In general, tattoo artists are not electrical engineers. That’s fine; the world needs both professions. But when you need a circuit designed, you’re better off turning to an EE rather than a tattoo artist. And you certainly don’t want an EE doing your new ink. Disaster lies that way.
Surprisingly, [Missa]’s tattoo of a heart-shaped circuit turned out at least to be plausible design, even if it’s not clear what it’s supposed to do. So her friend [Jeremy Elson] took up the challenge to create a circuit that looked like the tattoo while actually doing something useful. He had to work around the results of tattoo artistic license, like sending traces off to the board’s edge and stranding surface-mount components without any traces. The artist had rendered an 8-pin DIP device, albeit somewhat proportionally challenged, so [Jeremy] went with an ATtiny85, threw on a couple of SMD resistors and a cap, and placed two LEDs for the necessary blinkenlights. Most of the SMDs are fed from traces on the back of the board that resurface through vias, and a small coin cell hidden on the back powers it. One LED blinks “Happy Birthday [Missa]” in Morse, while the other blinks prime numbers from 2 to 23 – we’ll assume this means it was [Missa]’s 23rd birthday.
Holidays are always good for setting a deadline for finishing fun projects, and every Valentine’s Day we see projects delivering special one-of-a-kind gifts. Why buy a perishable bulk-grown biological commodity shipped with a large carbon footprint when we can build something special of our own? [Jiří Praus] certainly seemed to think so, his wife will receive a circuit sculpture tulip that blooms when she touches it.
This project drew from [Jiří]’s experience with aesthetic LED projects. His Arduino-powered snowflake, with LEDs mounted on a custom PCB, is a product available on Tindie. For our recent circuit sculpture contest, his entry is a wire frame variant on his snowflake. This tulip has 7 Adafruit NeoPixel in the center and 30 white SMD LEDs in the petals, which look great. But with the addition of mechanical articulation, this project has raised the bar for all that follow.
We hope [Jiří] will add more details for this project to his Hackaday.io profile. In the meantime, look over his recent Tweets for more details on how this mechanical tulip works. We could see pictures and short videos of details like the wire-and-tube mechanism that allowed all the petals to be actuated by a single servo, and the components that are tidily packaged inside that wooden base.
Radioactivity stirs up a lot of anxiety, partially because ionizing radiation is undetectable by any of the senses we were born with. Anytime radiation makes the news, there is a surge of people worried about their exposure levels and a lack of quick and accurate answers. Doctors are flooded with calls, detection devices become scarce, and fraudsters swoop in to make a quick buck. Recognizing the need for a better way, researchers are devising methods to measure cumulative exposure experienced by commodity surface mount resistors.
Cumulative exposure is typically tracked by wearing a dosimeter a.k.a. “radiation badge”. It is standard operating procedure for people working with nuclear material to wear them. But in the aftermath of what researchers euphemistically call “a nuclear event” there will be an urgent need to determine exposure for a large number of people who were not wearing dosimeters. Fortunately, many people today do wear personal electronics full of components made with high purity ingredients to tightly controlled tolerances. The resistor is the simplest and most common part, and we can hack a dosimeter with them.
Lab experiments established that SMD resistors will reveal their history of radiation exposure under high heat. Not to the accuracy of established dosimetry techniques, but more than good enough to differentiate people who need immediate medical attention from those who need to be monitored and, hopefully, reassure people in neither of those categories. Today’s technique is a destructive test as it requires removing resistors from the device and heating them well above their maximum temperature, but research is still ongoing in this field of knowledge we hope we’ll never need.
You can define the word crazy in myriad ways. Some would say using SMD resistors and QFN microcontrollers as structural elements is crazy. Some would say hand soldering QFN is crazy, much less trying to do it on edge rather than in the orientation the footprint is designed for. And of course doing it live on stage in front of people who eat flux for breakfast is just bonkers. But Zach did it anyway and I’m delighted he did.
This is the cyborg ring, and it’s a one-of-a-kind leap in imagination — the kind of leap people have come to expect from Zach Fredin who modeled neurons on PCBs, depopulated an SMD LED matrix and airwired it, and replaced his ThinkPad fingerprint reader with an ARM debugger port. The construction leverages the precise nature of manufactured parts: the ATtiny85 that drives the ring is exactly twice the width of an 0805 component. This means he can bridge the two circuit boards that make up the ring with the QFN microcontroller, and then use two 10M Ohm resistors as structural spacers in a few places around the ring. The jewels in this gem of a project are red LEDs that can be addressed in an animated pattern.
There’s an adage that all live talk demos are doomed to fail, and indeed the uC in this project doesn’t want to speak to the programmer at the end of the 9-minute exhibition. But Zach did manage to solder the two halves on the ring together live on stage, and it’s worth enduring the camera issues and low starting volume at the start of this livestream to watch him perform some crazy magic. Good on you Zach for putting yourself out there and showing everyone that there’s more than one way to stack resistors.
Conventional load cells, at least the ones you can pick up cheaply from the usual sources or harvest from old kitchen or bathroom scales, are usually way too big to be used on the extruder of a 3D-printer. [IvDm] wanted to build a touch sensor for his Hybercube printer, so he built his own load cell to do it. It consists of four 1000 ohm SMD resistors in the big 2512 device size. He mounted them to an X-shaped PCB and wired them in the classic Wheatstone bridge configuration, with two resistors on one side of the board and two on the other.
The extruder mounts into a hole in the center of the board and floats on it. Through an HX711 load cell driver chip, the bridge senses the slight flex of the board when the extruder bottoms out on the bed, and an ATtiny85 pulls a limit switch input to ground. [IvDm] even did some repeatability testing with this sensor and it turned out to be surprisingly consistent. The first minute or so of the video below shows it in action on the Hypercube.
We all have that friend who brings us their sad busted electronics. In [Leo’s] case, he had a MIDI sequencer from a musician friend. It had a dead display and the manufacturer advised that a driver IC was probably bad, even sending a replacement surface mount part.
[Leo] wasn’t convinced though. He knew that people were always pushing on the switches that were mounted on the board and he speculated that it might just be a bad solder joint. As you can see in the video below, that didn’t prove out.
The next step was to fire up a hot air gun. Instead of removing the chip, he wanted to reflow the solder anyway. He was a little worried about melting the 7-segment LEDs so he built a little foil shield to protect it. That didn’t get things working, either.
Making one of something is pretty easy, and making ten ain’t too bad. But what if you find yourself trying to make a couple of hundred of something on your home workbench? Suddenly, small timesavers start to pay dividends. For just such a situation, you may find these modular SMD tape feeders remarkably useful.
The tape feeders come in a variety of widths, to suit different size tapes. You’ve probably seen if you’ve ever ordered SMD components in quantity from Mouser, Digikey, et al. SMD components typically ship on large tape reels, which are machine fed into automated pick and place machines. However, if you’re doing it yourself in smaller quantities, having these manual tape feeders on your desk can be a huge help. Rather than having scraps of tapes scattered across the working surface, you can instead have them neatly managed at the edge of your bench, providing components as required.