A Robotic 808 Drum Machine

September 18, 2016 by Jenny List 14 Comments

If you spent the 1980s hanging out at your local record store, and you don’t have a hankering for spandex and bouffant rock-god hairstyles, the chances are you’ll have more than a few pieces of electronic music from the period in your collection. The proliferation of electronica during that era came through the arrival of relatively inexpensive mass-market digital polyphonic instruments, edging out the sounds of monophonic analog synthesisers for a subsequent generation to rediscover in a later decade. Individual instrument models became icons and entered the musical vernacular of the day, the Ensoniq Mirage sampling synthesiser, the Yamaha DX7 FM synthesiser, or the Roland TR-808 drum machine.

It is the Roland TR-808 that inspired today’s subject, the MR-808 robotic drum machine, from [Moritz Simon Geist]. A percussion sequencer featuring real instruments all built into a cabinet styled to resemble a huge Roland 808. Originally built as a performance instrument, but since reinvented as a piece of installation artwork that visitors can program for themselves.

There is a comprehensive description of the machine’s design and build on the creator’s website, as well as a more high-level introduction. A significant amount of effort was put in to creating mechanical instruments as close as possible to the Roland sounds, with each instrument being operated by solenoids driven by a MIDI-controlled Arduino Mega. A second Arduino, this time an Uno, controls lighting that follows the instruments.

The interactive part of the installation comes from a sequencer front-end running in a web browser on a Nexus 7 tablet, this appears to be served from a Raspberry Pi which supplies MIDI to the MR-808.

The results can be seen in the video below the break, and judging by the reaction of the audience the machine is rather popular.

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Clustering A Lot Of Raspberry Pi Zeros

September 18, 2016 by Jenny List 57 Comments

It became something of a cliché a few years ago in online discussions, whenever a new single board computer was mentioned someone would pop up and say something like “Imagine a Beowulf cluster…“. Back then it was said largely in jest, but with the current generation of boards it’s a distinct possibility. Who hasn’t looked at a Raspberry Pi and idly thought about a cluster of them, or even created one!

[Electronoob] did just that, creating a variety of Raspberry Pi cluster configurations, the most impressive of which is a stack of 32 Pi Zeros mounted together with stand-offs. The plan was to network it via USB, for which he initially considered building a backplane, but was put off by the cost of vertical USB connectors and instead went for a wired approach. If there is a lesson to be learned from his experiences it is that buying very cheap USB cables is a minefield: his pile of eBay specials turned out to have significant numbers of faults. He’s now faced with a stark choice, solder 32 sets of USB pads on the base of each Zero or buy better cables.

The stack of Zeros is pretty impressive, but so what, you think. It’s still not working properly. But the Zero cluster isn’t his only work. He’s also created a set of very nicely executed Ethernet clusters using the larger Pi boards, and the way he’s mounted them on top of compact Ethernet switches sets them apart from some of the more spaghetti-like Pi clusters.

It’s true a Pi cluster won’t cut it in the world of supercomputers, you could almost certainly buy more bang for your buck without too much effort. But it does represent a very accessible way to learn about cluster computing, and you have to admit it a stack of Zeros does look rather impressive.

We’ve seen quite a few Pi clusters here since 2012, the biggest of which is probably this 120 node behemoth, complete with screens.

Vacuum Exposure Unit Gives Better PCB Etching Results

September 18, 2016 by Jenny List 18 Comments

PCB etching seems to be a subject that sharply divides our community into those who are experts in it and etch themselves every PCB they use, and those who have significant quantities of ferric chloride stained clothing in their past and for whom the advent of cheap commercial PCB manufacture and CNC milled PCB prototyping have been the best thing since sliced bread.

Your likely success when etching your own boards is most dependent on the quality of your preparation and your equipment. If you began your PCB career with etch-resist transfers and a permanent marker with a Tupperware tub of etchant, then later progressed to laser toner or photographic masking and a bubble etcher, you’ll understand this.

[Jana Marie Hemsing] has drawn our attention to this very nicely built PCB etching suite (Translation, German original) at the Warpzone hackerspace (Translation, German original) in Münster, Germany. The foil pattern is printed on transparency and exposed to UV light over a photoresist coated board with a vacuum pump arrangement to ensure as good a contact as possible to the board for the sharpest result. They have two exposers, one for single sided and the other for double-sided boards, both are very well-built from what looks like plywood.

The attention to detail continues with a home-made magnetic stirrer and heated bubble etching tank Their etchant of choice is sodium persulphate, so there are none of those brown ferric chloride stains.

PCB etching is nothing new, indeed we have covered the subject extensively over the years. But we think you’ll agree, if you’re going to etch your own PCBs you should have as good a set-up as you can, and Warpzone’s PCB suite is rather well put together. Those of us in spaces with lesser facilities should be getting ideas from it.

