Arduino Hacks

3040 Articles

SiCK Mechanical Keyboard Is 3D Printed

November 18, 2019 by 25 Comments

We’ve noticed a rash of builds of [ FedorSosnin’s] do-it-yourself 3D-printed mechanical keyboard, SiCK-68 lately. The cost is pretty low — SiCK stands for Super, Inexpensive, Cheap, Keyboard. According to the bill of materials, the original cost about $50. Of course, that doesn’t include the cost of the 3D printer and soldering gear, but who doesn’t have all that already?

The brains behind this is a Teensy that scans the hand-wired key matrix. So the only electronics here are the switches, each with a companion diode, and the Teensy. The EasyAVR software does all the logical work both as firmware and a configuration GUI.

If you look at the many different builds, each has its own character. Yet they look overwhelmingly professional — like something you might buy at a store. This is the kind of project that would have been extremely difficult to pull off a decade ago. You could build the keyboard, of course, but making it look like a finished product was beyond most of us unless we were willing to make enough copies to justify having special tooling made to mold the cases.

PCBs are cheap now and we might be tempted to use one here. There are quite a few methods for using a 3D printer to create a board, so that would be another option. The hand wiring seems like it would be a drag, although manageable. If you need wiring inspiration, we can help.

For ultimate geek cred, combine this with Ploopy.

Rotary Dial Becomes USB Keyboard

November 17, 2019 by 14 Comments

[Max] had a rotary dial from an old telephone and — unsurprisingly — had nothing in particular to do with it. The simple answer? Use an Arduino Leonardo to turn it into a USB keyboard device.

Of course, the Leonardo can easily impersonate a USB keyboard, so that’s the easy part of the project. Interfacing to the dial requires an understanding of how the phone system works.

While today, TouchTone phones are most common, they were quite uncommon for many years. Early phones required you to have an operator connect your circuit to another person’s circuit. Unfortunately for the operators, the system was inherently unscalable and also cost prohibitive.

There were a variety of schemes tried and — supposedly — an undertaker who was angry that the operator was connecting his customers to her husband’s competing mortuary invented the dial telephone.

The details are pretty simple. A typical dial has two contacts. There’s a normally open contact that closes when you spin the dial to any position. It says closed until the spring returns the dial to the home position.

The other contact is normally closed and makes or breaks the phone line. Each time the dial rewinds past a position, the contact opens briefly. Of course, this is a mechanical system, so the software has to debounce the inputs, but that’s easy enough.

If you don’t have access to a dial, you could always print one. Sort of.

Arduino Does Multitouch

November 17, 2019 by 23 Comments

A lot of consumer gadgets use touch sensors now. It is a cheap and reliable way to replace a variety of knobs and switches on everything from headphones to automobiles. However, creating a custom touch controller for a one-off project can be daunting. A recent ACM paper shows how just about any capacitive sensor can work as a multitouch sensor with nothing more than an Arduino although a PC running processing interprets the data for higher-level functions.

The key is that the Arduino excites the grid using PWM and then examines the signal coming out of the grid. Finger poking changes the response quite a bit and the Arduino can sense it using the analog to digital converters onboard. You can find the actual software kit online. The tutorial document is probably more interesting than the ACM paper if you only want to use the kit.

The optimum drive frequency is 10 MHz. The examples rely on harmonics of a lower frequency PWM signal to get there. The analog conversion, of course, isn’t that fast but since your finger touch rate is relatively slow, they treat the signal as an amplitude-modulated input which is very easy to decode.

The sensors can be conductive ink, thread, or copper strips. There are several example applications, including a 3D printed bunny you can pet, a control panel on a sleeve, and an interactive greeting card.

The sensor forms an image and OpenCV detects the actual touch configuration. It appears you can use the raw data from the Arduino, too, but it might be a little harder.

We imagine aluminum foil would work with this technique. If you get to the point of laying out a PCB, this might come in handy.

Music Box Paper-Punching Machine Settles The Score

November 15, 2019 by 11 Comments

As soon as [pashiran] laid eyes on his first hand-cranked music box, he knew he was in love. Then, he started punching the holes for his first ditty. As the repetitive stress of punching heated up his arm, his love cooled a bit. Annealed by the ups and downs of this experience, he decided to design a machine that can punch the holes automatically.

Soon, [pashiran] found his people — a community of music boxers that transform MIDI files to DXF format, which creates coordinates for CAD software. In [pashiran]’s music puncher, an Arduino MEGA takes a DXF file and bubble-sorts the jumble of x-coordinates. The MEGA conducts a trio of two stepper motors and DC motor. One stepper pushes the paper through on the x-axis, and the other moves the puncher head back and forth across the paper scroll as the y-axis. The DC motor moves the punch up and down.

Now, paired with [Martin] of [Wintergatan]’s method for chaining music box paper together, [pashiran] can write a prog-rock-length opus without fear of repetitive stress injury. And since he’s published the STL and INO files, now you can, too. Watch it punch and play 250 notes worth of “See My Vest” “Be Our Guest” after the break.

There’s more than one way to avoid manually punching all those holes. When [Wintergatan] was wrestling this problem, he inspired the hacker community to create a MIDI-to-laser-cut-stencil solution.

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Finally Your Air Drumming Has An Outlet

November 15, 2019 by 8 Comments

Two engineering students are hard at work on this air drum which they hope will help disabled people and people in nursing homes. Though, we think it just looks fun!

Each board is its own module consisting of the electronics and 3D printed cases. The modules each contain an arduino mini, IR sensor, and LEDs. They share power, audio, and communicate with an i2c bus. Two modules are special, one holds the power system and the other a Raspberry Pi. The units can be put together in different configurations. Finally, they are capped with speaker units.

The demo shown in the video, which you can see after the break, looks fun. The response time is pretty fast and it looks like you can measure all sorts of parameters. This can then be translated into different velocities, pitches, and instruments. It’s somewhere between a theremin and a drum kit, very cool.

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This Arduino Keeps Its Eyes On You

November 13, 2019 by 5 Comments

[Will] wanted to build some animatronic eyes that didn’t require high-precision 3D printing. He wound up with a forgiving design that uses an Arduino and six servo motors. You can see the video of the eyes moving around in the video below.

The bill of materials is pretty simple and features an Arduino, a driver board, and a joystick. The 3D printing parts are easy to print with no supports, and will work with PLA. Other than opening up holes there wasn’t much post-processing required, though he did sand the actual eyeballs which sounds painful.

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Simulate City Blocks With Circuit Blocks In A LEGO Box

November 12, 2019 by 4 Comments

Have you ever looked around your city’s layout and thought you could do better? Maybe you’ve always wanted to see how she’d run on nuclear or wind power, or just play around with civic amenities and see how your choices affect the citizens.

[Robbe Nagel] made this physical-digital simulator for a Creative Programming class within an industrial design program. We don’t have all the details, but as [Robbe] explains in the video after the break, each block has a resistor on the bottom, and each cubbyhole has a pair of contacts ready to mate with it. An Arduino nestled safely in the LEGO bunker below reads the different resistance values to determine what block was placed where.

[Robbe] wrote a program that evaluates various layouts and provides statistics for things like population, overall health, education level, pollution, etc. As you can see after the break, these values change as soon as blocks are added or removed. Part of what makes this simulator so cool is that it could be used for serious purposes, or it could be totally gamified.

It’s no secret that we like LEGO, especially as an enclosure material. Dress it up or dress it down, just don’t leave any pieces on the floor.

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