Hackaday Prize Entry: Printem Is Polaroid For PCBs

We are going to great lengths to turn a quick idea into an electronic prototype, be it PCB milling, home etching or manufacturing services that ship PCBs around the world. Unwilling to accept the complications of PCB fabrication, computer science student [Varun Perumal Chadalavada] came up with an express solution for PCB prototyping: Printem – a Polaroid-like film for instant-PCBs.

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HTC Vive Gives Autonomous Robots Direction

The HTC Vive is a virtual reality system designed to work with Steam VR. The system seeks to go beyond just a headset in order to make an entire room a virtual reality environment by using two base stations that track the headset and controller in space. The hardware is very exciting because of the potential to expand gaming and other VR experiences, but it’s already showing significant potential for hackers as well — in this case with robotics location and navigation.

Autonomous robots generally utilize one of two basic approaches for locating themselves: onboard sensors and mapping to see the world around it (like how you’d get your bearings while hiking), or sensors in the room which tell the robot where it is (similar to your GPS telling you where you are in the city). Each method has its strengths and weaknesses, of course. Onboard sensors are traditionally expensive if you need very accurate position data, and GPS location data is far too inaccurate to be of use on a smaller scale than city streets.

[Limor] immediately saw the potential in the HTC Vive to solve this problem, at least for indoor applications. Using the Vive Lighthouse base stations, he’s able to locate the system’s controller in 3D space to within 0.3mm. He’s then able to use this data on a Linux system and integrate it into ROS (Robot Operating System). [Limor] hasn’t yet built a robot to utilize this approach, but the significant cost savings ($800 for a complete Vive, but only the Lighthouses and controller are needed) is sure to make this a desirable option for a lot of robot builders. And, as we’ve seen, integrating the Vive hardware with DIY electronics should be entirely possible.

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Charliplexed 7-Segment Display Takes Advantage Of PCB Manufacturers

Cutting out precise shapes requires a steady hand, a laser cutter, or a CNC mill, right? Nope! All you need is PCB design software and a fabrication facility that’ll do the milling for you. That’s the secret sauce in [bobricius]’s very pleasing seven-segment display design.

His Hackaday.io entry doesn’t have much detail beyond the pictures and the board files, but we’re not sure we need that many either. The lowest board in the three-board stack has Charlieplexed LEDs broken out to six control pins. Next up is a custom-routed spacer board — custom routed by the PCB house, that is. And the top board in the stack is another PCB, this one left clear of copper where the light shines out.

We want to see this thing lit up! We’ve played around with using PCB epoxy material as a LED diffuser before ourselves, and it can look really good. The spacers should help even out the illumination within segments, while preventing bleed across them. Next step? A matrix of WS2812s with custom-routed spacers and diffusers. How awesome would that be?

Time Lapse Rig Puts GoPro Into Orbit – In Your Shop

The combination of time-lapse photography and slow camera panning can be quite hypnotic – think of those cool sunset to nightfall shots where the camera slowly pans across a cityscape with car lights zooming by. [Frank Howarth] wanted to replicate such shots in his shop, and came up with this orbiting overhead time-lapse rig for his GoPro.

[Frank] clearly cares about the photography in his videos. Everything is well lit, he uses wide-open apertures for shallow depth of field shots, and the editing and post-production effects are top notch. So a good quality build was in order for this rig, which as the video below shows, will be used for overhead shots during long sessions at the lathe and other machines. The gears for this build were designed with [Matthias Wandel]’s gear template app and cut from birch plywood with a CNC router. Two large gears and two small pinions gear down the motor enough for a slow, smooth orbit. The GoPro is mounted on a long boom and pointed in and down; the resulting shots are smooth and professional looking, with the money shot being that last look at [Frank]’s dream shop.

If you haven’t seen [Frank]’s YouTube channel, you might want to check it out. While his material of choice is dead tree carcasses, his approach to projects and the machines and techniques he employs are great stuff. We featured his bamboo Death Star recently, and if you check out his CNC router build, you’ll see [Frank] is far from a one-trick pony.

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All About Biosignals

DIY medical science is fun stuff. One can ferret out many of the electrical signals that make the body run with surprisingly accessible components and simple builds. While the medical community predictably dwells on the healthcare uses of such information, the hacker is free to do whatever he or she wants.

A good first start is to look at the relatively strong electrical signals coming off of the heart and other muscles. [Bernd Porr] has put together a simple bioamplifier circuit, and his students have made a series of videos explaining its use that’s well worth your time if you are interested in these things.
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RGB LEDs: How To Master Gamma And Hue For Perfect Brightness

You would think that there’s nothing to know about RGB LEDs: just buy a (strip of) WS2812s with integrated 24-bit RGB drivers and start shuffling in your data. If you just want to make some shinies, and you don’t care about any sort of accurate color reproduction or consistent brightness, you’re all set.

But if you want to display video, encode data in colors, or just make some pretty art, you might want to think a little bit harder about those RGB values that you’re pushing down the wires. Any LED responds (almost) linearly to pulse-width modulation (PWM), putting out twice as much light when it’s on for twice as long, but the human eye is dramatically nonlinear. You might already know this from the one-LED case, but are you doing it right when you combine red, green, and blue?

It turns out that even getting a color-fade “right” is very tricky. Surprisingly, there’s been new science done on color perception in the last twenty years, even though both eyes and colors have been around approximately forever. In this shorty, I’ll work through just enough to get things 95% right: making yellows, magentas, and cyans about as bright as reds, greens, and blues. In the end, I’ll provide pointers to getting the last 5% right if you really want to geek out. If you’re ready to take your RGB blinkies to the next level, read on!

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Compact EPaper Business Card

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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