Misc Hacks

4179 Articles

Hacking Touch Screens To Count Pulses

July 9, 2017 by 5 Comments

Heart rate sensors available for DIY use employ photoplethysmography which illuminates the skin and measures changes in light absorption. These sensors are cheap, however, the circuitry required to interface them to other devices is not. [Petteri Hyvärinen] is successfully investigating the use of capacitive touchscreens for heart rate sensing among other applications.

The capacitive sensor layer on modern-day devices has a grid of elements to detect touch. Typically there is an interfacing IC that translates the detected touches into filtered digital numbers that can be used by higher level applications. [optisimon] first figured out a way to obtain the raw data from a touch screen. [Petteri Hyvärinen] takes the next step by using a Python script to detect time variations in the data obtained. The refresh rate of the FT5x06 interface is adequate and the data is sent via an Arduino in 35-second chunks to the PC over a UART. The variations in the signal are very small, however, by averaging and then using the autocorrelation function, the signal was positively identified as a pulse.

A number of applications could benefit from this technique if the result can be replicated on other devices. Older devices could possibly be recycled to become low-cost medical equipment at a fraction of the cost. There is also the IoT side of things where the heart-rate response to media such as news, social media and videos could be used to classify content.

Check out our take on the original hack for capacitive touch imaging as well as using a piezoelectric sensor for the same application.

PCB Art Becomes Lapel Pins

July 7, 2017 by 17 Comments

We’re now living in the golden age of PCB art. Over the last year or so, the community has learned to manipulate silk screen, copper, and solder mask layers into amazing pieces of craftsmanship. These boards are putting the ‘A’ in STEAM, and now we have fiberglass replacements for enamel lapel pins.

[jglim] didn’t have much experience with fabric, but a PCB lapel pin was something that seemed like it should work. There are really only three parts to a lapel pin — the small ornamental pin itself, a solderable spike somehow attached to the pin (usually by soldering), and a clasp that holds the pin steadfastly to a lapel. The spike and clasp assembly were easily sourced on AliExpress, with one hundred clasps available for seven dollerydoos.  Attaching the spike to the PCB was as simple as adding a circular copper pad on the obverse side, applying some solder, and the liberal application of toaster ovens.

The design of the pin was based on the HTML5 logo, with the actual art done in Photoshop using a palette picked from OSHPark’s preview colors. The four colors used in this design are bare copper, a light purple for mask over copper, a darker purple for mask without copper, and a pale yellow for exposed FR4. This design was imported into KiCad with the Bitmap2Component tool.

The assembly of these lapel pins went very easily, and the finished product looks great. There’s a lot you can do with the standard OSHPark color stackup like making money of me, and this is a great example of exactly how much you can do with PCB art.

Camera Slide Pans And Tilts Camera Mechanically

July 5, 2017 by 22 Comments

A camera slider is a popular and simple project — just a linear slide, a stepper, and some sort of controller. Adding tilt and pan axes ups the complexity until you’ve got three motors, a controller, and probably a pretty beefy battery pack to run everything. Why not simplify with an entirely mechanical pan-tilt camera slider and leave all that heavy stuff at home?

There’s more than one way to program motion control, and [Enza3D]’s design uses adjustable rails to move the gimballed pan-tilt head through two axes of motion. One rail adjusts vertically to control tilt, while the other adjusts in and out relative to the slider to control pan. Arms ride on each rail and connect to the gimbals to swivel the camera in both dimensions while it travels down the manually cranked slide. It’s pretty clever and results in some clean, dynamic shots as in the video below.

Our quibble is that the “program” is only linear since the control rails are straight lengths of aluminum extrusion; seems to us that some sort of flexible control rails might make for more interesting shots. [Enza3D] has amply documented the build and is looking for feedback, so comment away. And if you don’t have a 3D printer to make the parts, wood works for a slider too.

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[Daito Manabe] Interview: Shocking!

July 5, 2017 by 2 Comments

We’ve loved [Daito Manabe]’s work for a while now. Don’t know [Daito]? Read this recent interview with him and catch up. Is he a hacker’s artist, or an artist’s hacker?

My personal favorite hack of his is laser painting apparatus from 2011. The gimmick is that he uses the way the phosphors fade out to create a greyscale image. Saying that is one thing, but watching it all come together in time is just beautiful.

Maybe you’ve seen his facial-electrocution sequencer (words we never thought we’d write! YouTube link). He’s taken that concept and pushed it to the limit — setting up the same sequences on multiple people make them look eerily like the sacks of meat that they are, until everyone laughs at the end of the experiment and they’re all back to being human.

Anyway, if you didn’t know [Daito], check out the rest of his work. Have any other favorite tech artists that we’re missing? Drop us a line.

Gecko Feet In Space

July 5, 2017 by 31 Comments

Space is a mess, and the sad truth is, we made it that way. Most satellites that have been lofted into Earth orbit didn’t have a plan for retiring them, and those dead hulks, along with the various bits of jetsam in the form of shrouds, fairings, and at least one astronaut’s glove, are becoming a problem.

A mission intended to clean up space junk would be fantastically expensive, but money isn’t the only problem. It turns out that it’s really hard to grab objects in space unless they were specifically designed to be grabbed. Suction cups won’t work in the vacuum of space, not everything up there is ferromagnetic, and mechanical grippers would have to deal with a huge variety of shapes, sizes, and textures.

But now news comes from Stanford University of a dry adhesive based on the same principle a gecko uses to walk up a wall. Gecko feet have microscopic flaps that stick to surfaces because of Van der Waals forces. [Mark Cutkosky] and his team’s adhesive works similarly, adhering to surfaces only when applied in a certain direction. This is an advantage over traditional pressure-sensitive adhesives; the force needed to apply them would cause the object to float away in space. The Stanford grippers have been tested on the “vomit comet” and aboard the ISS.

We can think of tons of terrestrial applications for this adhesive, including the obvious wall-walking robots. The Stanford team also lists landing pads for drones that would let then perch in odd locations, which we find intriguing.

Need to get up to speed on more mundane adhesive? Check out our guide to sticky stuff for the shop.

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A Shocking Wizard Duel

July 4, 2017 by 27 Comments

You’ve probably heard of Arthur C. Clarke’s third law, suggesting that any sufficiently advanced technology is indistinguishable from magic. Taking this literally and in the best possible way, [Allen Pan] of [Sufficiently Advanced] is using readily available technology to simulate magical wizarding duels in the fashion of Harry Potter.

Entitled the Wizard Analogue No-Magic Dueling Simulator — or W.A.N.D.S. for short — is a slightly more interactive version of laser tag. It’s especially engaging because your body is on the line. A Raspberry Pi using Google’s speech recognition service listens for the spell names and — remember, pronunciation is key — fires off the spell from an infrared LED tipped wand. Each duelist has five spells at their disposal, but their accuracy is up to you.

Once your opponent’s receiver registers a hit, an Arduino triggers transcutaneous electrical nerve stimulation (TENS) devices which sends pulses to various regions on the body to simulate the spell’s effect. What’s a few electrical shocks between wizards, eh?

As a defense from the constant barrage, the spell Protego — aimed at one’s own sensor — grants a few seconds immunity; however all spells have a built-in cool-down to prevent their abuse and an LED on the wand indicates when they’re ready to be used.

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