Author Archives: John Baichtal

Making a Coil Gun Without Giant Caps

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Whenever we see a coil gun project on the Internet, it seems to involve a bank of huge capacitors. [miroslavus] took a different approach with his gun–he wanted his project to be built without those monster caps.

It’s powered by quadcopter LiPo batteries, 2x 1400 MaH drone batteries wired up in series and triggering 21SWG copper coils that [miroslavus] created with the help of a custom 3D-printed winding rig he designed. The rigs have ridges to help you lay the coils down neatly, and they also have mounts for photodiodes, ensuring the gun knows when it’s loaded.

When triggered, the  …read more

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Hackaday Prize Entry: Smart Composting System

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Composting serves an important purpose in our society, reusing our food scraps and yard waste to fertilize gardens rather than fill up landfills. Knowing that most people don’t compost, [Darian Johnson] set out to create a Arduino-controlled composting system to make it as simple as possible. It monitors your bin’s moisture, temperature, and gas emissions to ensure it’s properly watered and aerated.

[Darian]’s project combines a MQ4 gas sensor that detects combustible gas, a soil moisture sensor, and a temperature and humidity probe. The nearby water reservoir is monitored by an ultrasonic sensor that keeps track of the water level; …read more

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Hackaday Prize Entry: Robo-Dog Learns to Heel

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[Radu Motisan] is working on a small rover whose primary trick is being able to identify its owner. Robo-Dog is his proof of concept, a rover that uses five ultrasonic sensors to move toward the nearest obstruction. Obviously, this isn’t the same as being able to recognize one person from another, but it’s a start.

The sensors were home-built using ultrasonic capsules soldered into a custom board, with the tube-shaped enclosures made out of PVC pipe. He made an ultrasonic beacon that uses a 556 timer IC to emit 40 KHz pulses so he can get the hang of steering …read more

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Manually-Adjustable Three-Axis Gimbal

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[Tim Good] built a 3-axis gimbal out of 3D-printed and machined pieces, and the resulting design is pretty sweet, with a nice black-on-black look. He machined the flat pieces because they were too long to be printed in his 3D-printer.

The various axes swivel on four bearings each, and each ring features a manual locking mechanism made out of steel stainless pins that immobilize each axis. The gimbal operation itself appears to be manual. That said, [Tim] used 12-wire slip rings to power whatever camera gets mounted on it–it looks like the central enclosure could hold a camera the size …read more

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3DP Enigma Keyboard Improves on the Original

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[Asciimation], who previously created an Enigma Machine wristwatch, decided to go all-in and make a 3D-printed Enigma machine. Not a perfect replica, but rather an improved version that works the same but doesn’t concern itself with historical accuracy. For instance, the current step involves building the keyboard. Rather than trying to re-create the spring-and-pin method of the original, he simply swapped in readily available, double-throw micro switches.

This project has a tremendous amount of fascinating detail. [Asciimation] did his research and it shows; he downloaded blueprints of the original and used hacked digital calipers to precisely measure each rotor’s teeth, …read more

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Mindstorms Soccer Robot Inspired by Real Soccer Robot

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[Bram], a 17-year-old robot fan from the Nertherlands, had an opportunity to watch a RoboCup soccer match played by autonomous robots, and was inspired to create his own Mindstorms version of the robot for a school project.

The robot he created is around 80 cm in diameter and is controlled by four daisy-chained EV bricks. There are nine large motors for controlling the wheels, two more large motors for grabbing the ball, and two medium motors for the ball-shooting mechanism. It uses a Pixycam for ball detection, and it can identify and move toward the ball so long as it’s …read more

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Testing Distance Sensors

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I’m working on a project involving the need to precisely move a tool based on the measured distance to an object. Okay, yeah, it’s a CNC mill. Anyway, I’d heard of time of fight sensors and decided to get one to test out, but also to be thorough I wanted to include other distance sensors as well: a Sharp digital distance sensor as well as a more sophisticated proximity/light sensor. I plugged them all into a breadboard and ran them through their paces, using a frame built from aluminum beams as a way of holding the target materials at a …read more

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Explore Venus with a Strandbeest Rover

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There’s a little problem with sending drones to Venus: it’s too hostile for electronics; the temperature averages 867 °F and the pressure at sea level is 90 atmospheres. The world duration record is 2 hours and 7 minutes, courtesy of Russia’s Venera 13 probe. To tackle the problem, JPL has created a concept for AREE, a mechanical robot designed to survive in that environment.

AREE consists of a Strandbeest configuration of multiple legs with a monster fan propelling it, and one can imagine it creeping over the Venusian landscape. While its propulsion system might be handled by the Strandbeest mechanism, …read more

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Retro DEF CON Badge Made From ’80s Parts

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DEF CON 25’s theme was retro-tech, and [xres0nance] wasn’t kidding around in the retro badge he built for the convention. The badge was mostly built out of actual parts from the ’80s and ’90s, including the perfboard from Radio Shack—even the wire and solder. Of the whole project just the resistors and 555 were modern parts, and that’s only because [xres0nance] ran out of time.

[xres0nance]  delayed working on the badge until his flight, throwing the parts in a box, and staggering to the airport in the midst of a “three-alarm hangover”. He designed the badge on the plane, downloading …read more

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CNC Mill out of a Building Set

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I have some aluminum building-set parts on hand and just got a second rotary tool, so I thought I’d try my hand at making a light-duty CNC mill—maybe carve up some cheap pine or make circuit boards. This post explores some of the early decisions I’m facing as I begin the project.

Of primary importance is the basic format of the mill’s chassis. Gantry configuration or put everything in a box of girders? How will the axes move–belts or racks? How will the Z-axis work, the assembly that lowers the tool onto the material? Finally, once the chassis is complete, …read more

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