You’ve Got Mail: Straining The Limits Of Machine And Man

September 5, 2023 by 10 Comments

When we last left this subject, I told you all about Transorma, the first letter-sorting machine in semi-wide use. But before and since Transorma, machines have come about to perform various tasks on jumbled messes of mail — things like distinguishing letters from packages, making sure letters are all facing the same way before cancelling the postage, and the gargantuan task of getting huge piles of mail into the machines in the first place. So let’s dive right in, shall we?

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An automatic laser turret playing with a cat.

Entertain Your Cats Automatically With LazerPaw

September 5, 2023 by 22 Comments

Most of us would agree that kittens are very cute, but require lots of attention in return. What would you do if you adopted three abandoned cats but didn’t have all day to play with them? [Hoani Bryson] solved his problem by building LazerPaw — an autonomous, safe way to let your cats chase lasers.

Having recently tinkered with computer vision in the form of OpenCV, [Hoani] decided he would make a laser turret for his cats to play with. An infrared camera, used so that the LazerPaw works in the dark, is mounted to the laser and the Raspberry Pi. These electronics are then mounted on a servo-based pan/tilt module, which is in turn mounted with two smartphone clamps to the ceiling. That way, when the cats chase the laser, they will be looking away from the beam source. Additionally, if the device is aiming directly at a cat, the laser is turned off. Finally, [Hoani] added some NeoPixels with an Arduino-based controller for extra hacker vibes.

The LazerPaw’s software takes in a 30 FPS stream from a webcam, scales it down for performance, and applies a threshold filter to it. When a black pixel, which is assumed to be a cat, is detected, it “pushes” the camera away from it depending on how close to the laser it is. The effect of this is that every time a cat catches up to the laser, it moves away again. The processed images are also sent to an interactive website for remote cat playtime. Finally, there is also a physical start button so you don’t need WiFi to use it.

Is your cat more of a sunbather than a deadly murder beast? Maybe it’ll like this cat chair that follows the sun.

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Hands-Free Compass Uses Haptic Feedback

September 5, 2023 by 15 Comments

If you’ve never experienced it before, getting turned around on a cloudy day in the woods or getting lost during an event like a snowstorm can be extremely disorienting and stressful — not to mention dangerous. In situations where travel goes outside the beaten path, it’s a good idea to have some survival gear around, including a good compass. But if you need your hands for other things, or simply don’t want to have to stop often to check a compass, you might want to try out something like this belt-mounted haptic feedback compass.

The compass is based around a Raspberry Pi Pico microcontroller and uses a ULN2803a transistor array chip to control a series of motors. The motors are mounted all along a belt using custom 3D printed clips with wires woven to each through the holes in the belt. The firmware running on the belt communicates with an Android app via USB to control each of the motor’s vibration based on the direction the wearer is traveling and their desired heading. With certain patterns, the wearer can get their correct heading based on the vibrations they feel through the belt.

While it does rely on having a functioning phone, a modern smartphone’s built-in compass doesn’t require a signal to work. We would still recommend having a good simple compass in your pack as backup if you’re going to be far off the beaten path, though. There are other ways of navigation besides by compass, map, or GPS too. Have a shot at inertial navigation if you want a challenge.

Thanks to [Peter] for the tip!

A scale model of the International Space Station

This Model Mimics The International Space Station

September 4, 2023 by 6 Comments

It’s not an overstatement to say that the International Space Station (ISS for short) is an amazing feat of engineering, especially considering that it has been going for over two decades. The international collaboration isn’t just for the governments, either, as many images, collected data and even some telemetry have been made available to the public. This telemetry inspired [Bryan Murphy] and his team to create the ISS MIMIC, a 1:100 scale model of the ISS that reflects its space counterpart.

