Secret Bookshelf Door Uses Hidden Fingerprint Scanner

May 30, 2023 by Zoe Skyforest 4 Comments

What is it that compels us about a secret door? It’s almost as if the door itself and the promise of mystery is more exciting than whatever could lay beyond. In any case, [Scott Monaghan] is a lover of the form, and built his own secret door hidden in a bookshelf, as all good secret doors should be.

The door is activated by pulling down on the correct book. This then reveals a fingerprint scanner. Upon presenting the right digit, the door will elegantly swing open to reveal the room beyond. Secret door experts will note there’s an obvious tell due to the light spilling through the cracks, however [Scott] reports that the finishing stages of the build solved this issue. The door was also fitted with a manual release for easier daily use.

Details are light, but the basics are all there. Really all you need is a cheap hardware store door opener, a secret activation lever or authentication method, and a well-hinged bookcase to achieve this feat yourself. We’ve seen some other great secret doors before, too. Video after the break.

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Pretty Small Robot Is Capable, Nonetheless

May 30, 2023 by Zoe Skyforest 5 Comments

When science fiction authors imagined robots in the 20th century, many of them were huge imposing steel automatons. [Shane]’s designs for the Pretty Small Robot are quite contrary to that, being tiny in stature and cute in affect .

The whole robot is an exploration in nifty engineering. It uses an easy clip-together structure with fasteners and glue not required. The chassis is 3D printed, with all the components sliding into place. Two small DC gearmotors are used for differential drive, with each side of the robot having a pair of wheels wrapped in a rubber band for traction. The brains of the robot is an ESP32, providing it with both plenty of processing power and good connectivity options. Control is over WiFI via MQTT.

At this stage the robot doesn’t do a whole lot, though [Shane] has some exciting plans. He’d like to add a camera in future and let it explore a maze under human command.

If you’ve ever wanted to build a robot with an almost coin-sized foot print, this build is for you. Files are available on GitHub for those wishing to dive deeper. Video after the break.

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Ultimate Garage Door Control Does The Job Brilliantly

May 30, 2023 by Zoe Skyforest 21 Comments

[Stephen Carey] had previously relied on an Insteon garage door controller, only to have it perform poorly and fail at integrating with Alexa properly. Thus, he did what any good hacker would do, and built his own system instead.

The garage door was first outfitted with a pair of reed switches to sense when it was fully open or fully closed. The drive sprocket of the garage door was also set up to be monitored with magnets and Hall effect sensors, essentially creating a rotary encoder. This allows a ESP32 to monitor the door’s direction of travel, it’s position, and when it has hit the end stop in either direction. Using Micropython, [Stephen] whipped up some code to tie the garage door controls in with Home Assistant, complete with a neat visual display of the current door position.

There are millions of home automation products out there, many of which make annoying compromises that frustrate the end user. Sometimes, doing it your own way is the only way to get satisfaction!

Methane-Tracking Satellites Hunt For Nasty Greenhouse Gas Emissions

May 30, 2023 by Zoe Skyforest 41 Comments

Much of the reporting around climate change focuses on carbon dioxide. It’s public enemy number one when it comes to gases that warm the atmosphere, as a primary byproduct of fossil fuel combustion.

It’s not the only greenhouse gas out there, though. Methane itself is a particularly potent pollutant, and one that is being emitted in altogether excessive amounts. Satellites are now on the hunt for methane emissions in an attempt to save the world from this odorless, colorless gas.

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The Art And Science Of Making Beautiful Transparent Ice

May 24, 2023 by Zoe Skyforest 43 Comments

For most of us, ice isn’t something we’ve thought about in detail since our high school science classes. For most of us, we pour some tap water into the ice trays, slam it in the freezer, and forget about it. Then we lob the frozen misshapen cubes into a beer and enjoy a quite literally ice-cold beverage.

However, there’s so much more fun to be had with ice if you really get into it. If you’ve ever wondered how pretentious cocktail bars make their fancy ice spheres or transparent cubes, read on!

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Smart Pants Sound Alarm When Your Fly Is Undone

May 23, 2023 by Zoe Skyforest 28 Comments

It’s always embarrassing to be told your fly is down. Even moreso when you realize it’s been that way since you returned from the bathroom an hour ago. [Guy Dupont] has built a device to solve this awkward issue once and for all. (Nitter)

Pictured: The Hall effect sensor and magnet attached to the zipper.

The pants contain a Hall effect sensor which has been attached inside the fly of the jeans, at the bottom of the zipper. The zipper pull itself was then fitted with a strong magnet, which triggers the sensor when the zipper is in the open position. An ESP32 in the pocket of the jeans is tasked with monitoring the sensor. If it detects that the zipper has been down for too long, it sends a notification to the wearer’s smartphone to zip up. We kind of wish they’d sound an ear-splitting klaxon, but that might draw undesired attention to the wearer.

Zipper position monitoring seems like a nightmare at first, but [Guy]’s hack shows us that it’s actually trivial with this method. The system does, however, add significant complication to what was previously a totally-analog pair of pants. Don’t expect “Big Jeans” to jump on this tech, as maintenance and waterproofing issues would likely make the hardware a pain to deal with in real life.

Plus, just imagine the frustration every morning. “Sorry, mate, not ready to head out yet – I’ve gotta pair my jeans with my smartphone.”

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Building A Breath-Controlled MIDI Device

May 19, 2023 by Zoe Skyforest 6 Comments

When we think of MIDI devices, we typically jump straight to drum machines, rack synths, and keyboard controllers. However, there’s nothing saying you can’t build your own MIDI controllers that use the magic of breath to do their musical duty. That’s precisely what [Xavier Dumont] did with this unique 3D printed build.

The device looks somewhat like an alien ship from an animated 1960s sci-fi movie, but it’s actually a sophisticated MIDI controller. Naturally, it’s peppered with buttons as every good controller should be, and it features a touch-control strip on the back.

However, the real magic is in the breath control. When the user blows into the sensor, the device sends out MIDI signals of varying intensity to control the object of the player’s desire. The breath signal can be used to modulate the mod wheel, pitch bends, or octave shifts, among a variety of other options.

[Xavier] wields the instrument with prowess in the audio demos at the end of the video. We can imagine this futuristic thing being played by a background alien in a celebration scene in a far-flung Marvel movie. Or maybe Star Wars? In any case, a triumph.

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