Whirling Shutters On This Field Mill Measure Electrostatic Charges At Distance

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

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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Monochrome CRT And Liquid Crystal Shutter Team Up For Color Video

If you were tasked with designing a color video monitor, it’s pretty clear how you’d go about it. But what if you’d been asked to do so 20 years ago? Would it have been a cut and dried from an engineering standpoint? Apparently not, as this hybrid LCD-CRT video monitor demonstrates.

We’d honestly never heard of this particular design, dubbed “LCCS”, or liquid crystal color shutter, until [Technology Connections]’ partial teardown of the JVC monitor and explanation of its operation. The idea is simple and hearkens back to the earliest days of color TV in the United States, when broadcasters were busy trying to bring color to a monochrome world in a way that would maximize profits. One scheme involved rotating a color wheel in front of the black-and-white CRT and synchronizing the two, which is essentially what’s happening in the LCCS system. The liquid crystal panel cycles between red, blue, and green tints in time with the CRT’s images behind it, creating a full-color picture. “But wait!” you cry. “Surely there were small color CRTs back in the year 2000!” Of course there were, but they kind of sucked. Just look at the comparison of a color CRT and the LCCS in the video below and you’ll see why this system carved out a niche in the pro video market, especially for video assist monitors in the days before digital cinematography. A similar system was used by Tektronix for color oscilloscopes, too.

As usual, [Technology Connections] has managed to dig up an interesting bit of the technological fossil record and present it in a fascinating way. From video on vinyl to 1980s copy protection to the innards of a toaster, we enjoy the look under the hood of forgotten tech.

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Painting With Light And A Little G-Code

Most photographs are made in the fraction of a second that the camera’s shutter is gathering reflected light from the scene. But there’s fun to be had by leaving the shutter open and directing light into the camera. Called light painting, it can be as simple as a camera on a tripod in a dark room and a penlight spelling out dirty words – not like we’d know – or as complicated as this CNC dot-matrix light printer.

The first idea that [Jeremy S. Cook] had for this build didn’t go so well. He fitted an LED to the gantry of his 3D-printer, intending to send it G-code representing bitmaps. The idea would be to set it up in a dark place, open the shutter, and let the machine build up the image by rastering through the X- and Y- axes while blinking the LED on and off at the right time. But since the gantry only moves in one axis, he abandoned the printer in favor of his CNC router. He printed a collar to fit the dust collector shroud we previously featured, added a battery-powered LED, and affixed a pushbutton switch to the let the Z-axis turn on the light. It took some tweaking such as adding a translucent PLA diffuser, to get decent images, but in the end it worked. We like the soft look of the floating voxels, which were really helped by the later addition of a Nano and a Neopixel. Check out the build in the video below.

One thing we’d suggest is better reflection control. [Jeremy] used a black platen as a background, but it wasn’t quite enough. We suggest going none more black next time.

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Laser Light Show Turned Into Graphical Equalizer

The gold standard for laser light shows during rock concerts is Pink Floyd, with shows famous for visual effects as well as excellent music. Not all of us have the funding necessary to produce such epic tapestries of light and sound, but with a little bit of hardware we can get something close. [James]’s latest project is along these lines: he recently built a laser light graphical equalizer that can be used when his band is playing gigs.

To create the laser lines for the equalizer bands, [James] used a series of mirrors mounted on a spinning shaft. When a laser is projected on the spinning mirrors it creates a line. From there, he needed a way to manage the height of each of the seven lines. He used a series of shrouds with servo motors which can shutter the laser lines to their appropriate height.

The final part of the project came in getting the programming done. The brain of this project is an MSGEQ7 which  takes an audio input signal and splits it into seven frequencies for the equalizer. Each one of the seven frequencies is fed to one of the seven servo-controlled shutters which controls the height of each laser line using an Arduino. This is a great project, and [James] is perhaps well on his way to using lasers for other interesting musical purposes.

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Shutter Bug Goes Extreme With Scratch-Built Film Camera

Should a camera build start with a sand mold and molten aluminum? That’s the route [CroppedCamera] took with this thoroughly impressive camera project.

When we think of cameras these days, chances are we picture the ones that live inside the phones in our pockets. They’re the go-to image capture devices for most of us, but even for the more photographically advanced among us, when a more capable camera is called for, it’s usually an off-the-shelf DSLR from Canon, Nikon, or the like. Where do hand-built cameras fall in today’s photography world? They’re a great way to add a film option to your camera collection.

[CroppedCamera] previously built a completely custom large-format view camera, but for this build he decided that something a bit more portable might do. The body of the camera is scratch-built from aluminum, acting as the lightproof box to hold the roll film and mount the leaf-shutter lens. There’s an impressive amount of metalwork here — sand casting, bending, TIG welding, and machining all came into play, and most of them new skills to [CroppedCamera]. We were especially impressed with the shrink-fit of the lens cone to the body. It’s unconventional looking for sure, but not without its charm, and it’s sure to make a statement dangling around his neck.

It’s tough to find non-digital DIY camera builds around here — best we could do were these laser-cut plywood modular cameras. Then again, you can’t beat this wearable camera for functional style.

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Full SHTTTRRR Control Lets You Take Your Time…

[Glitchmaker] loves photography and wrote in to tell us about his newest project. He has a Canon 1000D camera but, unfortunately, it does not have time lapse capability. So, instead of shelling out a chunk of change for a new camera [Glitchmaker] decided to make an external shutter control device that can continue to instruct the camera to take photos at predetermined intervals. He calls his project: SHTTTRRR. You didn’t think that meant something else, did you?

You can see the unassuming box above, there is just enough stuff packed in there to get the job done, nothing extra or fancy. Luckily, the Cannon camera has a remote shutter input jack that only requires connecting one pin to another in order to take a photo. Inside the box is an ATTINY45 microcontroller. It reads the button pushes from the single panel-mounted button and calculates the time between two button presses. That time between button presses determines the frequency of the photos taken. At the appropriate times, the ATTINY45 signals a transistor to connect the two appropriate pins on the camera’s remote shutter input jack. The device continues to tell the camera to take photos until it is shut off. The result is a series of time-lapse photos that was previously not possible on that camera!

This is a simple project that solves a problem and gets the job done. What’s better than that? [Glitchmaker] is proud of the SHTTTRRR he made and also learned a bunch about programming the ATTINY45 along the way. Check a video of it working after the break.

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