The Best Stereo Valve Amp In The World

August 16, 2017 by Jenny List 83 Comments

There are few greater follies in the world of electronics than that of an electronic engineering student who has just discovered the world of hi-fi audio. I was once that electronic engineering student and here follows a tale of one of my follies. One that incidentally taught me a lot about my craft, and I am thankful to say at least did not cost me much money.

Construction more suited to 1962 than 1992.

It must have been some time in the winter of 1991/92, and being immersed in student radio and sound-and-light I was party to an intense hi-fi arms race among the similarly afflicted. Some of my friends had rich parents or jobs on the side and could thus afford shiny amplifiers and the like, but I had neither of those and an elderly Mini to support. My only option therefore was to get creative and build my own. And since the ultimate object of audio desire a quarter century ago was a valve (tube) amp, that was what I decided to tackle.

Nowadays, building a valve amp is a surprisingly straightforward process, as there are many online suppliers who will sell you a kit of parts from the other side of the world. Transformer manufacturers produce readily available products for your HT supply and your audio output matching, so to a certain extent your choice of amp is simply a case of picking your preferred circuit and assembling it. Back then however the world of electronics had extricated itself from the world of valves a couple of decades earlier, so getting your hands on the components was something of a challenge. I cut out the power supply by using a scrap Dymar Electronics instrument enclosure which had built-in HT and heater rails ready to go, but the choice of transformers and high-voltage capacitors was something of a challenge.

Pulling the amplifier out of storage in 2017, I’m going in blind. I remember roughly what I did, but the details have been obscured by decades of other concerns. So in an odd meeting with my barely-adult self, it’s time to take a look at what I made. Where did I get it right, and just how badly did I get it wrong?

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The Latest Hacker Camp Badge Comes From BornHack

August 15, 2017 by Jenny List 9 Comments

If you’re a fan of outdoor hacker camps, or if you’re a SHACamp attendee who’s still coming down from the event high, you may already know about the upcoming BornHack 2017 hacker camp on the Danish island of Bornholm, from the 22nd to the 29th of this month. It’s a smaller camp than many of the others on the calendar, but it makes up for that with a quite reasonable ticket price, a much longer duration, and a location that is a destination in itself.

Today we have news of the BornHack badge announcement, and though the details are a little sketchy it’s safe to say that there should be plenty there to keep attendees occupied. The irregularly-shaped PCB contains a Silicon Labs “Happy Gecko” EFM32 ARM Cortex M0 microcontroller, a 128×64 pixel OLED display, and the usual array of I/O lines. There is no information about its connectivity as it seems the BornHack folks prefer to run a teaser campaign, but we’d be surprised if there wasn’t some kind of wireless module on the reverse.

Barring a transportation miracle it’s unlikely that any of the Hackaday team will be making it to BornHack, but that’s our loss. It may not be one of the larger camps, but it looks to offer no less of the atmosphere you’d expect from a European hacker camp. At the time of writing there are still BornHack tickets to be had, so head on over to their website if you fancy a week at a hacker camp on a Danish island.

A Tiny Sharp MZ-80K That Really Works!

August 14, 2017 by Jenny List 16 Comments

If you were a computer enthusiast in the late 1970s and early 1980s, one of your objects of desire may well have been a Sharp MZ-80K. This was an all-in-one machine from the Japanese electronics giant, and like Commodore’s PET line it included a CRT monitor, full alphanumeric keyboard and cassette tape drive in a smart console.

[Yasushi Enari] is a modeller of miniatures, and while at high school back in 1981 he made a perfect 1/5 scale model of an MZ-80K as an art project. Fast-forward to 2017, and with the help of a Raspberry Pi Zero, a miniature LCD composite video screen, and a Li-Po battery, he’s turned his 1981 model into a functioning computer.

Sadly he was not able to make his tiny 1981 plastic keyboard work, so an external Bluetooth unit is required to perform that function. And he makes no mention of running an MZ-80K emulator on the little machine, either. But the result is a work of art, and an odd collaboration between his adult and teenage self, something we are guessing most readers would be proud to own.

This isn’t the first tiny replica computer we’ve shown you, an Odroid W went into making this tiny Powermac from an American Girl doll’s toy computer.

Thanks [RC2014] for the tip.

Hands On With The SHACamp 2017 Badge

August 14, 2017 by Jenny List 24 Comments

The badge has become one of the defining features of a modern hacker camp, a wearable electronic device that serves as both event computer and platform for some mild software and hardware hacking. Some events have had astoundingly sophisticated badges while others are more simple affairs, and the phenomenon has even spawned an ecosystem of unofficial badges which have nothing to do with the event in question.

The SHACamp 2017 badge is the latest to come the way of a Hackaday writer, and certainly contains enough to be taken as representative of the state of hacker camp badges in 2017. It doesn’t have a star turn like CCCCamp 2015’s software defined radio, instead it’s an extremely handy little computer in its own right.

