Brass screen is soldered together into a large mold for cardboard pulp.

How To Make A Classy, Brassy Cardboard Pulp Mold

November 17, 2021 by Kristina Panos 4 Comments

When we last checked in with prolific prototypist [Eric Strebel], he was perfecting the design of an eco-friendly wireless charger and turning his initial paper prototype into a chipboard version 2.0 that takes manufacturing concerns into consideration. At the end of this second video in a series, [Eric] was printing out the early versions of the form by which he would eventually make a brass screen mold for working with cardboard pulp. You know, the stuff that some egg cartons are made from.

In the video below, it’s time to build the pulp mold by creating three smaller molds and then joining them into one horizontal mold. The result is a single piece that then gets folded up into a charging stand, much like the egg carton. [Eric] is using brass screen here, but says that copper would be a good choice, too.

After cutting the brass with scissors and pounding them flat, he uses the 3D-printed molds from the previous video to press them into the correct shapes. Each of the three pieces needs a frame, which [Eric] makes from more brass screen, then stitches it to the mold piece with loose screen threads before securing the unions with solder.

Since the weight of all the water would likely bend the brass out of shape, [Eric] finished off the mold by soldering on a frame of flat brass strip. Check out this awesome process below, and stay tuned for the next video when [Eric] pulps some cardboard and pumps out some eco-friendly chargers.

Does this look too complicated? You could always skip the whole mesh mold thing and shape your cardboard confetti directly into 3D printed parts.

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This is a MIDI harp that is played by waving your hands in the air over the infrared distance sensors.

Teensy MIDI Air Harp Sounds Huge

November 15, 2021 by Kristina Panos 4 Comments

Some of the coolest sounds come from wild instruments like orchestra strings, fretless basses, and theremins — instruments that aren’t tied down by the constraints of frets and other kinds of note boundaries. [XenonJohn]’s air harp is definitely among this class of music makers, all of which require a certain level of manual finesse to play well.

Although inspired by Jean-Michel Jarre’s laser harp, there are no lasers here. This is a MIDI aetherharp, aka an air harp, and it is played by interrupting the signals from a set of eight infrared distance sensors. These sensors can be played at three different heights for a total of 24 notes, plus there’s a little joystick for doing pitch bends.

Inside the wooden enclosure of this aetherharp is a Teensy 3.5 and eight infrared distance sensors with particularly long ranges. On top is a layer of red acrylic that doesn’t affect the playability, except in bright sunlight. Although you could use most any MIDI software to produce the actual sounds, [XenonJohn] chose VMPK (Virtual MIDI Piano Keyboard). Be sure to check it out in action after the break.

Not dangerous enough for you? Here’s a laser harp that involves a Tesla coil.

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A robot that uses CV to detect villagers in Stardew Valley and display their gift preferences on a screen.

Stardew Valley Preferences Bot Is A Gift To The Player

November 14, 2021 by Kristina Panos 1 Comment

It seems like most narrative games have some kind of drudgery built in. You know, some tedious and repetitious task that you absolutely must do if you want to succeed. In Stardew Valley, that thing is gift giving, which earns you friendship points just like in real life. More important than the giving itself is that each villager has preferences — things they love, like, and hate to receive as gifts. It’s a lot to remember, and most people don’t bother trying and just look it up in the wiki. Well, except for Abigail, who seems to like certain gemstones so much that she must be eating them. She’s hard to forget.

[kutluhan_aktar]’s villager gift preferences bot is a fun and fantastic use of OpenCV. This bot uses a LattePanda Alpha 864s, which is a single-board computer with an Arduino Leonardo built in. It works using template matching, which is basically a game of Where’s Waldo? for computers.

Given a screenshot of each villager in various positions, the LattePanda recognizes them among a given game scene, then does a lookup of their birthday and preferences which the Leonardo prints on a 3.5″ LCD screen. At the same time, it alerts the player with a buzz and big green LED. Be sure to check it out in action after the break.

In Animal Crossing, the drudgery amounts to pressing the A button while catching shooting stars. That’s not a huge problem for a Teensy.

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Chipboard prototype of a wireless phone charger with style.

Prototyping Your Way To Better Prototypes

November 13, 2021 by Kristina Panos 13 Comments

If you’ve ever made a prototype of something before making the “real” one or even the final prototype, you probably already know that hands-on design time can’t be beat. There’s really no substitute for the insight you will glean from having a three-dimensional thing to hold and turn over in your hands for a full assessment. Sometimes you need to prototype an object more than once before investing time, money, and materials into making the final prototype for presentation.

This is [Eric Strebel]’s second video in series about making an eco-friendly wireless phone charger. He made a paper prototype in the first video, and in this follow-up, he refines the idea further and makes a chipboard version of the charger before the final molded paper pulp prototype. The main advantage of the chipboard version is to design the parts so that each one will be easier to pull from its mold in a single piece without any undercuts.

By building the chipboard version first, [Eric] is able to better understand the manufacturing and assembly needs of this particular widget. This way, he can work out the kinks before spending a bunch of time in CAD to create a 3D-printed mold and making the paper pulp prototype itself. He emphasizes that this process is quite different from the 2.5D method of laser-cutting a single piece of chipboard and folding it up into a 3D object like it was a cereal box, which is likely to hide design issues. Be sure to check out the video after the break.

