NFC Enabled Business Card

[Sjaak] is back at it again with the cool PCB business cards, this time alleviating the burden to physically type his contact information into your phone. But NFC isn’t the only cool thing on this PCB – as always, his aesthetics don’t disappoint.

When we see [Sjaak’s] card, the future seems to be the now – not only do we have business cards that can take our pulse, we have business cards that actively help facilitate the exchange of contact information. I know what you’re thinking. “Business cards made of paper do that already.” That’s true if you read them. You have to physically remember you have the card (aka not put it through the wash), and, if you’re like most folks, you’ll ultimately enter the information into your cell phone’s contact list. Why not skip the whole reading thing? You know, just zap your contact information into the contact list of people automatically?

Maybe this is exactly what [Sjaak] thought when he built his NFC enabled business card. Maybe not. Regardless, [Sjaak’s] card is beautiful – both in implementation and aesthetics. Powered by “a nice little NFC EEPROM from NXP”, (the NT3H1101) the business card even has an energy harvesting mode. Moreover, one can interact with the card via four buttons and an LED. The LED informs the user what mode the card is currently in, and the buttons choose which URL is sent to users via NFC. To add icing to the cake, the back of the PCB is decked out via [Sjaak’s] custom full-color decal process we covered back in August.

As great as it looks, the card still needs some improvement. “I still need to tackle the sharp and protruding components on the front, which will ruin your wallet.” But, in our eyes, the card is surely on its way to greatness, and we look forward to seeing its final form. However, if you’re anything like us, you might want to see some other rad PCB business cards while you wait. If that’s the case, we recommend this logic based finite machine and this card made by a hackaday author.

World’s Largest Telescope Stopped by LED

Earlier this year a simple indicator LED brought the Keck 1 telescope, a 370 tons mass, to a halting stop. How exactly did an LED do this? Simple: it did nothing.

As it so happens, [Andrew Cooper] was just about the leave the summit of Mauna Kea (in Hawaii) when his radio instructed him otherwise: there was an issue. Upon returning, [Andrew] was met by a room of scientists and summit supervisors. “Yeah, this was not good, why are they all looking at me? Oh, h%#*!” The rotor wasn’t moving the telescope, and “no rotator equals no science data.” After being briefed on the problem, [Andrew] got to work. Was it a mechanical issue? No: manual mode worked quite fine, also indicating that the amplifiers and limit switches are functional as well.

Jumping from chip to chip, [Andrew] came across an odd voltage: 9.36V. In the CMOS [Andrew] was investigating, this voltage should have High (15V) or Low (0v) and nowhere in between. Judging by the 9.36V [Andrew] decided to replace the driving IC. One DS3632 later, nothing had changed. Well, maybe is one of the loads pulling the line low? With only two choices, [Andrew] eliminated that possibility quickly. Likely feeling as if he was running out of proverbial rope, [Andrew] remembered something important: “the DS3236 driving this circuit is an open collector output, it needs a pull-up to go high.”

Reviewing the schematic, [Andrew] identified the DS3236’s pull-up: an LED and its current limiting resistor. While the carbon composition resistor was “armageddon proof,” [Andrew] was suspicious of the LED. “Nick, can you get me a 5k resistor from the lab?” Hold the resistor on the pins of the chip and the amplifiers immediately enabled.

[Andrew] summarizes things quite well: “yes… One of the world’s largest telescopes, 370 tons of steel and glass, was brought to a halt because of a bad indicator LED”. It stopped things by doing nothing, or rather, by not turning on.

We love it when we get troubleshooting stories, and if you share our interest in problem-solving, check out this broken power supply troubleshooting or learn what could go wrong with I2C.

Edit: Keck 1 is one of the largest optical telescopes in the world. Thanks to [Josh] for noticing our error.

A BluePill for Arduino Dependence

Arduinos are helpful but some applications require more than what Arduinos can provide. However, it’s not always easy to make the switch from a developed ecosystem into the abyss that is hardware engineering. [Vadim] noticed this, which prompted him to write a guide to shepherd people on their quest for an Arduino-free environment, one BluePill at a time.

With an extended metaphor comparing Arduino use and physical addiction, [Vadim’s] writing is a joy to read. He chose to focus on the BluePill (aka the next Arduino Killer™) which is a $1.75 ARM board with the form factor of an Arduino Nano. After describing where to get the board and it’s an accompanying programmer, [Vadim] introduces PlatformIO, an alternative to the Arduino IDE. But wait! Before the Arduino die-hards leave, take note that PlatformIO can use all of the “Arduino Language,” so your digitalWrites and analogReads are safe (for now). Like any getting started guide, [Vadim] includes the obligatory blinking an LED program. And, in the end, [Vadim] sets his readers up to be comfortable in the middle ground between Arduino Land and the Wild West.

The debate for/against Arduino has been simmering for quite some time, but most agree that Arduino is a good place to start: it’s simpler and easier than jumping head first. However, at some point, many want to remove their “crippling Arduino dependency” (in the words of [Vadim]) and move on to bigger and better things. If you’re at this point, or still cling to your Uno, swing on over and give Vadim’s post a read. If you’re already in the trenches, head on over and read our posts about the BluePill and PlatformIO which are great complements for [Vadim’s].

3D Printing T-Shirt Designs

Usually, t-shirt designs are screen printed, but that’s so old school. You have to make the silkscreen and then rub paint all over – it’s clearly a technique meant for the past. Well, fear not, as [RCLifeOn] is here to bring us to the future with 3D Printed T-Shirt Designs.

