Making a PCB – the Jeweller’s way! (Part 1)

Sometimes, having trained as a jeweller is surprisingly useful when it comes to working with electronics. After finally having got my head round the way in which ICs are programmed and used on circuit boards with this handy programmer, I decided that the easiest way to incorporate small-scale electronic components in my jewellery was to make a customised PCB (Printed Circuit Board) – it was time to put the theory into action! Not only would creating custom PCBs save me a whole lot of cash (the components are a fraction of the price of a finished circuit board), but it would also allow me to fully control the shape and size of my PCBs.

The first step in this endeavour was creating the circuit design files. Now, there are a number of ways to do this, and which method you use depends largely on your skill base, the complexity of the circuit you want to design and what method you will be using to produce the final board. There are a lot of great freeware packages available online, the most popular probably being the EAGLE PCB software offered by cadsoft. However, I could not get the freeware version to install on my system, and so decided to look for alternatives in the meantime. Fritzing offers a PCB generator as part of its package, but I wanted to use a software that would let me customise tracks and components easily, while offering a library of ‘pre-fab’ parts to play with until I am more familiar with the pin spacing of components and minimum track widths, so after a false start with the very basic FreePCB, in the end I chose the DesignSpark PCB package (v.7.1). Equipped with a full library of parts, as well as a searchable online database of parts offered by UK electronics distributor RS components, this program was really easy to use and before long I had laid down my first PCB design. For the experts out there it is also possible to make PCB layouts in any vector-based graphics software (such as Adobe Illustrator), but of course you will have to be 100% certain of your design as there are no automatic checks or set design rules in a graphics application. DesignSpark has customisable rules and warns you if components are spaced too closely together or if there are missed connections. It is by no means perfect, and I ended up tweaking some of my PCB designs in Illustrator after finalising the layout in DesignSpark to account for crooked or awkward tracks, as well as adding my logos to the boards.

Once I was happy with my designs, I tried to figure out which would be the best way to get them onto the copper covered particle board. After initially considering using the iModela at our MakeSpace, I decided that maybe the old ways are the best and ordered the chemicals required for photoetching. From my time as an undergraduate at ECA I still had some PNP blue resist lying around the studio, and even though some people swear by the slightly more accurate UV-exposure method for transferring your artwork to the resist, if you have a laser printer at home the PNP is easily the most hassle-free solution. After transferring your design to the dull side of the film with a laser printer or photocopier, the film is ironed onto the thoroughly cleaned and de-greased surface of your PCB board. When ironing on the resist, don’t put too much pressure on the iron, as it can spread the ink and make your tracks bleed into each other. There are some great tutorials online about this process, although I would recommend the use of a glassfibre brush (available from enamelling suppliers) for degreasing your board rather than acetone, as it is more reliable and there’s no need for chemicals.

Once you have transferred your artwork to the board, gently peel off the PNP film, and touch up any imperfections or gaps with a black indelible marker pen. In order to preserve the rest of your board, mask off any areas that are not to be etched with brown parcel tape. You should end up with something like this:

First PCB01

The shiny exposed copper areas are going to be etched away, leaving only the black track marks behind. Depending on which chemical you use, prepare as stated on the packaging and fill a small plastic tub with just enough solution to cover your particle board. Gently slide in your board, and agitate the solution roughly every two minutes either with a feather or by gently tipping the tub from side to side. Eventually, all the copper will have been eaten away by the acid, at which point the board needs to be removed quickly from the acid bath with plastic tweezers and rinsed thoroughly under running water. Don’t ever leave your board unattended in the acid, as the acid can undercut the tracks if left too long. Some people have also successfully used the sponge etching method, but I prefer the traditional way as you have a lot less direct contact with the chemicals. After the board has been thoroughly rinsed, you can remove the parcel tape and the resist with acetone.The end result will look similar to this:

First PCB03See how to finish the job in part II…

xCoAx 2015 Glasgow

A few weeks ago I gave a paper at the XcoaX 2015 conference held at the Centre for Contemporary Arts in Glasgow and this year organised and hosted by the University of the West of Scotland. When I initially saw the call for papers in January, I was intrigued by the eclectic mix of themes, encompassing computation, communication, aesthetics, human computer interaction, coding, digital installation art and the ominous ‘X’. When my paper on the aesthetics of creating stimulus-responsive jewellery was accepted, I was really excited to be a part of this diverse conference and could barely wait for the end of June to roll around.

This year the conference consisted of four different events, including an evening of digital performances and the eponymous ‘Algorave’ held at the GSA, in addition to the more traditional paper presentations and an exhibition of works. After a delightful evening reception on the Wednesday, the paper presentations were held over two consecutive days and consisted of five sessions, loosely linked by themes and content. I thoroughly enjoyed all the presentations, and was particularly intrigued by the amount of research focusing on sound related installations. This was a field I had been unaware of before XcoaX, and the idea of ‘live coding’ performances, where programmers write freestyle lines of code to create sound building blocks which in turn are assembled as electronic music is absolutely fascinating. Other highlights included Hanna Schraffenberger and Edwin van der Heide’s Sonically Tangible Objects which provided the audience with a brief glimpse into a future augmented reality, whereas Nicole Koltik’s short paper on philosophies of the artificial and Sofia Romulado’s analysis of videogames as an artform struck a particular chord with me.

