Arduino Meetup

Any recent visitors to my blog might have noticed that it is lacking in recent posts. I want to reassure you that I haven’t lost momentum – just in blogging. I’m not in the habit of recording everything that I do,  although it’s probably a habit I should adopt. In the last few months I’ve made a reubens tube (short-lived – don’t use plastic pipe) and a midi-controlled air siren. Both have unfortunately been demolished to make way for other projects, and I didn’t even think to keep any record of either.

However, I have been working on something that will be here to stay. Back in September a band called Lostrites got in touch with me and asked if I’d be interested in making them a laser harp, either to use on stage or to keep around their studio as a novelty. I was, so I’ve been putting a lot of my spare time recently into putting something a bit more special than my earlier attempts. It’s not finished – but it is (finally) shaping up well.

I’ll be at the Manchester Madlab tomorrow evening presenting the instruments I had at the maker faire earlier this year. You can find out more here. I’ll also be bringing along the newest laser harp, which will unfortunately be for display only. Plenty of little things to fix before it’s useable.

Thanks go to James Medd ( and Mike Stephens ( for inviting me along to speak – it’s not something I have a lot of experience of, but you can at least expect to have any questions you might have about my instruments answered, as well as having a go!

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Magic 8 Box

So, among the items I purchased recently from Cool Components was this Red 16×2 LCD Display. I haven’t made anything for a couple of weeks, so I boshed out a Magic 8 Box (or a digital version of the Magic 8 Ball).

Magic 8 Box

Magic 8 Box

This thing contains all 20 original answers from the original Magic 8 Ball, and I’ve added 10 of my own. Its function is pretty straightforward – you just push the button for an answer to your yes/no question. I was pleased to be able to house it all inside the box that the LCD arrived in from cool components.

I’m using an Arduino powered by a 9V battery (although you might notice I’m using USB power above). This is a great beginner’s project, so if you want a copy of the code and a crudely drawn schematic, just contact me.

I’m going to be taking this apart soon, as I intend to use the LCD display in the next version of the laser harp, which will include (hopefully): slightly more responsive note detection (Although it’s already nearly perfect), a paint job, a MIDI reset, a display for showing scale and fundamental note, and maybe even a MIDI setup option, so you can add your own scales to the library via a MIDI in port.

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The Maple

So I recently purchased a few things from Cool Components, one of which was the Leaflabs Maple.

Leaflabs Maple

Leaflabs Maple

This is a development board that is very similar to the Arduino – in fact, one of its aims is to be as similar to the Arduino as possible, while giving a chunk of extra processing power, memory and loads of extra inputs, all on a smaller board! At the Maple’s heart is a 32-bit ARM microprocessor, the same type already used in hundreds of different portable devices. Maple also has its own IDE that is so similar in function and use to the Arduino’s that you can directly copy code between them, and unless you’ve used any chip-specific commands your code will be fine (I’ve tried this, and it worked perfectly). The only drawback I’ve found is that the Maple’s power handling is a little less sturdy than the Arduino’s and I’ll have to be a little more careful to avoid frying it.

I intend to use this board in the next iteration of the tap detector – the increased memory and processing speed is exactly what I need to work out all those FFT’s more accurately, and with less delay.

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Manchester Mini Maker Faire

So, I’ve spent the last two days showing the three midi inputs I’ve made to the general public, and the good news is that two of them are durable and flexible enough to be used for this. The tap detector didn’t fare so well, there being a little too much ambient noise to put it to use. However, I do have plans to improve it and build in noise cancelling algorithms.

I also met and saw a number of other great and talented exhibitors:

James Medd – An artist, maker and musician –

Iain Sharp – Beautiful little custom synths and cycle pong! –

Rodrigo Constanzo – Innovative electronic musician –

The Manchester Hackspace (HAC MAN) – a bunch of electronics geniuses –

The Manchester Girl Geeks – Especially Amy Mather for her Arduino Volcano –

Also, check out the work of Susan Thomason!

Apologies to those not included here – I was impressed by every stall at the maker faire and will certainly be attending events like this again. I also intend to join the Manchester hackspace when I have a free Wednesday evening!

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Laser Harp MkII Video

As promised, I’ve recorded a couple of videos of two of my musical devices in use. Enjoy!

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Another Midi Gizmo – Continued

So, the above device (Arduino powered again) is intended to detect (via a microphone) different kinds of taps on a surface, and convert them into midi messages. It’s intended use is for laying down Midi drum tracks quickly and easily, without the need for expensive V-kits or drum pads. However, there are few problems with it at the moment – it works, but not too well. It may only be about 95% accurate at detecting the difference between two different instantaneous sounds, and that gets worse the more sounds you add to it’s memory. I think the concept is good, but it may need to be realised on something more powerful than an Arduino! I will be bringing it along to the MOSI mini maker fair this week, so if you want to have a go, come on down.

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Another midi gizmo

Just a brief preview of what I’m currently working on – it may not look like much, but this could easily be the most original and entertaining thing I’ve made  yet. It might seem that it’s only an Arduino, some buttons, a microphone and a midi port, but most of the magic happens within the Arduino’s tiny processor.  I’ll elaborate in a later post…

The next project...

The next project…Just a prototype for now.

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Arduino range to midi sensor

Arduino Range to Midi sensor - Long Exposure

Another of the projects I’ve been working on for the maker faire is something a little simpler than the laser harp – a range sensor that converts a detected distance to midi messages. These messages are usually control change messages, used for adjusting different effects and filters in music software, although I have programmed a version that transmits midi notes (which is a little like using a theremin).