[RCLifeOn] affixes t-shirts to his print build platform and boom: you’ve got 3D printed graphics. He started by using PLA which, while it looked great, wasn’t up to a tussle with a washing machine. However, he quickly moved on to NinjaFlex which fended much better in a wash cycle. While the NinjaFlex washed better, [RCLifeOn] did have some issues getting the NinjaFlex to adhere to the t-shirt. With a little persistence and some settings tweaking, he was able to come out ahead with a durable and aesthetically pleasing result.

Now, 3D printing isn’t going to replace screen printing, but it’s also not going to replace injection molding. What 3D printing lacks in speed and efficiency, it makes up in setup time & cost. In other words, if you need 50 t-shirts of the same design, screen printing is the way to go. But, if you need 50 shirts, each with a different design, you just might want to follow in [RCLifeOn’s] footsteps.

Anyways, we don’t have much on 3D printing t-shirts, but we do have other useful information on 3D printing slinkys and 3D printing project enclosures. And, if you’d rather do it the old-school way, we can show you how to silkscreen all the things.

A Detailed Guide for 3D Printing Enclosures

We’ve all have projects that are done, but not complete. They work, but they’re just a few PCBs wired together precariously on our desks. But fear not! A true maker’s blog has gifted us with a detailed step-by-step guide on how to make a project enclosure.

Having purchased an MP Select Mini 3D Printer, there was little to do but find something practical to print. What better than an enclosure for a recently finished Time/Date/Temperature display Arduino based device?

The enclosure in this guide, while quite nice, isn’t the main attraction here. The real feature is the incredibly detailed instructions for how to design, model and print an enclosure for any project. For the veterans out there, it seems simple. Sketch something on the back of a napkin and take a nap on your keyboard with OpenSCAD open. When you wake, BAM: perfect 3D model. However, for newcomers, the process can seem daunting. With incredibly specific instructions (an example is “Open up a new workspace by clicking CREATE NEW DESIGN,” notice the accurate capitalization!), it should ease the barrier of the first enclosure, turning the inexperienced into the kind-of-experienced.

If you’ve been printing enclosures since the dawn of time or plastic simply isn’t your style, boy, do we have you covered. Why not check out FR4 (aka PCB) enclosures? Or what about laser cut enclosures from eagle files? Maybe two-piece boxes are more your thing.

Living Logic: Biological Circuits for the Electrically Minded

Did you know you can build fundamental circuits using biological methods? These aren’t your average circuits, but they work just like common electrical components. We talk alot about normal silicon and copper circuits ‘roud here, but it’s time to get our hands wet and see what we can do with the power of life!

In 1703, Gottfried Wilhelm Leibniz published his Explication de l’Arithmétique Binaire (translated). Inspired by the I Ching, an ancient Chinese classic, Leibniz established that the principles of arithmetic and logic could be combined and represented by just 1s and 0s. Two hundred years later in 1907, Lee De Forest’s “Audion” is used as an AND gate. Forty years later in 1947, Brattain and H. R. Moore demonstrate their “PNP point-contact germanium transistor” in Bell Labs (often given as the birth date of the transistor). Six years later in 1953, the world’s first transistor computer was created by the University of Manchester. Today, 13,086,801,423,016,741,282,5001 transistors have built a world of progressing connectivity, automation and analysis.

While we will never know how Fu Hsi, Leibniz, Forest or Moore felt as they lay the foundation of the digital world we know today, we’re not completely out of luck: we’re in the midst’s of our own growing revolution, but this one’s centered around biotechnology. In 1961, Jacob and Monod discovered the lac system: a biological analog to the PNP transistor presented in Bell Labs fourteen years earlier. In 2000, Gardner, Cantor, and Collins created a genetic toggle switch controlled by heat and a synthetic fluid bio-analog2. Today, AND, OR, NOR, NAND, and XOR gates (among others) have been successfully demonstrated in academic labs around the world.

But wait a moment. Revolution you say? Electrical transistors went from invention to computers in 6 years, and biological transistors went from invention to toggle button in 40? I’m going to get to the challenges facing biological circuits in time, but suffice it to say that working with living things that want to be fed and (seem to) like to die comes with its own set of challenges that aren’t relevant when working with inanimate and uncaring transistors. But, in the spirit of hacking, let’s dive right in. Continue reading “Living Logic: Biological Circuits for the Electrically Minded”

New Method for Measuring Lots of Resistors Using Very Few Wires

[Daqq] is back at it again with the linear algebra, and he’s now come up with a method for determining the resistance of lots of resistors using little of wires and loads of math.

Like any reasonable person, [daqq] decided it would be fun to “solve one of those nasty [electrical engineering] puzzles/exercises where you start out with a horrible mess of wires and resistors and you are supposed to calculate the resistance between two nodes.” You know, just an average Saturday night. At the time, he was also fascinated by Charlieplexing – an awesome technique that either allows one to control multiple polarized components, such as LEDs, simply by connecting them in a specific way. After toying with the idea for a while, [daqq] found that using just Charlieplexing would be“a horrible mess” but he didn’t stop there. Drawing inspiration from Charlieplexing, he came up with the idea to connect things in such a way that every node is connected by one connection to every other node – a complete graph from a topological view point (this makes so much more sense visually). From here, he was able to set pins to HIGH, LOW, or INPUT and gather all the data needed to solve his linear system of equations.

Now, there is a balance to everything, and while this system can determine the resistance of .5*N(N-1) resistors using just N wires, it also a memory and computation hungry method. Oh well, can’t have it all. But, while it’s computationally hungry, [daqq] got it working on an ATMega32, so it’s not an unmanageable feat. And, let’s not forget to mention [daqq’s] wonderful writing. Even if you don’t know linear algebra (or would rather forget), it’s a good read from a theory perspective. So good, in fact, that [daqq] is getting published in Circuit Cellar!

We love to see theory in the hacker world, so keep it coming! But, while we wait (wink wink), there’s always time to review the basic Hacker Calculus and check out our past math-related articles.