On Friday evening we were treated to a string of performances, and Thor Magnusson and Pete Furniss gave a wonderful demonstration of how live coding and traditional instruments can be used to create a completely immersive ‘wall of sound’ experience in their piece Fermata. Another highlight was provided by digital artist Jung In Jung, who had brought dancers Dane Lukic and Stefanos Dimoulas to perform in their interactive sound and dance collaboration Thermospheric Station.

Altogether it was an amazing experience, and one I am hoping to repeat next year when the conference will be held in Bergamot. Better come up with some fresh material by then! I will finish this brief report with images from the exhibition. While all of the works on show were absolutely fascinating (and I finally got to try some real VR goggles!), two in particular struck a chord – Andreas Zingerle and Linda Kronman’s 5-channel interactive audio installation called ‘Let’s talk business’, a humorous installation exploring online scam narratives and Raul Pinto, Paul Atkinson, Joaquim Vieira and Miguel Carvalhais’ growth objects, which use mushroom spawn to create objects based on biological generative systems. See you next year in Bergamot!

Spam 1
Andreas Zingerle and Linda Kronman: ‘Let’s Talk Business’ Installation with Spam can telephones
Mushrooms 1
Pinto, Atkinson, Vieira and Calvahais: ‘Growth Objects – Biological Generative Systems’
Mushroom 2
Detail of a ‘Growth Object’



The Wilderness of Micro Jargon or how I deciphered prototyping langugage

It has been an interesting week here at Smart Central, most of which I spent wrestling with the helpful language used on websites selling components and in their respective datasheets. Even though I have now been trying to get serious about prototyping for more than three years, some instructions given with regards to how to activate certain functions offered by components still baffle and confuse me deeply. So much prior knowledge is just assumed to exist on the part of the creative technologist by the authors of these sites and datasheets, and unless you happen to know someone you can ask what something means exactly, and more importantly how to execute a certain instruction, you run the risk of ruining your components. So I thought I’d write this post about my recent experience with the Adafruit Standalone Toggle Capacitive Touch Sensor breakout.

In theory, this is a beautiful component to use to Toggle Capacitive_1375incorporate a touch sensitive switch into your project – you can even replace the integrated touch pad with a conductive surface to make touch sensitive keys that blend in more discreetly with your project by soldering a connector into the pin below the touch pad. There is a momentary version of this sensor available, which is only active when contact is made, but for my current purpose the on/off toggle function works nicely. Now, because space is at a premium when working on a jewellery scale, even the tiny dimensions of this sensor (about 1.5cm x 2.5cm) were too big for my project and I decided to be daring and simply lop off the redundant integrated touch pad and status indicator LED with a jeweller’s saw. I don’t advocate this as the best way of quite literally ‘hacking’ a component, but in this case I felt the value of the learning experience outweighed the risk of ruining the sensor (I bought a spare just in case). However, much to my surprise the maimed component still worked perfectly afterwards – I made an educated guess about the connections I was savaging, and it seems to have paid off. Great – so far so good!

The next step is where things really started to unravel for me – I wanted to make use of the automatic timer function the sensor had to offer. I had read the following instructions in the Adafruit guide for this part (which covers all their touch sensors but none in greater depth):

It also supports a configurable time-out to turn off the output automatically after a delay. To select this mode, cut the ‘TIMER’ jumper and connect a resistor & capacitor to the TIME pin. For a circuit diagram and resistor/capacitor calculations, see page 13 of the datasheet.

You can also just connect TIME to Vdd and the chip will turn off approx 15 minutes after being turned on. Connect TIME to OUT and the chip will time-out approx one hour after being turned on.

Wow. There are a lot of assumptions of prior knowledge in that paragraph. What is the ‘Timer’ jumper (or indeed a jumper)? How do you cut it? Does the second part of the paragraph about the pre-programmed time-out function also require the jumper to be cut? Do you have to add a resistor/capacitor in that case? I decided to look at the datasheet to gain clarity. Unfortunately, the datasheet is not for the actual breakout board, but for the processor used on the breakout. It is highly technical. It did not address any of my questions, as it is clearly written for a highly specialised audience of electromechanical engineers, who know exactly what they’re doing. I was just about able to decipher some of the instructions relating to the timer function, but what I really needed was the map of the different connections and resistors used on the breakout board, also known as an eagle schematic. These I found tacked on at the very end of the guide thankfully, and soon things started to become clearer. Let’s take a look at the back of the board to start with.

