Line Follower has Lots of recycled Parts, but Zero Brains

Line Followers are a tried-and-true type of robot; both hardware and software need to be doing their job in harmony in order to be successful at a clearly defined physical task. But robots don’t always have microcontrollers and software, as [Mati_DIY]’s zero programming analog line follower demonstrates.

For readers used to seeing a Raspberry Pi or Arduino in almost everything, an analog robot whose “programming” exists only as a harmony between its discrete parts can be an eye-opener as well as an accessible project. A video of the robot in action is embedded below.

[Mati_DIY]’s design uses two CNY70 reflective sensors (which are essentially infrared emitter/phototransistor pairs) and an LM358 dual op-amp. Together, the sensors act as two near-sighted eyes. By using the output of each sensor to drive a motor via a transistor, the presence or absence of the black line is directly and immediately reflected by the motion of the attached motor. The more black the sensor sees, the more the motor turns. Electrically, that’s all that happens; but by attaching the right sensor to the left motor and the left sensor to the right motor, you get a robot that always tries to keep the black line centered under the sensors. Playing with the spacing of the motors and sensors further tweaks the performance.

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Neural Network Composes Music; Says “I’ll be Bach”

[carykh] took a dive into neural networks, training a computer to replicate Baroque music. The results are as interesting as the process he used. Instead of feeding Shakespeare (for example) to a neural network and marveling at how Shakespeare-y the text output looks, the process converts Bach’s music into a text format and feeds that to the neural network. There is one character for each key on the piano, making for an 88 character alphabet used during the training. The neural net then runs wild and the results are turned back to audio to see (or hear as it were) how much the output sounds like Bach.

The video embedded below starts with a bit of a skit but hang in there because once you hit the 90 second mark things get interesting. Those lacking patience can just skip to the demo; hear original Bach followed by early results (4:14) and compare to the results of a full day of training (11:36) on Bach with some Mozart mixed in for variety. For a system completely ignorant of any bigger-picture concepts such as melody, the results are not only recognizable as music but can even be pleasant to listen to.

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A Wordsearch Twist on the Word Clock

We love seeing new takes on existing ideas, and [Danny] certainly took the word clock concept in an unusual direction with his Wordsearch Clock. Instead of lighting up words to spell out the time, [Danny] decided to embrace the fact that the apparent jumble of letters on the clock face resembles a word search puzzle.

In a word search puzzle, words can be found spelled forward or backward with letters lined up horizontally, diagonally, or vertically. All that matters is that the correct letters are in a line and sequentially adjacent to one another. [Danny]’s clock lights up the correct letters and words one after the other, just as if it were solving a word search puzzle for words that just happen to tell the correct time. You can see it in action in the video, embedded below.

[Danny] went the extra mile in the planning phase. After using a word search puzzle generator tool to assist in designing the layout, he wrote a Processing sketch to simulate the clock’s operation. Visually simulating the clock allowed him to make tweaks to the layout, identify edge cases to address, and gain insight into the whole process. If you’re interested in making your own, there is a GitHub repository for the project.

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Flappy Bird is the New “Does it Run Doom?”

Back in 2014 [Johan] decided to celebrate BASIC’s 30 50 year anniversary by writing his own BASIC interpreter. Now, a few years later, he says he feels he has hit a certain milestone: he can play Flappy Bird, written in his own version of BASIC, running on his own home-built computer, the BASIC-1.

Inside the BASIC-1 is an Atmel XMega128A4, a keyboard from a broken Commodore 64, a joystick port, a serial to TV out adapter, and an SD card adapter for program storage. An attractively laser-cut enclosure with kerf bends houses the keyboard and hardware. The BASIC-1 boots into BASIC just like many of its home computer counterparts from the 80s.

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DIY Barrel Rifling with 3D Printed Help

[Jeff Rodriguez] has been busy testing a feasible DIY method for rifling a barrel and has found some success using salt water, a power supply, wire, and 3D printed parts to create the grooves of rifling without the need for any moving parts or cutting tools. Salt water flows between the barrel’s inside surface and a 3D-printed piece that holds wires in a precise pattern. A current flows between the barrel and the wires (which do not actually touch the inside of the barrel) and material is eroded away as a result. 10-15 minutes later there are some promising looking grooves in the test piece thanks to his DIY process.

Rifled barrels have been common since at least the 19th century (although it was certainly an intensive process) and it still remains a job best left to industrial settings; anyone who needs a barrel today normally just purchases a rifled barrel blank from a manufacturer. No one makes their own unless they want to for some reason, but that’s exactly where [Jeff] is coming from. The process looks messy, but [Jeff] has had a lot of space to experiment with a variety of different methods to get different results.

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This Art Project’s Video is Not a Time-Lapse


Artist Pe Lang uses linear polarization filters to create an unusual effect in his piece polarization | nº 1. The piece consists of a large number of discs made from polarizing film that partially overlap each other at the edges. Motors turn these discs slowly, and in the process the overlapping portions go from clear to opaque black and back again.

The disc rotation speed may be low but the individual transitions occur quite abruptly. Seeing a large number of the individual discs transitioning in a chaotic pattern — but at a steady rate — is a strange visual effect. About 30 seconds into the video there is a close up, and you can see for yourself that the motors and discs are all moving at a constant rate. Even so, it’s hard to shake the feeling of that one is watching a time-lapse. See for yourself in the video, embedded below.

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iPad Tossed Out for RetroPie Arcade Cabinet Redux

The naming and remixing in this project can get a little confusing to those unfamiliar with the different elements involved, but what [John Gerrard] has done is take a stylish mini arcade cabinet intended as a fancy peripheral for an iPad and turned it into an iPad-free retro arcade gaming cabinet. He also designed his own power controller for graceful startup and shutdown.

The project started with a peripheral called the iCade (originally conceived as a fake product for April Fool’s) and [John] observed it had good remix potential for use as a mini retro gaming cabinet. It was a good starting point: inexpensively purchased off eBay with suitable arcade-style joystick and buttons, a nice layout, and plenty of hacking potential. With a small variety of hardware from familiar sources like eBay and Aliexpress, [John] rounded up most of what he needed.

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