3D Printer Emission Monitor Quantifies The Stench

While we don’t yet know the long-term effects of hanging out around 3D printers, it doesn’t take a in-depth study to figure out that their emissions aren’t healthy. What smells toxic usually is toxic. Still, it’s oh-so-fun to linger and watch prints grow into existence, even when we have hundreds or thousands of hours of printing under our belts.

Most of us would agree that ABS stinks worse than PLA, and that’s probably because it releases formaldehyde when melted. PLA could be viewed as slightly less harmful because it has a lower melting point, and more volatile organic compounds (VOCs) are released at higher temperatures. Though we should probably always open a window when printing, human nature is a strong force. We need something to save us from our stubbornness, and [Gary Peng] has the answer: a smart 3D printer emission monitor.

The monitor continually checks the air quality and collects data about VOC emissions. As the VOCs become elevated during printing, the user is notified with visual, audio, and phone notifications. Green means you’re good, yellow means open a window, red means GTFO. There’s a brief demo after the break that also shows the phone interface.

The heart of this monitor is a CCS811 gas sensor, which provides VOC data to a Particle Photon. [Gary] built a simple Blynk interface to handle the alerts and graph historical VOC readings. He’s got the code and STLs available, so let this be the last time you watch something print in blissful semi-ignorance.

Concerned about air quality in general? Here’s a standalone portable monitor designed to quantify the soul-crushing stuffiness of meetings.

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A Pocket QWERTY For Arduino And More

If you want to add a keypad to your Arduino project, the options are pretty limited. There’s that red and blue 4×4 membrane we’ve all seen in password-protected door lock projects, and the phone layout version that does pretty much all the same tricks. Isn’t it time for a full Arduino-compatible keyboard? [ELECTRONOOBS] thinks so.

This 41-button Arduino keyboard PCB is a stepping stone to his next project, a pair of two-way texting machines. (Which is nice, because we were totally going to suggest that). It’s based on that ubiquitous red/blue keypad, but it has a full QWERTY layout. There’s also a shift button that opens up special characters and uppercase, and the addition of return, ok, and send keys puts it over the top. The best part of this keyboard, hands down, is the soft, soundless buttons. Though you trade clicky feedback for comfort, it will be well worth it after a few dozen presses.

The keypad uses an onboard ATMega328P to scan the matrix for button presses, decode them, and send them via UART or I²C to an Arduino. [ELECTRONOOBS] has the PCB files available via Patreon for now, though they will be open in the future. The code is already available for download on his website.

Future plans include an LED to indicate when shift is pressed, and adding the special characters next to the numbers on the silkscreen (whoops!). Be sure to check out the build video after the break.

Want an Arduino-driven keyboard for longer hauls across the alphabet? Saddle up and ride this candy-colored mechanical unicorn.

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Dian Fossey, Gorilla Girl

Few people sacrifice themselves as completely as Dian Fossey did for the mountain gorillas of Africa. She fought tirelessly to protect them from poachers, cattle herders, zoo kidnappers, corrupt governments, and tourists. Dian left a comfortable life behind to make the misty slopes of an extinct volcano her home and headquarters. There, she patiently sought out the gorillas, mimicking their facial expressions and actions until they grew curious about her. Eventually, she had their complete trust and friendship, and considered them her family.

Dian spent eighteen years on and off living among the gorillas. She continually risked her health, life, and reputation to raise awareness of their plight and save them from extinction. While the mountain gorilla remains an endangered species, Dian’s research and conservation efforts have greatly contributed to their increased population in the years since her death.

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Vintage Car Radio Now Plays Games And Chiptunes

[MisterM] seems to specialize in squeezing new electronics into old but good-looking technology. His latest creation focuses on a space-age specimen: an interesting car radio from 1963 that could be pulled out from the dashboard and taken along wherever. The beat goes on, thanks to a shiny built-in speaker on the bottom.

He replaced the non-working radio guts with a Raspberry Pi 3 running RetroPie and a Picade controller board. A Pimoroni Blinkt LED strip behind the radio dial glows a different color for each emulated console, which we think is a nice touch. [MisterM] built this console to play in his workshop, and even made a dock for it. But in a lovely homage to the original radio, it’s self-contained and can be taken to the living room or to a friend’s house. There’s also a USB port for whenever player two is ready to enter. For [MisterM]’s next trick, he’ll be converting an 80s joystick.

