[sdiy] network additive synth

[Daniel Kruszyna]

I've made some progress on my networked additive synth. I haven't
written much yet about it but I put some pictures up on my website.

http://krue.net/add/add-front.jpg

shows the entire synth so far. It consists of four identical oscillator
modules connected to one of my cansynth boards via a CAN bus. The
cansynth module handles the MIDI stream and sends events to the
oscillators. The small bit of perfboard contains the optoisolator
and associated parts for the MIDI ports. The breadboard contains a mixer
to combine the individual oscillator signals, some LEDs for debugging,
and some other parts in storage on the left that you can ignore.

There is also a simple UI available on the db9 serial port to send
configuration data to the oscillators and monitor the i/o ports.

Here is another photo of just the core circuit boards:

http://krue.net/add/add-core.jpg

And finally, here is just one of the oscillators:

http://krue.net/ollie/ollie-front.jpg

I call this design "ollie". It consists of an attiny26 with mcp2515
CAN controller. The output is created by an 8bit r2r ladder followed
by a dca controlled with a digital potentiometer. I have a schematic
I will post once I fill in the part values.

Each oscillator controls one partial of one note. They have identical
code and receive the patch data over CAN. I have the code to create
the harmonics functional and am now working on the envelopes.

Just wanted to let you know what I've been up to...

-- Daniel