The model, covered by [3D Printing Nerd] after the break, receives telemetry from the real ISS and actually reflects the orientation of the solar panels accordingly! It also uses this entirely public information to show other things like battery charge level, power production, position above the earth and more on a display. An extra detail we appreciated is the LEDs near the solar panels, which are red, blue or white to indicate using battery, charging battery and full battery respectively. The ISS orbits the earth once every 90 minutes, which can be seen by the LEDs changing color as the ISS enters the shadow of the earth, or exits it.

What could you do to make this better you might ask? Make the it open-source of course! The ISS MIMIC is fully open-source and uses common tools like 3D printing with PLA, Raspberry Pis and Arduinos to make it as accessible as possible for education (and hackers). Naturally, the goal of this project is to educate, which is why it’s open-source and aims to teach programming, electronics, mechatronics and problem solving.

Video after the break.
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3D Printed — Um — Hook And Loop Fasteners

September 4, 2023 by 38 Comments

[Teaching Tech’s] latest video discusses “3D printed Velcro.” But as even he admits, Velcro is a trademark, so we think it is more appropriate to talk about hook and loop fasteners. In fact, you can see the good-natured official video about the trademark below [Teaching Tech’s] video. Regardless, his experiments with several 3D-printed Vel… fastener designs are worth watching.

Some of the designs were rather large, like we would have expected. However, some of the designs were fairly small and looked almost like real Velcro. However, since the pattern is not as random as the fabric portions of the real deal, it seems like alignment between parts is more critical when you are joining the two halves.

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Heat Pump Control That Works

September 4, 2023 by 33 Comments

Heat pumps are taking the world by storm, and for good reason. Not only are they many times more efficient than electric heaters, but they can also be used to provide cooling in the summer. Efficiency aside, though, they’re not perfectly designed devices, largely with respect to their climate control abilities especially for split-unit setups. Many of them don’t have remotely located thermostats to monitor temperature in an area, and rely on crude infrared remote controls as the only user interface. Looking to make some improvements to this setup, [Danilo] built a setup more reminiscent of a central HVAC system to control his.

Based on an ESP32 from Adafruit with an integrated TFT display, the device is placed away from the heat pump to more accurately measure room temperature. A humidity sensor is also included, as well as an ambient light sensor to automatically reduce the brightness of the display at night. A large wheel makes it quick and easy to adjust the temperature settings up or down. Armed with an infrared emitter, the device is capable of sending commands to the heat pump to more accurately control the climate of the room than the built-in controls are able to do. It’s also capable of logging data and integrating with various home automation systems.

While the device is optimized for the Mitsubishi heat pumps that [Danilo] has, only a few lines of code need to be changed to get this to work with other brands. This is a welcome improvement for those frustrated with the inaccurate climate controls of their heat pumps, and since it integrates seamlessly into home automation systems could also function in tandem with other backup heat sources, used in cold climates when it’s too cold outside to efficiently run the heat pump. And, if you don’t have a heat pump yet, you can always try and build your own.

Developing A 4,500 RPM Twin-Cylinder Air Engine

September 4, 2023 by 20 Comments

Compressed air isn’t really a practical form of energy storage for headline uses like transport or heating, but it’s a fun thing to tinker with at the small scale. [Tom Stanton] is plenty experienced in that area, having built a series of compressed air engines over the years. His latest effort is capable of running at up to 4,500 RPM, and delivering a full 0.05 horsepower.

Two-cylinder power!

[Tom’s] ultimate goal is to put his new tiny air engine on a small model aircraft. To enable consistent performance, his engine needs a regulator, but off-the-shelf models for industrial use were too hefty for his use. Thus, he set about equipping his engine with a lightweight regulator of his own 3D-printed design.

His latest ball-valve air engine was then designed to run on this lower regulated pressure of approximately 30 psi. It initially proved less efficient than his previous designs, but some engineering analysis revealed the problem. [Tom] does a great job of stepping through his process of understanding how these engines perform, and how he uses these findings to guide his design choices going forward.

It’s also great to see a YouTuber not just building fun things, but taking measurements and doing some real engineering. [Tom’s] air engines keep getting better, and we can’t wait to see where he takes his designs next.

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