We love that [MisterM] repurposed the dials as housings for start and select buttons. As he points out, this keeps them out of the way while he’s wildly working the controls. Just enter the Konami Code to unlock the build video below.

Do you dream of playing Donkey Kong absolutely everywhere? Check out the ultraportable mintyPi 2.0.

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Candy-Colored Synth Sounds Sweet

Let’s face it, synthesizers are awesome. But commercial synths are pretty expensive. Even the little toy ones like the KORG Volca and the MicroKORG will run you a few hundred bucks. For the most part, they’re worth the price because they’re packed with features. This is great for experienced synth wizards, but can be intimidating to those who just want to make some bleeps and bloops.

[Kenneth] caught the mini-synth bug, but can’t afford to catch ’em all. After a visit to the Moog factory, he was inspired to engineer his own box based on the Moog Sirin. The result is KELPIE, an extremely portable and capable synth with 12 voices, 16 knobs, and 4 LED buttons. KELPIE is plug and play—power and a MIDI device, like a keyboard, are the only requirements. It has both 1/8″ and 1/4″ jacks in addition to a standard MIDI DIN connection. [Kenneth] rolled his own board based on the Teensy 3.2 chip and the Teensy audio shield.

Part of the reason Kenneth built this synthesizer is to practice designing a product from the ground up. Throughout the process, he has tried to keep both the production line and the DIYer in mind: the prototype is a two-part resin print, but the design could also be injection molded.

We love that KELPIE takes its visual design cues from the translucent candy-colored Game Boys of the late 90s. (We had the purple one, but always lusted after the see-through kind.)  Can we talk about those knobs? Those are resin-printed, too. To color the indicators, [Kenneth] used the crayon technique, which amounts to dripping molten crayon into the groove and scraping it off once hardened. Don’t delay; glide past the break to watch a demo.

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Air Hockey Table Is A Breeze To Build

Many of us have considered buying an air hockey table, but are put off by the price. And even if the money is there, those things take up a lot of space. How often are you really going to use it?

This DIY air hockey table is the answer. It’s big enough to be fun, but small and light enough to easily stow away in the off-season. At ~$50, it’s a cheap build, provided you have a vacuum cleaner that can switch to blower mode. The strikers, goals, corner guards, and scoreboard enclosure are all 3D-printed, while the pucks and playfield are laser-cut acrylic. [Technovation] glued acrylic feet to the strikers to help them last longer.

The scoreboard is an Arduino Uno plus an LCD that changes color to match the current winner. Scoring must be entered manually with button presses, but we think it would be fairly easy to detect a puck in the goal with a force or weight sensor or something. For now, the RGB LEDs around the edge are controlled separately with a remote. The ultimate goal is to make the Arduino do it. Shoot past the break and cross-check it out.

Already have a table? Had it so long, no one will play you anymore? Build yourself a robotic opponent.

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Be Better Bracelet Breaks Bad Habits, Fosters Favorable Fixations

Do you want to be a better person? Maybe you want to curse less, drink more water, or post fewer inflammatory comments on the internet. You could go the old school route by wearing a rubber band around your wrist and snapping it every time you slip, or literally pat yourself on the back when you do the right thing. While these types of reinforcement methods may deter bad behavior and encourage good, they are quite lean on data. And who wants that?

After an unpleasant conference call, [Darian] cursed a blue streak that left his coworkers shocked and speechless. This inciting incident began the hero’s journey that will end with a kinder, gentler [Darian], as long as he has his trusty Be Better Bracelet. He tried involving Alexa when at home, and various apps elsewhere to track these venomous utterances, but he yearned for a single solution that’s always available.

The sole purpose of this bracelet is low-cost, unobtrusive habit tracking. Though tied to a phone, it won’t tell time, predict the weather, or alert the user to incoming what-have-yous. It will simply record button presses, which are assigned meaning in the app settings. It’s up to the user to set goals, analyze the data, and reward or punish themselves accordingly.

[Darian] is still working out the design kinks to make this as small and cheap as possible. If you have suggestions, let him know.