The past month or so I saw an interesting post by Ian Watson so I messaged him to find out what he used.
Simple square wave oscillators using a CMOS 40106 hex inverter and some passive ring mods.
I didn't include ring modulators in this design but I might go back, experiment and incorporate these at some point or in future builds. He also discussed playing around with the capacitors in this circuit and looking at the starve section.
Here it is being run through a pitch shifter.
Power Section
I think I could even get away with 4.7k if I were to build this again as only 50% of the range is no response (although I've not tested it on a proper bright day).
With most of my Lunetta circuits I normally build the same power regulator on the input using a large cap of some type between +/- followed by a 1n400x and after a 104 cap.
I experimented with the large cap found that this not only altered pitch but would rise and fall in pitch as the largest caps filled up, this was nice but I wanted the option for instant power as well so I put 2 different electrolytic caps on a DPDT switch.
To make better use of this I also added a push to break button to have an instant drop in power and make use of this larger caps Attack/Decay behaviour on the circuit.
Six Voice Oscillator
Made using a CMOS 40106 hex inverter with hysteresis. Theres a great section in Nicholas Collins Handmade Electronic Music and in Elliot Williams Logic Noise Articles that cover creating these simple sound circuits.
Outputs
I wanted the ability to split the different outputs as pairs (basically each pair had the same cap value) but also mix them together if I wanted, I had some switched mono jacks so I created a cascaded output. If nothing was plugged into output 1 it routed to output 2 and if no jack was plugged into that it went to 3.
Each pair was mixed with diodes and a 10k load resistor to ground (Nicolas Collins' book helped me understand this).
Housing
Well, I went all out on this, I'd recently purchased a cheap CNC machine to learn how to create wood panels for my modular Lunetta, this project was massive learning curve in using that. I managed to create a panel and a cap for the starve button.
Lessons Learned
I tested the circuit at every stage, and modified it based on how it sounded and felt.
Never try putting a circuit together late at night. I built the circuit and rushed it causing me to start from scratch.
Building a case...
This took the most amount of time and I want the ability to potentially replicate the process. An hour and a half is too long to be running a CNC, I've started to look at creating rubber stamps for labels of basic functions, that way I could easily replicate this process and cut down on the build time.
I also wasn't happy with the way the lettering turned out, after staining the panel I started wondering how to make the labels stand out, I used a thinned down white oil paint but this made a mess and I wasn't happy with it.
Next time - Stain/Paint Panel > Stamp > Varnish > Done.
Developing this further
Around the time I was building this Tom Whitwell of Music Thing posted a device based off a circuit by Ralf Schreiber.
Schreiber's work is based around minimalist robotics, I was particularly interested in his autonomous audio kinetic installation work.
After further research I came across a circuit that he used in some of his installation works http://www.ralfschreiber.com/solarsound.html and I hope to build this with a 5v panel as I have some spare 74HC14 chips.
I also didn't realise that I'd grabbed some of the panel wood I used to make my modular and that the Sundrone Synth was the exact row height of my wine crate cases.
I'm now considering a whole case of solar powered devices alongside some passive elements...
Progress Picture
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