The Smartest Air Freshener In The Room

December 16, 2017 by 6 Comments

Many automatic air fresheners are wasteful in that they either ceaselessly spritz the room, and manual ones need to be — well — manually operated. This will not do in an era of smart products, so Instructables user [IgorF2] has put together an air freshener that does more than check if you’re around before freshening things up.

The air freshener uses a NodeMCU LoLin and an MG 995 servomotor, with a NeoPixel ring acting as a status light. Be aware — when the servo is triggered there is a significant spike in current, so be sure you aren’t powering the air freshener from a PC USB port or another device. After modeling the air freshener’s case in Fusion 360 — files available here — [IgorF2] wired the components together and mounted them inside the 3D printed case.

Hardware work completed, [IgorF2] has detailed how to set up the Arduino IDE and ESP8266 support for a first-time-user, as well as adding a few libraries to his sketch. A combination of an Adafruit.IO feed and ITTT — once again, showing the setup steps — handles how the air freshener operates: location detection, time specific spritzing, and after tapping a software button on your phone for those particularly lazy moments.

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Give Workshop Pencils A Flush-Mounted Home

December 15, 2017 by 17 Comments

Pencils and pens are apt to go wandering in a busy workshop if they don’t have a handy storage spot. For most of us a soup can or an old coffee mug does the trick, but for a prettier and more useful holder [Stuff I Made] has a short video demonstrating a storage unit made from an elbow fitting and a scrap piece of plywood. He cuts a plywood disk that is friction-fit into one end of the elbow, then it gets screwed into a wall making an attractively flush-mounted holder in a convenient spot.

With the right joint the bottom of the holder remains accessible, as a 90 degree bend would be no good. With a shallower joint angle, a regular screwdriver can still reach the mounting screw and it’s possible to access the bottom of the holder just in case it needs cleaning or something small falls inside. You can see the process and results in the video embedded below. Not bad for one screw, a spare joint, and a scrap piece of plywood.

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Turning Saw Blades Into Throwing Stars

December 15, 2017 by 12 Comments

The holidays are nearly upon us, and if you haven’t found the perfect gift for the Mall Ninja in your life yet, this latest hack might be just what you’re looking for. On his YouTube channel, [The Nocturnal Alchemist] demonstrates how to make ninja throwing stars (shuriken) out of an old circular saw blade. One could probably argue that a circular saw itself is close enough to throwing star if your only goal is to wreck some stuff in your backyard, but with this method they’ll have that official samurai look.

To start the process, he hits both sides of the circular saw blade with a grinder to smooth out the surface. He then traces the desired star shapes onto the blade, and cuts the blade into pieces so it’s easier to manage. The rough shape of the stars is cut out with an angle grinder, and a belt sander lets him sharpen the edges.

At this point the stars are effectively finished, but if you want something that’s going to look good on the shelf next to the katana you bought online, you need to do some more finish work. He sands both sides of the stars by hand, starting at 80 grit and working all the way up to 1200 grit wet paper. Once sanded, paste wax is rubbed in with a cloth to give it a protective coating.

With the finish work done, all that’s left to do is throw your new shuriken at cans of soda and watermelons as a demonstration of their power. To this end, he has come prepared with a 1,000 FPS camera; so if you’ve ever wanted to see cans of off-brand soda getting exploded with a throwing star, your Mall Ninja friend isn’t the only one about to get a gift.

With circular saw blade shuriken completed, all you’ll need to do to complete your urban samurai transformation is forge yourself a sword, and perfect your run in virtual reality.

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Coin Cell Powered Sea Turtle Research

December 15, 2017 by 18 Comments

Hacking and tinkering are always fun and games, but one just has to appreciate when all efforts are additionally aimed towards doing something good. [Nikos] sets an example by combining his interest in technology with his passion for wildlife conservation by creating a low cost and ultra-low power temperature logger — and he is using a coin cell for it.

As the founder of a sea turtle conservation project in Greece, [Nikos] enjoys building scientific instruments that help him and his team on their mission. With a goal to log the temperature every 10 minutes over a period of at least 180 days, he designed a PCB just big enough to hold a CR2032 coin cell. Fifty of them will eventually be sealed in waterproof enclosures, and buried in the sand for the whole research duration.

