Embiggen your Eclipse 2017 Experience with a Sun Funnel

As exciting as Eclipse 2017 is going to be this Monday, for some folks it might appear a bit — underwhelming. Our star only occupies about half a degree of the sky, and looking at the partial phase with eclipse glasses might leave you yearning for a bigger image. If that’s you, you’ll need to build a sun funnel for super-sized eclipse fun.

[Grady] at Practical Engineering is not going to be lucky enough to be within the path of totality, but he is going to be watching the eclipse with a bunch of school kids. Rather than just outfitting his telescope with a filter and having the kids queue up for a quick peek, he built what amounts to a projection screen for the telescope’s eyepiece. It’s just a long funnel, and while [Grady] chose aluminum and rivets, almost any light, stiff material will do. He provides a formula for figuring out how long the funnel needs to be for your scope, along with plans for laying out the funnel. We have to take exception with his choice of screen material — it seems like the texture of the translucent shower curtain might interfere with the image a bit. But still, the results look pretty good in the video below.

Eclipse 2017 is almost here! How are you planning to enjoy this celestial alignment? By proving Einstein right? By studying radio propagation changes? Or just by wearing a box on your head? Sound off in the comments.

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Dedicated Button for Toggling Screens

Anyone who regularly presents to an audience these days has known the pain of getting one’s laptop to work reliably with projection hardware. It’s all the more fraught with pain when you’re hopping around from venue to venue, trying desperately to get everything functioning on a tight schedule. [Seb] found that the magic keystrokes they used to deal with these issues no longer worked on the Macbook Pro Touchbar, and so a workaround was constructed in hardware.

The build itself is simple – an Adafruit Trinket serves as the brains, with a meaty 12mm tactile button used for input. The Trinket emulates a USB keyboard and sends the Cmd-F1 keypress to the computer when the button is pressed. The button’s even mounted in a tidy deadbugged fashion.

While it’s not at all complicated from a build standpoint, the key to this project is that it’s a great example of using the tools available to solve real-life problems. When you’re in a rush with 300 people waiting for your talk to start, the last thing you need to be worrying about is a configuration issue. [Seb] now has a big red button to mash to get out of trouble and get on with the job at hand. It does recall this much earlier hack for emulating a USB keyboard with an Arduino Uno or Mega. It’s a useful skill to have!


Hacking Touch Screens to Count Pulses

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.

VR and Back Again: An XRobots Tale

Our friend [James Bruton] from XRobots has engaged in another bit of mixed-reality magic by showing how one can seamlessly step from the virtual world into the real world, and back again. Begone, green screens and cumbersome lighting!

Now, most of what you’re seeing is really happening in post-production — for now — but the test footage is the precursor for a more integrated system down the road. As it works now, a GoPro is attached to the front of a HTC Vive headset, allowing [Bruton] to record in both realities at the same time. In the VR test area he has set up is a portal to a virtual green room — only a little smaller than a wardrobe — allowing him to superimpose the GoPro footage over everything he looks at through that doorway, as well as everything surrounding him when he steps through. Unfortunately, [Bruton] is not able to see where he’s going if he is to wear the headset, so he’s forced to hold it in one hand and move about the mixed-reality space. Again, this is temporary.

In action — well, it gets a little surreal when he starts tossing digital blocks through the gateway ‘into’ the real world.

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Banana Phone Blocks Robocalls

Despite the implementation of the National Do Not Call Registry in the US (and similar programs in other countries), many robocallers still manage to get around the system. Whether they’re operating outside the law somehow (or they simply don’t care about it) there are some ways you can take action to keep these annoying calls from coming through. [Alex] is among those to take matters into his own hands and built a specialty robocall-blocking device.

Based on a Raspberry Pi, the “Banana Phone” is able to intercept incoming calls on standard land lines or VoIP phones. After playing a short message, the caller is asked to input a four-digit code. Once the code is correctly entered, the caller is presumed to be human, added to a whitelist, and then the Pi passes them on to the recipient. There are, however, some legitimate robocallers such as emergency services regarding natural disasters or utility companies regarding outages. For these there is a global whitelist that the Pi checks against and forwards these robocalls on to the recipient automatically.

This project was originally an entry into a contest that the Federal Trade Commission put on a few years ago for ideas about how to defend against robocalls. We covered it back then, but now there are full build instructions. Even though the contest is long over, the Banana Phone is still in active development so if you have a spare Pi lying around you can still set this up yourself. There are some other interesting ways to defend against robocalls as well, like including the “line disconnected” tone in your voicemail, for example.

Portable RetroPie Suitcase For Multiplayer On The Go!

Portable gaming — and gaming in general —  has come a long way since the days of the original Game Boy. With a mind towards portable multiplayer games, Redditor [dagcon] has assembled a RetroPie inside a suitcase — screen and all!

This portable console has almost everything you could need. Four controllers are nestled beside two speakers. Much of the power cabling is separated and contained by  foam inserts. The screen fits snugly into the lid with a sheet of rubber foam to protect it during transport.

Tucked behind the monitor rests the brains of this suitcase console: a Raspberry Pi and the associated boards. [Dagcon] resorted to using a dedicated sound card for the speakers, diverting the output from the HDMI port. An LCD screen controller was also necessary as the screen had been re-purposed from its previous life as a laptop screen. [Dagcon] offers some tips on how to go about accomplishing this yourself and a helpful Instructables link.

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