Here I’m using the Sharp 2YOAO2 range sensor (available here) and an Arduino. The reason you can see two range sensors was that my initial design involved using two range sensors, although I quickly decided using two was unnecessary, so only one is active.

The LED you can see shining is just to give a visual indication of (approximately) where the sensor’s beam is – which spreads out in a 20 degree cone and is sensitive 20cm to 150cm from the detector.

More pictures below, including some of my messy wiring and glue gun gluing.

Arduino Range to Midi sensor

Arduino Range to Midi sensorArduino Range to Midi sensor

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Laser Harp mk 2

So, if you’ve read my earlier posts, you’ll know I’ve been working on a more musically flexible framed laser harp, mainly achieved by adding functionality not usually present in these devices. At this point, I simply wanted to improve the look and performance of what I had already made.

I decided to invest in some more standard and stable laser diodes, that I purchased from a wholesaler in China. These took more than a little while to be delivered (close to 6 weeks), but when they arrived, I was pleased to find they exactly suited the project. They were generally more consistent with regards to brightness and collimation than the lasers I’d been taking from cheap laser pointers.

Laser harp mk2: plans

Laser harp mk2: plans

Working from the plans above, I built another (MDF) frame to house everything. This took a lot longer than the previous model, as the frame was glued, rather than screwed, and working out a simple, easily repeatable way to create the curves at the corner (with limited tools) was surprisingly the largest challenge I’d encountered so far.

Other than being a little neater (lots more sanding), and including an extra set of buttons to control octave shifts, this version of the harp is essentially the same as the first. The improved quality of the lasers had the bonus of making the velocity sensitivity of each note a little more effective.

laser harp unpowered

Laser harp mk2, unpowered

Laser Harp mk 2, powered

Laser Harp mk 2, powered, long exposure while I played with the beams

So here it is! The only thing left to do is paint for a final finish, and I might even leave that for the next model, as I’m kind of fond of the way this particular model is looking. You’ll notice the above image is a long exposure: I wanted to show a little more clearly where the beams are – they’re not really that visible in a well lit room. I chose to use low power beams as the lasers used in large stage laser harps are fairly dangerous – looking directly into the beams can burn your retinas instantly, or burn your skin if you choose not to wear gloves while using it.

Using lasers with an output <5mw (as I do) are bright enough to give the impression of interacting with light, while being low powered enough that you’d have to stare directly into the beam for several minutes before anything bad happened. This means I (and anyone else) can use it without specialised eye & skin protection.

I will (hopefully) be presenting this version at the MOSI mini maker faire in Manchester in July, so if you live nearby you can see and use it for yourself. Feel free to come along and try it out! I’ll be bringing along a couple of other gizmos I’ve created, of which I’ll write about another time.

P.S. I’m intending to put up a couple of videos of this thing in action, but in reality, an instrument with no haptic feedback whatsoever is a little difficult to play – it might be a while until I get a demonstration I’m happy with!

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A little more information..

I feel I should expand a little on this project:

I’m Chris, an Audio Technology graduate from the University of Salford. A little while ago I decided (as I had some extra free time) I needed some projects to keep me occupied.  I also wanted to make more practical use of the things I had learnt during my degree.

I’d also recently started using the Arduino platform (which is awesome that makes creating electronic devices and distractions incredibly and beautifully easy. So, to introduce myself further to the Arduino, I decided to make a framed laser harp, something a little like this one.

I also decided to refer to other people’s projects as little as possible, to make sure I created it in my own way.

I already possessed the coding skills I’d need from a few earlier projects and my degree, so the main knowledge I lacked was in the process of physically creating the harp itself, rather than the software. So, for the first laser harp at least, I took the laser diodes from a bunch of cheap laser pointers purchased in a corner shop, and built a small test rig consisting of one diode and one photodiode. A couple of tutorials on hooking these things up to an arduino, a bit of coding, and I had a working one note laser harp.

Single note laser harp

This could be hooked up to any standard midi device, and trigger a single midi note. For those reading unfamiliar with midi, it’s something like a musical language for computers, that allows different digital musical devices to communicate. It’s surprisingly versatile, and as such is used more than just expressing a melody. Midi can control a number of different ways of expressing a note (volume, vibrato), or messages used to convey the way an instrument is being played, or even control your stage lighting.

But back to the harp.

I made a simple MDF frame (with a handsaw and some screws) and wired everything up, rewrote the software to allow for more notes, and I had the below:

14 note laser harp

Which (despite the messy wiring) worked brilliantly. Many hours of enjoyment were then had, putting it through various soft-synths and learning about the particular strengths and weaknesses of what I had made.

A few things I wanted to change:

I could only play chromatic scales – it was a simple fix (in the software) to allow the 14 notes to play any kind of scale I wanted. I also added some buttons to allow the user to control the fundamental note of the scale, and what scale was being played (this resulted in a few more hours of procrastination).

Because of the way the software had worked up to then, it only made sense to play midi notes at one volume, that you couldn’t change. A whole heap of musical expression is in it’s dynamics, and I couldn’t let it stay this way. So, I rewrote the code to allow for variable velocity. Up until then, I had assumed as the user’s hand passes through the beam, the light at the receiver end is either “on” or “off”. But in actuality (on the millisecond scale) the process is a gradual covering up of the light, resulting in a nice slope (on a plot of the output). Measuring the gradient of this slope gives you a measure of the velocity of the user’s hand, which I added to the output midi message.

The whole thing was a little bit rough round the edges – I had noticed the lasers fading over time (bad wiring again) and I wasn’t (if I’m completely honest) happy with the quality of the build. I decided it was already time for the next version. To be continued…

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