Limiting the design to its bare necessities, the rest of the PCB is housing a digital temperature sensor, an SPI EEPROM to hold all the recorded sensor values over those 180 days, and an ATmega328PB clocked by a 32.768kHz crystal. Wondering what to do with all the extra, unused pins of the ATmega, [Nikos] simply routed them to be accessible through pin headers, thus turning the data logger alternatively into a coin cell powered development board.

Assuming your logging interval requirements are significantly lower, you might be thrilled to hear that [Nikos] estimates a theoretical 7+ years an average coin cell could power the data logger in sleep mode, which makes him confident to reach the 180 days goal.

A Robot Arm For Virtual Beer Pong

December 15, 2017 by 2 Comments

Leave it to engineering students to redefine partying. [Hyun], [Justin], and [Daniel] have done exactly that for their final project by building a virtually-controlled robotic arm that plays beer pong.

There are two main parts to this build: a sleeve worn by the user, and the robotic arm itself. The sleeve has IMUs at the elbow and wrist and a PIC32 that calculates their respective angles. The sleeve sends angle data to a second PIC32 where it is translated it into PWM signals and sent to the arm.

There’s a pressure sensor wired sleeve-side that’s worn between forefinger and thumb and functions as a release mechanism. You don’t actually have to fling your forearm forward to get the robot to throw, but you can if you want to. The arm itself is built from three micro servos and mounted for stability. The spoon was a compromise. They tried for a while to mimic fingers, but didn’t have enough time to implement grasping and releasing on top of everything else.

Initially, the team wanted wireless communication between the sleeve and the arm. They got it to work with a pair of XBees, but found that RF was only good for short periods of use. Communication is much smoother over UART, which you can see in the video below.

You don’t have to have a machine shop or even a 3-D printer to build a robot arm. Here’s another bot made from scrap wood whose sole purpose is to dunk tea bags.

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Brute Forcing Passwords With A 3D Printer

December 15, 2017 by 17 Comments

Many of us use a 4 digit pin code to lock our phones. [David Randolph] over at Hak5 has come up a simple way to use a 3D printer to brute force these passwords. Just about every 3D printer out there speaks the same language, G-code. The same language used in CAD and CNC machines for decades.

[David] placed a numeric keypad on the bed of his printer. He then mapped out the height and positions of each key. Once he knew the absolute positions of the keys, it was easy to tell the printer to move to a key, then press and release. He even created a G-code file which would press every one of the 10,000 4 key pin combinations.

A file this large was a bit unwieldy though, so [David] also created a python script which will do the same thing — outputting the G-code and coordinates to brute force any 4 pin keypad. While a printer is quite a bit slower than Hak5’s own USB Rubber Ducky device (which acts as an automated keyboard), it will successfully brute force a password. Although most phones these days do limit the number of password attempts a user gets.

[David] admits this is probably useless in a clandestine/hacking application, but the video is still a great introduction to G-code and using 3D printers for non-printing functions.

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Thermistors And 3D Printing

December 15, 2017 by 24 Comments

I always find it interesting that 3D printers — at least the kind most of us have — are mostly open-loop devices. You tell the head to move four millimeters in the X direction and you assume that the stepper motors will make it so. Because of the mechanics, you can calculate that four millimeters is so many steps and direct the motor to take them. If something prevents that amount of travel you get a failed print. But there is one part of the printer that is part of a closed loop. It is very tiny, very important, but you don’t hear a whole lot about it. The thermistor.

The hot end and the heated bed will both have a temperature sensor that the firmware uses to keep temperatures at least in the ballpark. Depending on the controller it might just do on-and-off “bang-bang” control or it might do something as sophisticated as PID control. But either way, you set the desired temperature and the controller uses feedback from the thermistor to try to keep it there.

If you print with high-temperature materials you might have a thermocouple in your hot end, but most machines use a thermistor. These are usually good to about 300 °C. What got me thinking about this was the installation of an E3D V6 clone hot end into my oldest printer which had a five-year-old hot end in it. I had accumulated a variety of clone parts and had no idea what kind of thermistor was in the heat block I was using.

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