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From Handheld Bandsaw To Shop Bandsaw

August 14, 2017 by Jenny List 19 Comments

If you grow up around a workshop then the chances are that you’ll have the most respect for saws. Formative years being constantly warned by parents about their risks leave an indelible mark on the nascent maker, and leave them visibly less cavalier on the matter than for example other hackspace members. The fact remains that saws offer some of the most ready opportunities for danger in your workshop. But which are the least hazardous? In the workshop near where this is being written, definitely a bandsaw is far preferable to a circular saw when it comes to finger retention.

[Making Stuff] has a portable bandsaw, contained in effect within a large handheld power tool. He’s put up a video detailing how he modified it to serve as a more conventional vertical or horizontal bandsaw, with the addition of a sturdily built welded tubular frame and table.

The video starts with the removal of the plastic surround to the trigger and hand grip, then proceeds through the various stages of cutting, measuring, drilling, and welding. The pivot point is the crank bearing from a bicycle, and in a slightly overcomplex touch the switch is a solid state relay rather than something conventional. The metal work is well executed, and while the engineering is noting special and most Hackaday readers could do similar, it has the compelling quality of a workshop video in which everything is done right and the results are well presented. You might not make this saw, but if you had one it wouldn’t disappoint you. The full video is below the break.

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A Tale Of Two Raft Races

August 13, 2017 by Jenny List 5 Comments

It’s the height of summer in the Northern Hemisphere, and hackers and makers everywhere are letting their hair down and enjoying the hot weather on the water. By coincidence last weekend there were two very different raft races in the European hackspace community, at the SHACamp2017 gathering in the Netherlands the villages competed in a cardboard raft race, while on the other side of the English Channel the various hackspaces in and around London came together in a raft race using more conventional materials.

Some of the SHA entries needed a little help.

The SHA race came about through the happy confluence of a surplus of disposable cardboard tents, a sunny afternoon, and the inviting waters of the Nuldemauw. The aim of the contest was for hacker camp villages to make it from the bank to the end of the boat dock, a distance of about 100m, in a boat made from cardboard there and then at the camp. Meanwhile the London spaces met at City Road Basin in London with their more robust watercraft for a series of races, the aim of which seems to have been to be the first to get their crew disembarked at the other end of the course. and sitting in a chair on the bank.

Full steam ahead for South London Makerspace. Toby *Spark (CC BY-NC-SA 2.0)

In both races the inventiveness of the entrants showed itself in a wide range of boat designs. As you might expect those craft with a wider beam fared better than the far less stable narrower ones, with capsizes a feature at each location. Clear winners in the Netherlands were a pair of German teenagers in a very stable wide raft, while in London it was South London Makerspace’s catamaran that scooped the crown. There is a video of the London race which we’ve placed below the break.

The hackspace and makerspace spirit is at its strongest when bonds are forged between members of different spaces. Skills and capabilities are shared, collaboration opportunities abound. The sight of a bunch of European makers getting wet might serve more as entertainment than edification, but behind it lies an important facet of hackspace culture. If you’ve not yet been the spaces closest to yours, do so. You never know, one day you might end up on a capsizing raft because of it.

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Reverse Engineering A BLE Service To Control A Light Bulb

August 13, 2017 by Jenny List 18 Comments

So, you buy an Internet of Things light bulb, it’s a fun toy that allows you to bathe your environment in pretty colours at the touch of an app, but eventually you want more. You start to wonder how you might do more with it, and begin to investigate its inner workings. Then to your horror you discover that far from having bought a device with a convenient API for you to use, it has an impenetrable closed protocol that defies easy access.

This was the problem facing [Ayan Pahwa] when he bought a Syska Smartlight Rainbow LED bulb, and discovered that its Bluetooth Low Energy interface used a closed protocol. But instead of giving up, he proceeded to reverse engineer the communication between bulb and app, and his write-up makes for an interesting read that provides a basic primer on some of BLE’s workings for the uninitiated.

BLE allows a device manufacturer to define their own device service specific to their functionality alongside standard ones for common device types. Using a handy Android app from Nordic Semiconductor he was able to identify the services defined for the light bulb, but sadly they lacked any human-readable information to help him as to their purpose. He thus had to sniff BLE packets directly, and lacking dedicated hardware for this task he relied on a developer feature built into Android versions since KitKat, allowing packets to be captured and logged. By analysing the resulting packet files he was able to identify the Texas Instruments chip inside the bulb, and to deduce the sequences required to control its colours. Then he was able to use the Bluez utilities to talk directly to it, and as if by magic, his colours appeared! Take a look at the video we’ve placed below the break.

Many of us may never need to reverse engineer a BLE device. But if we are BLE novices, after reading [Ayan]’s piece we will at least have some idea of its inner workings. And that can only be a positive thing.

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