A Pi Powered Recording Studio

March 13, 2016 by 48 Comments

In the mid-90s, you recorded your band’s demo on a Tascam cassette tape deck. These surprisingly cheap four-track portable studios were just low tech enough to lend an air of authenticity to a band that calls itself, ‘something like Pearl Jam, but with a piano’. These tape decks disappeared a decade later, just like your dreams of being a rock star, replaced with portable digital recording studios.

The Raspberry Pi exists, the Linux audio stack is in much better shape than it was ten years ago, and now it’s possible to build your own standalone recording studio. That’s exactly what [Daniel] is doing for our Raspberry Pi Zero contest, and somewhat predictably he’s calling it the piStudio.

Although the technology has moved from cassette tapes to CompactFlash cards to hard drives, the design of these four-track mini recording studios hasn’t really changed since their introduction in the 1980s. There are four channels, each with a fader, balance, EQ, and a line in and XLR jack. There are master controls, a few VU meters, and if the technology is digital, a pair of MIDI jacks. Since [Daniel] is using a Raspberry Pi for this project, he threw in an LCD for a great user interface.

As with all digital recorders, the money is in the analog to digital converters. [Daniel] is using a 24-bit, 216kHz, four-channel chip, Texas Instruments’ PCM4204. That’s more than enough to confuse the ears of an audiophile, although that much data will require a hard drive. Good thing there will be SATA.

Although you can buy an eight-channel solid state recorder for a few hundred dollars – and [Daniel] will assuredly put more than that into this project, it’s a great application of a ubiquitous Linux computer for a device that’s very, very useful.

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Blinky LED Bike Bag

March 13, 2016 by 20 Comments

Bicycle riders can never be too visible: the more visible you are, the less chance there is someone will hit you. That’s the idea behind the Arduibag, a neat open-source project from [Michaël D’Auria] and [Stéphane De Graeve]. The project combines a joystick that mounts on the handlebars with a dot matrix LED display in a backpack. By moving the joystick, the user can indicate things such as that they are turning, stopping, say thank you or show a hazard triangle to warn of an accident.

The whole project is built from simple components, such as an Adafruit LED matrix and a Bluno (an Arduino-compatible board with built-in Bluetooth 4.0) combined with a big battery that drives the LED matrix. This connects to the joystick, which is in a 3D printed case that clips onto the handlebars for easy use. It looks like a fairly simple build, with the larger components being mounted on a board that fits into the backpack and holds everything in place. You then add a clear plastic cover to part of the backpack over the LED matrix, and you are ready to hit the road, hopefully without actually hitting the road.

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Machine Shop Soaps Are Good, Clean Learning Fun

March 13, 2016 by 31 Comments

At first glance, it’s easy to dismiss the creation of custom bath soaps as far outside the usual Hackaday subject matter, and we fully expect a torrent of “not a hack” derision in the comments. But to be able to build something from nothing, a hacker needs to be able to learn something from nothing, and there is plenty to learn from this hack.

On the face of it, [Gord] is just making kitschy custom bath soaps for branding and promotion. Cool soaps, to be sure, and the drop or two of motor oil and cutting fluid added to each batch give them a little machine shop flair. [Gord] experimented with different dyes and additives over multiple batches to come up with a soap that looked like machined aluminum; it turns out, though, that adding actual aluminum to a mixture containing lye is not a good idea. Inadvertent chemical reactions excepted, [Gord]’s soaps and custom wrappers came out great.

So where’s the hack? In stepping way outside his comfort zone of machining and metalwork, [Gord] exposed himself to new materials, new techniques, and new failure modes. He taught himself the basics of mold making and casting, how to deal with ultra-soft materials, the chemistry of the soap-making process, working out packaging and labeling issues, and how to deal with the problems that come from scaling up from prototype to production. It may have been “just soap”, but hacks favor the prepared mind.

Birthday Celebrations The Pi Way

March 13, 2016 by 3 Comments
The William Gates Building concourse packed with Pi enthusiasts
The William Gates Building concourse packed with Pi enthusiasts

On a damp and cold Saturday in early March the Cambridge University Computer Laboratory threw open its doors to the Raspberry Pi community. The previous Monday had been the fourth (or first, if you are a leap year pedant!) birthday of the little single-board computer, and last weekend saw its official birthday celebration.

