the size of a [Dalibor Farny] handmade Nixie, but not so big to be unwieldy. The display modality is glow-in-the-dark film that rotates past a vertical string of UV LEDs, which light up in turn as the cylinder rotates, building up the dot-matrix character column by column. There’s some fading of the first column by the time the whole character is built up, but not enough to be objectionable. We like the whole build, with laser-cut wood and the brass and steel hardware. Check it out in the video below.

If this phosphorescent display strategy seems familiar, it’s because we’ve seen it before. Remember this persistence of phosphorescence display? Or perhaps this time-writing robot clock? It’s not a new idea, but [Stephen]’s execution can’t be beat.

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Rubber Bands Can Secure Your Sanity

March 19, 2020 by 4 Comments

One of the greatest joys of being a child was figuring out that rubber bands make awesome sounds when they are plucked, and that the sound is easily changed by stretching the band to different lengths. For those of us who need firsthand experience to truly understand how the world works, these types of self-discovery are a pretty great way to learn about physics.

If you’re looking to build a physical music lesson or musical physics lesson into your burgeoning home school curriculum, look no further than the junk drawer, the broom closet, and the 3D printer. [Ham-made] used to stretch his bands across an empty tissue box, but came up with a much more professional implementation based on a broom handle. Check out this fat sound!

You don’t even need to find a spare broom handle, because none of this is permanent — the headstock piece with the hooks is meant to slide up and down to create cool sounds, and the tailpiece threads on in place of the broom bristles. Inside the tailpiece is a piezo disk and a 1/4″ jack so you can plug it in to your amp stack and start an impromptu jazz group. Just keep it under 10 people, okay?

You’ll need to mic your chanteuse, so keep the physics fun going with this plastic cup microphone.