Tag Archive: AVR

2nd TANR Prototype, workshop ready.

2nd TANR Prototype, workshop ready.

TANR is a tiny AVR based synthesizer. It is not too far from Ljudmaskin, but there are few differences. Most important is that it has more touch contacts. It has three main contacts that are chained with resistors two form additional contacts. I have also added a potentiometer that is used to change modes between different synthesis algorithms.

There are two main influences for my synth. First one is Lumenoise, an audiovisual synthesizer by Niklas Roy. Those of you who have had a chance of trying this thing, know that its synthesis algorithm is a weird mix of control and total lack of control, both at the same time. I wanted to have something that would have the same feel than Lumenoise. This is where the synthesis algorithm kicks in. I have done workshop about algorithmic music players. That workshop was based on concept of ‘one line symphonies’ by Finnish demoscene veteran Viznut.

The circuit diagram of TANR. The circuit consists of Attiny85 and lm386.

The circuit diagram of TANR. The circuit consists of Attiny85 and lm386.

The schematics of TANR show that most of the magic happens in software. How TANR works is that it is using bunch of one line symphonies, switching between them and modulating their parameters based on readings from touch contacts, number of clock cycles etc. I think there is a tiny pinch of astrology in the algorithms as well. With high refresh rates one gets nicely colored and in a way harmonic noises and on some settings effects or even melodies. I’m still in the process of polishing and rewriting the software bit so wont include it here (yet). End result is this:

Soothing sounds of TANR.

As in my previous workshops, no PCBs were used. Instead spot board and insulated metal wire was used. New innovation on this workshop was to use a photo with final layout between components and the board to help with placement of the components. I have to say that project like this starts to be at the limits of spotboard technique and might be that after working months with DIMI, I’m fluent Eagle user, could have proper PCBs made in the future iterations. Although I think it is useful to master creating circuit boards from scratch with spot board.

Workshop results!

Workshop participants and couple finished synths!

As always I’m up to giving this workshop few times in the future. This workshop is suitable with people with previous experience on soldering and it takes around 5 hours to finish. Drop me a line if you would be interested in organizing one!

EXCTR-network close up.

EXCTR-network close up.

The Spatial Aural Exciter is a project initiated by Samy Kramer. It is essentially a cheap multichannel system consisting of small synthesizer boards that can be connected together in different configurations. Systems can comprise of hundreds of boards. Especially in large systems allow generating big masses of sound that can be moved in space. Individual boards are based on ATMega328 microcontroller and are compatible with Arduino libraries.

Example of exctr-network configuration.

Example of exctr-network configuration.

Exctr-system consists of several different parts. One part is a software running on computer that is sending parameters for individual synthesizer nodes. The communication between computer and individual nodes is done by using MIDI like protocol. The synthesizer nodes are connected in series. Commands are sent from the computer to the string of nodes. Nodes will forward the data to the next node until correct receiver has been reached. Largest practical length for one string is around 40 nodes. In larger networks, multiplexer nodes can be used to combine parallel strings to one network.

Individual synthesizer nodes are small electronic boards consisting mainly on ATmega328 microcontroller and a piezo speaker. The software turns microcontroller to a simple monophonic synthesizer. As one would expect, one can alter the waveform, frequency and amplitude in real time. Band limited sound synthesis algorithms are currently under development.

Exctr-system has been exhibited in several exhibitions over the Europe. Currently this project is actively developed and so far biggest configuration will be exhibited in Turku July 2014.

The software for the single board can be found at http://launchpad.net/thespatialauralexciter. The official website of the project can be found at http://exctr.net/.

synakynä schematics

I gave a workshop as part of Super Public Art School (for a second time) in Titanik Gallery 6 June 2013. The topic was a hand shake between visual and sound arts: a synthesizer pencil. I named it Synakynä (a pencil synth in Finnish). Below you can witness some fooling around with first working (after many failed) prototype.

Synakynä is augmented version of drawdio but it uses ATtiny85 microcontroller instead of a 555 timer. This greatly expands the sonic range of the instrument. At the workshop, preprogrammed ATtinys are provided, but if you wish to modify the code and upload it by yourself, source code for Synakynä is available and written using Arduino IDE. One also needs to install ATtiny definitions. To upload the code you can use either ISP programmer or Arduino board as described in previous link.

To play Synakynä, you need to draw continuous and as thick line as possible on paper while touching one end of the line with your other hand. This will cause a small current to flow through the circuits of the pencil, your drawing and your body (study the diagram above for the details). The microcontroller is measuring amount of current and using this information to alter pitch of the synthesizer and tempo of blips. It is also possible to replace pencil with more or less anything (fruits, food, skin) that has similar resistance. Feel free to experiment.

The current code has multiple different modes written into it. Every time Synakyna is switched on, different mode will be chosen.

Parts list:

  • Pencil (HB,2B, as soft as possible)
  • Piezo
  • ATtiny85 (+ optional 8-dip socket)
  • 300k resistor
  • 680pF capacitor
  • Power switch
  • Battery holder (2032)
  • Battery (2032, 3V)
  • Piece of spot board (22×9 holes)
  • Metal wire, uninsulated
  • Wire
  • Piece of aluminum foil or copper tape

Tools needed:

  • Soldering iron and solder
  • Wire strippers
  • Knife or saw
  • Pencil sharpener

The circuit board is constructed on spot board by using thin metal wire to form the actual circuit. It is a neat little technique that is for some reason surprisingly rare. Compared to etched or strip boards this technique allows improvising the actual layout of the board on the fly without spending huge effort on layout design. Those not keen on improvising can find a fairly compact layout below.


Synakynä layout suggestion.

Stuff drawn with pen are on the copper side of the board while parts drawn with pencil are on top side of the circuit board. Pay attention for the trace going to the left leg of the piezo. It should go past the trace coming from the power switch at the top side of the board. Diagram is from the top side (the side the components are) of the board.

pkas paks

Above you’ll see results of the workshop. Ten synths were built and all of them successfully. Well done!