Hackaday Prize Entry: AutoFan Saves Tired Drivers With Face Recognition

September 17, 2016 by Jenny List 10 Comments

Long distance driving can be tedious at times. The glare of the sun and the greenhouse effect of all your car’s windows make it hot and dry. You turn on the fan, or air conditioning if you have it, and that brings relief. Soon enough you’ve got another problem, the cold dry air is uncomfortable on your eyes. Eventually as you become more tired, you find yourself needing the air on your face more and more as you stay alert. You thus spend most of the journey fiddling with your vents or adjusting the climate controls. Wouldn’t it be great if the car could do all that for you?

AutoFan is a project from [hanno] that aims to automate this process intelligently. It has a fan with steerable louvres, driven by a Raspberry Pi 2 with attached webcam. The Pi computes the position of the driver’s face, and ensures the air from the fan is directed to one side of it. If it sees the driver’s blink rate increasing it directs the air to their face, having detected that they are becoming tired.

The build logs go into detail on the mathematics of calculating servo angles and correcting for camera lens distortion in OpenCV. They also discuss the Python code used to take advantage of the multicore architecture, and to control the servos. The prototype fan housing can be seen in the video below the break, complete with an unimpressed-looking cat. For those of you interested in the code, he has made it available in a GitHub repository.

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Retrotechtacular: Railroads In The Jet Age

September 16, 2016 by Jenny List 29 Comments

The front of the Soviet jet train on a monument in Tver, Russia. By Eskimozzz [PD], via Wikimedia Commons.

It started with one of those odd links that pop up from time to time on Hacker News: “The strange and now sadly abandoned Soviet Jet Train from the 1970s“. Pictures of a dilapidated railcar with a pair of jet engines in nacelles above its cab, forlorn in a rusty siding in the Russian winter. Reading a little further on the subject revealed a forgotten facet of the rivalry between Russians and Americans at the height of the Cold War, and became an engrossing trawl through Wikipedia entries, rail enthusiast websites, and YouTube videos.

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RC Car Piloting With The Blast Shield Down

September 16, 2016 by Jenny List 26 Comments

Many of us have had a radio controlled car at some time in our youth, though it’s probable that none all of us entirely mastered it. There are memories of spectacular crashes, and if we were really unlucky, further boosts to Mr. Tamiya’s bank balance as fresh parts had to be fitted.

[Paul Yan] was watching his young son with a radio controlled toy, and was struck by how the two-joystick control layout is not necessarily as intuitive as it could be. By contrast when faced with a console game with first-person view and a steering wheel the boy had no problem dropping straight into play. This observation led him to investigate bringing a console steering wheel to an RC car, and the result is a rather impressive FPV immersive driving experience.

Paul's FPV car, explained. — Paul’s FPV car, explained.

His build took a PS2 steering wheel peripheral with pedals and mated it to an Arduino Uno via a PS2 shield. The Uno talks to a Nordic NRF24L01 RF module, which communicates with another NRF24L01 on the car. This in turn talks to a car-mounted Arduino Micro, which controls the car servos and speed controller.

FPV video is provided by a miniature camera and transmitter from the world of multirotor flying which is mounted on the car and transmits its pictures over 5GHz to a set of monitor goggles. Sadly he does not appear to have posted any of the software involved, though we doubt there is anything too challenging should you wish to try it for yourselves.

The video below shows the car in action, complete with an over-enthusiastic acceleration and crash from his young son. He tells us it’s a similar experience to playing a racing kart game in the real world, and having seen the video we wish we could have a go.

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Hackaday Prize Entry: Neopixel Pocket Watch

September 15, 2016 by Jenny List 10 Comments

A timepiece is rather a rite of passage in the world of hardware hacking, and we never cease to be enthralled by the creativity of our community in coming up with new ones.

Today’s example comes from [Joshua Snyder], who has made a pocket watch. Not just any pocket watch, he’s taken the shell of a clockwork watch and inserted a ring of Neopixels, which he drives from an ESP8266 module. Power comes from a small LiPo battery, and he’s cleverly engineered a small push-button switch so that it can be actuated by the knob from the original watch. Different colour LEDs traverse the ring to simulate the hands of a traditional timepiece, and the whole nestles behind the perforated cover of the watch shell for something of a steampunk feel.

He admits the battery life is not very good at the moment, probably because for now the WiFi is always enabled so he can reach its web interface for debugging. Sadly he appears to have not yet posted the software, but he does tell us it uses NTP to update its time, and that it supports over-the-air updating for new versions. He suggests a future version might dispense with the ESP and use an ATtiny or similar with a real-time clock giving better battery life.

We’ve covered a lot of LED timepieces over the years, including quite a few watches. Only a small selection are this PIC LED ring in a pocket watch case, another LED ring this time powered by an ATMega645, and this very stylish OLED wristwatch.