A ‘jumper’ I found out after much googling, is a short length of conductor used to close a break in or open, or bypass part of, an electrical circuit. This can be either a separate component, a simple wire or a printed trace on a PCB. In this case it turned out to be the latter – the toggle breakout indeed has two jumpers, one for the timer function and another for the LED indicator of the integrated touch pad (hacked off in my case):Adafruit Toggle 1375 Back modifiedTo ‘cut’ the timer jumper, I discovered, means simply to use a sharp scalpel and scrape away the small bridge between the two larger pads:Timer CutThis, according to the eagle schematic, changes the state of the timer pinout to ‘high’ (or active) by removing its connection to ground (which rendered it ‘low’ or inactive). It is apparently possible to undo this change by connecting the two pads with a blob of solder, but I haven’t tried this as of yet. It is then merely a matter of soldering a wire between the TIME pin and either the VDD pin (15 min auto turn-off) or GND pin (60 min auto turn-off). You can also set the auto turn-off to any interval you like, by adding resistors and capacitors of the appropriate value as specified on the datasheet, but for me 60 minutes will be just fine.

This may seem like a lot of work merely to figure out a single component, but in the process I have also demystified the language used in PCB instructions and gained more knowledge, which is always a good thing…until the next time!

Tiny little Arduinos…

So, in my quest to create fabulous wearable futures for jewellery lovers, I have come to a point where I have to bite the bullet and get deeply involved in the microelectronics side of my research. The arrival of the Ultimaker has pushed my material experimentation to a whole new level, and the moment has finally come to start creating first assemblies of both materials and electronic components for my symbiotic jewellery objects.

Since I started my research, a lot has happened in the world of wearable computing – particularly in terms of miniaturisation, but also to some extent functionality. There seems to be more of an appetite now for developers to release ever-smaller processors and exciting sensors to the hacker community, and more and more people are starting to use them. For someone like me who is just starting out with electronics (and even after extensive reading and research around the subject for the last three years I would still consider myself a beginner) this is a blessing, as a larger user base means more community support in the shape of blogs, forums and user guides. The Adafruit website has a humungous database of learning projects, starting from scratch with the very basics and ranging all the way to the sublime. Another great resource for getting started is the Sparkfun website, which has a great learning section as well as a user forum. If you live in the States either one of these are very handy for you – just choose a project and order the components to go with it directly from the supplier. In the UK, you have to go through third party retailers, but between them they usually have the full range of components available (including some more from other brands).

In my latest efforts to intergrate electronics into jewellery, I was delighted to find that since I last looked in 2013, not one but five new Arduino-based microcontroller boards had been developed in an appropriate size range for wearables. Brilliant News!…Now which one to choose??? For a previous project, I had dipped my toes into using the Arduino Pro Mini 328 5V and 3.3V boards, which are a great little option if you need a lot of output pins and a reset button. I still have two of those in the workshop, and I am sure they will come to be used in the near future for one of my larger, more elaborate pieces. But they are rectangular in shape, and a bit awkward to use within the more rounded, organic shapes I have been making of late. Also they are quite possibly processing overkill for what I am trying to (and capable of) do in terms of programming. They have a similar functionality to the much larger Arduino Uno, which is definitely a lot more than I need at this point, although I like using one for running prototype programs and test the wired connections.

An immediately appealing option for using in my projects were the Adafruit Flora and Gemma, with the latter being smaller, with fewer pins and no serial monitor capability. They are both circular, which is a much easier shape for me to incorporate than the usual rectangular geometries of PCBs. I ordered the Gemma (the Flora is probably a little bigger than I would like for my use), and it is a nearly perfect size for most of my jewellery projects, with the handy JST and USB mini jacks meaning programming and powering the controller is a doddle. However, I am as of yet struggling with the programming – the first example sketch  I tried to load onto it would not work (and we’re not talking Blink here btw), because of the lack of a serial monitor. I have not given up on Gemma, but I might have to postpone until my programming knowledge catches up. Another small controller recently introduced by Adafruit is the Trinket, which I have not yet had a chance to consider, but which is supposed to have the processing power of an Arduino Uno and looks really really neat and tiny…

…Which brings us to the last two new arrivals to the wearable controller market of late, the TinyDuino and TinyLily. Born out of a Kickstarter campaign by developers TinyCircuits,  these are whole systems of tiny microcontrollers and accessories. Essentially built around the hardware of the Arduino Pro Mini and LilyPad series, the TinyDuino is square in shape and comes with an array of development boards and accessories, while the TinyLily is round and merely the size of my thumbnail but still has 8 sewable ports (4 analogue/4 digital) and two power outlets to play with – plenty for my requirements. The input voltage on these two controllers is variable between 2.7V and 5.5V, so allows for use with a large range of sensors and devices. Here is a size comparison of the Flora, Gemma and TinyLily for reference:

Size Comparison TinyLilyWhile the TinyLily is slightly more awkward to program and connect, it has a definite size advantage over the other two that for making digital jewellery could make all the difference. It is slightly more expensive than the Gemma and about half the price of the Flora, but that seems about right in terms of functionality and processing power. Just for comparison, here are the Trinket, Trinket Pro and Arduino Pro Mini Boards:

Size Comparison Trinket

Sizewise they are perfectly suitable for wearables, especially if you need the advanced functionality and processing power – with Adafruit Neopixels for instance. Their rectangular shape makes them a bit awkward for me, but I could see how they would work in the right situation. Now, on to tackling the programming…