I’ve Got Two Turntables And A Laser Engraver

November 27, 2022 by Bryan Cockfield 29 Comments

Digital media provides us with a lot of advantages. For something like recording and playing back music, digital copies don’t degrade, they can have arbitrarily high quality, and they can be played in a number of different ways including through digital streaming services. That being said, a number of people don’t feel like the digital experience is as faithful to the original sound as it could be and opt for analog methods instead. Creating analog copies of music is a much tougher matter though, as [Marco] demonstrates by using a laser engraver to produce vinyl records.

[Marco] started this month-long project by assembling and calibrating the laser engraver. It has fine enough resolution to encode analog data onto a piece of vinyl, but he had to create the software. The first step was to generate the audio sample, then process it through a filter to remove some of the unwanted frequencies. From there, the waveform gets made into a spiral, accounting for the changing speed of the needle on the record as it moves to the center. Then the data is finally ready to be sent to the laser engraver.

[Marco] did practice a few times using wood with excellent success before moving on to vinyl, and after some calibration of the laser engraver he has a nearly flawless 45 rpm record ready to hit the turntable. It’s an excellent watch if not for anything than seeing a working wood record. We’ve actually seen a similar project before (without the wood prototyping), and one to play records from an image, but it’s been quite a while.

Thanks to [ZioTibia81] for the tip!

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A Practical Discrete 386

November 27, 2022 by Jenny List 36 Comments

There are some chips that no matter how much the industry moves away from them still remain, exerting a hold decades after the ranges they once sat alongside have left the building. Such a chip is the 386, not the 80386 microprocessor you were expecting but the LM386, a small 8-pin DIP audio amplifier that’s as old as the Ark. the ‘386 can still be found in places where a small loudspeaker needs to be powered from a battery. SolderSmoke listener [Dave] undertook an interesting exercise with the LM386, reproducing it from discrete components. It’s a handy small discrete audio amplifier if you want one, but it’s also an interesting exercise in understanding analogue circuits even if you don’t work with them every day.

A basic circuit can be found in the LM386 data sheet (PDF), but as is always the case with such things it contains some simplifications. The discrete circuit has a few differences in the biasing arrangements particularly when it comes to replacing a pair of diodes with a transistor, and to make up for not being on the same chip it requires that the biasing transistors must be thermally coupled. Circuit configurations such as this one were once commonplace but have been replaced first by linear ICs such as the LM386 and more recently by IC-based switching amplifiers. It’s thus instructive to take a look at it and gain some understanding. If you’d like to know more, it’s a chip we’ve covered in detail.

Portable Commodore 64 Lives!

November 27, 2022 by Al Williams 17 Comments

When you think of a luggable computer, you might think of the old Compaq or — if you are old enough — a Kaypro. But you don’t see as many Commodore SX-64 computers. [The 8-Bit Guy] has wanted one for a while and finally got one, but it wasn’t working. No problem! Just fix it!

The device actually looks sleek compared to some other portables of the era and had a color screen, but — probably due to the price — they didn’t sell very well. The outside of the device looked pretty clean other than some loose screws and clips. The space key was quite yellow but at least there was a keyboard cable which is nearly impossible to find anymore.

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Human Vs. AI Drone Racing At The University Of Zurich

November 26, 2022 by Joseph Long 12 Comments

[Thomas Bitmatta] and two other champion drone pilots visited the Robotics and Perception Group at the University of Zurich. The human pilots accepting the challenge to race drones against Artificial Intelligence “pilots” from the UZH research group.

The human pilots took on two different types of AI challengers. The first type leverages 36 tracking cameras positioned above the flight arena. Each camera captures 400 frames per second of video. The AI-piloted drone is fitted with at least four tracking markers that can be identified in the captured video frames. The captured video is fed into a computer vision and navigation system that analyzes the video to compute flight commands. The flight commands are then transmitted to the drone over the same wireless control channel that would be used by a human pilot’s remote controller.

The second type of AI pilot utilizes an onboard camera and autonomous machine vision processing. The “vision drone” is designed to leverage visual perception from the camera with little or no assistance from external computational power.

Ultimately, the human pilots were victorious over both types AI pilots. The AI systems do not (yet) robustly accommodate unexpected deviation from optimal conditions. Small variations in operating conditions often lead to mistakes and fatal crashes for the AI pilots.

Both of the AI pilot systems utilize some of the latest research in machine learning and neural networking to learn how to fly a given track. The systems train for a track using a combination of simulated environments and real-world flight deployments. In their final hours together, the university research team invited the human pilots to set up a new course for a final race. In less than two hours, the AI system trained to fly the new course. In the resulting real-world flight of the AI drone, its performance was quite impressive and shows great promise for the future of autonomous flight. We’re betting on the bots before long.

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A two picture montage of the blackout logger, the left picture being the front e-ink display of the data logger in a black case and the second picture of the back of the data logger, with the raspberry pi pico show attached to an e-ink display, both sitting on a wooden table.

Blackout Logger Keeps Track Of Power Outages

November 26, 2022 by Abe Connelly 7 Comments

[Dmytro Panin] lives in Kyiv, Ukraine where there have been rolling blackouts to stabilize the power grid. To help keep track of when the blackouts might happen, be they planned or emergency, and to get more information on how long the blackouts last, [Dmytro] has created a blackout logger.

The build consists of a Raspberry Pi Pico that connects to a DS3231 real time clock (RTC) with a Waveshare 3.7 inch eInk display which [Dmytro] puts into a custom 3D printed case. The RTC has it’s own small power supply, often times from a coin cell battery attached to the module, allowing it to keep time when the module and other devices attached to it are powered off.

The Raspberry Pi Pico is programmed to “poll” every 30 seconds, writing the current time to a file. Should the unit lose power, the last time, within a 30 second window, is available when power is restored and the unit wakes up again. Since the RTC has kept the current time, there is enough information to display the duration of the blackout. The eInk screen ensures that the information is readily available, even when there is no power.

War is not the only reason blackouts can occur and we’ve covered some issues with blackouts in Texas and California in the US.

Turn Your Furniture Into A Light Show With Hyelicht

November 26, 2022 by Tom Nardi 18 Comments

There’s something about the regimented square shapes of the IKEA Kallax shelf that convinced [Eike Hein] it could benefit from some RGB LED lighting, and while he could have simply used a commercial solution, he decided instead to develop Hyelicht: an incredibly well documented open source lighting system featuring multiple control interfaces and APIs. We’d say it was overkill, but truth be told, we dream of a world where everyone takes their personal projects to this level.

In the boilerplate configuration, [Eike] shows off controlling the LEDs using a graphical user interface running on a Waveshare 7″ touch screen mounted to the side of the shelf. That’s the most direct way of controlling the LEDs, as the touch screen is plugged into the Raspberry Pi 4B that’s actually running the software. But the same interface can also be remotely accessed by your smartphone or desktop.

You can also skip the GUI entirely and control the LEDs with a command line interface, or maybe poke Hyelicht’s HTTP REST interface instead. The system can even integrate with the Philips Hue ecosystem, if you prefer going that route.

The 5×5 Kallax shelf is the project’s official reference hardware, but of course it will work with anything else you might wish to cover with controllable LEDs. We’ve seen similar setups used to light storage bins in the past, but nothing that can even come close to the documentation and customization possibilities offered by Hyelicht. This is definitely a project to keep a close eye on if you’ve got the urge to add a little color to your world.