We think this prototype is quite nice-looking, and believe that everything deserves good design. Why should a wireless charger be any different? [Eric] has prototyped in a lot of media, but he seems especially skilled in the art of foam core board. Start with the masterclass and you’ll have a better appreciation for his foam armored vehicle and one of the many ways he smooths out foam parts.

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A functioning model of the Wunderwaffe DG-2 from Call of Duty: Zombies.

DIY Wunderwaffe And Others Make Up This Open-Source Arsenal

November 7, 2021 by Kristina Panos 17 Comments

Unless you stay up all night and have a dozen printers going, it’s probably way too late to make one of these beautiful prop weapons designed by [Andrew] of The Ray Gun Project in time for Halloween. Most of them are from Call of Duty: Zombies, though there is an awesome little disco grenade from Fortnite as well.

All of the projects are fantastic, but we chose to highlight the Wunderwaffe DG-2 from COD: Zombies because, well, vacuum tubes. For those unfamiliar with the ‘waffe’s operation, those vacuum tubes act as ammo magazines. Once they’re empty, you power them down with that big red switch and eject them one at a time with the lever, just like in the game.

Inside is a Feather M0 Express that runs the RGB LEDs and uses a Hall effect sensor to read magnets in the quick-change ammo magazine. You can see how it works in the demo video after the break.

There are BOMs for several of the prop weapons, along with assembly drawings and support forums for anyone who wants to build their own. Don’t feel like gathering all the bits and bobs yourself? [Andrew] is selling hardware packs for the ray gun, but you’ll have to scrounge the parts yourself if you want to build the Wunderwaffle.

Are you a Grinch who wants to keep kids off of your lawn? Scare ’em off with a giant NERF gun.

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‘Tiny Wake-Up Light Is Hugely Bright

November 6, 2021 by Kristina Panos 26 Comments

Let’s face it — waking up is rough no matter what time of year it is. But the darkness of fall and winter makes it so much worse. In the past, [Maarten] has used music with increasing volume, but depending on the setup, it can be dodgy if you want to hear a different song each day and don’t have all your files volume-leveled.

Wake Up Bright is the latest in a line of wake-up widgets [Maarten] has made to help rouse them in the morning. Their write-up covers all ideas they’ve had on the subject over the years, as well as the electronics, firmware, debugging, and all the upgrades made after using it for awhile.

Slowly brightening an LED doesn’t have to be difficult or expensive. [Maarten] originally used an Atmel 90S2313 AVR and later upgraded to an ATtiny 2313, which was easy because the two are pin-compatible. The 2313 outputs PWM, which duty-cycles the LED to create a nice fade-in of white light that is way more gentle than that classic 1980s alarm clock buzz-beep.

Over time, this project went from one IKEA enclosure to another. We really like the newer one, which looks like it was designed for people to hack into a wake-up light.

Our eyes perceive brightness increases logarithmically, but PWM is linear. We can get around this by multiplying the PWM value by some factor every so often, but the problem is that this AVR never learned its multiplication tables. So how, then? [Maarten]’s answer is byte shifting using a 16-bit register — one byte for PWM, and the other as a scratch pad to do logarithmic math. [Maarten] multiplies the 16-bit register by 1/256 every couple of seconds, which results in a logarithmic increase of brightness. It’s calculated for a 15-minute sunrise, which required some experimentation to get right.

Whereas [Maarten] started with a 3 W RGB LED, the current version has three 10 W LEDs and uses a power supply from an old monitor. Daylight Saving Time is coming to an end in the US, and it’s gonna get worse quickly. Lucky for you, this project is completely open source down to the firmware.

You think that 1980s alarm clock buzz-beep is bad? How about some repeated slaps to the face to wake up?

A one-string bass violin made from two washtubs, some plywood, a Louisville Slugger, and some weed whacker line.

Louisville Slugger Puts This Bass On Base

November 6, 2021 by Kristina Panos 2 Comments

One of the most recognizable instruments in both jug band and American folk music has got to be the washtub bass. Also known as gutbuckets, these instruments tend to use an old broom for a neck and usually have a single string.

We would argue that the design of [goaly]’s single-string double gutbucket owes something to the double bass of the violin family as well, with its figure eight shape. On top of those tubs is a plywood soundboard, which is screwed into a series of wood blocks around the lip of the tubs.

For the combination neck and fretboard, [goaly] called up a vintage Louisville Slugger, which is way more interesting than some old broom handle. [goaly] extended the backbone through the body with scrap lengths of 2″x2″, and this spine runs through both tubs and acts as a peg on the bottom. In lieu of a tailpiece, the string is tied to a board that the player secures with their foot.

Although [goaly] experimented with steel cable, clothesline rope, nylon rope, and paracord first, the string is made from weed whacker trimmer line. At the top, the string is attached through the neck — it’s held down with a couple of bent fender washers and pulled taut with a wingnut. We love that [goaly] even fashioned a wooden tool to make it easy to turn the wingnut. And we also love the DIY bridge, which looks like a little person.

There are a couple of ways to make sounds with this thing. Fretting and plucking work, of course, but so does bending the whole thing backward to change the pitch. For a good time, do both. We think it sounds nice and thump-y, and it even makes great percussive sounds on the front and back. Check it out in action after the break.

Don’t have a washtub? A wheelbarrow works too, and it comes with its own stand.

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