The festivities took the form of an exhibition floor with both traders and community show-and-tell exhibits, plus a packed schedule of workshops and talks. With the Raspberry Pi 3 launch only a few days before there were no surprise announcements of exciting new hardware, but it did provide a good networking opportunity for the Pi community and a chance to test the state of the Raspberry Pi nation.

The most obvious first impression at the event was that it was one that catered for a diverse range of ages and ability groups. Side-by-side with parents and their children were educators, and the maker community. The range of exhibits was therefore slanted somewhat towards a younger age range with games and interactive exhibits, and there was more than a slight educational flavour to the event. This was entirely in keeping with the Foundation’s objectives, and since it is events like these that are inspiring the Hackaday readers of the next decade, a very welcome sight. Join us after the break for a look at all that was happening at the event.

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Designing A Crystal Ladder Bandpass Filter

March 13, 2016 by 18 Comments

Most hobbyists use crystals as an external clock signal for a microcontroller. A less common use would be to make a bandpass filter (BPF) for an RF signal. [Dan Watson] explains his crystal ladder design on his blog and links to several sources for understanding the theory and creating your own crystal ladder band pass filter. If you want a set of these purple PCBs you can order them straight from the purple fab.

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[Dan]’s schematic
One of the sources that [Dan] cites is [Larry Benko]’s personal site which is primarily dedicated to amateur radio projects. Which you can find much more in-depth information regarding the design of a xtal BPF. [Larry] goes into detail about the software he uses and some of the applications of crystal ladder filters.

BPF designed by [Larry]
BPF designed by [Larry]
The process includes measuring individual xtals to determine which ones will work together for your target frequency. [Larry] also walks you through the software simulation process using LTSpice. If you aren’t familiar with Spice simulation you can get caught up by checking out the series of Spice articles by our very own [Al Williams].

Thanks to Dangerous Prototypes for the tip.

Upcycle Old Speakers With C.H.I.P.

March 12, 2016 by 18 Comments

Sometimes you get a piece of hardware that’s so cool you can’t help but fix it back up. There are a lot of companies after that sweet, sweet Raspberry Pi money, and the $9 US Dollar C.H.I.P. is a very interesting contender for the space. We have been especially enjoying the stream of neat hacks and example projects they’ve been putting out.

In this case, [Peter] wanted to get a pair of walnut speakers up to modern standards. Already suffering from a glut of audio equipment in his personal space, he decided to sweeten the deal by adding support for his library of music.

The first step was ordering a new set of drivers to replace the aged 40-year-old ones occupying the set. After he got them installed, he added C.H.I.P., a power supply, an amplifier, and a 500GB hard-drive. The controlling software behind the installation is the venerable mpd. This way he can control the speakers from any device in his house as long as he had an interface installed for the daemon.

We’re glad these speakers didn’t end up in the garbage behind a goodwill somewhere, and they do look good.

How Many LEDs Are Too Many?

March 12, 2016 by 23 Comments

“Should you answer a rhetorical question?” But anyway, the answer is that you can never have enough LEDs. At least that’s what [Adam Haile] at maniacallabs seems to think. So far, he’s up to 3,072.

We’ve reported on a previous big-LED build of [Adam]’s before, called the “Colossus”. And while this current display is physically smaller, it’s got a lot more LEDs. And that means a lot more, well, everything else. Weighing in at roughly 500W when full-on, with 175-part 3D printed frame and diffuser elements and driven by three Teensy 3.2 microcontrollers driving shift registers, this display is capable of putting out 60 frames per second of blinding RGB LED goodness.

The designs, adapter boards, and animation code will be posted once they’ve “had a chance to clean things up a little”. Here’s hoping that’s soon! [Edit: Code and designs are here. Thanks Adam!]

If you’re in the greater Washington DC area, you can even swing by the NoVA Maker Faire in Reston to check it out in person. If you do, tell ’em Hackaday sent you.

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