The NovaDrone is an open source, analog sound and light synthesizer.
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It utilizes 6 op amp based oscillators.  These signals combine through 3 simple comparators to create 3 PWM (pulse width modulation) signals which are used to create sound at the same time as controlling the brightness of three colored LEDs. PWM is a good way tocontrol the brightness of LEDs. It also results in an interesting phasing effect when applied to audio square waves. 

3 of the oscillators are equipped with SYNC inputs that allow syncing with the other oscillators via routing switches as well as a connection strip at the bottom of the board. The sync feature causes the synced oscillator to generate harmonics of the master oscillator and is very effective for making harmonious drones. 
Each oscillator can also be synced to the PWM output of any other channel. This creates a very interesting harmonic modulation effect resulting from the master pitch and PWM rate.  
The connection strip offers all oscillator outputs (square and triangle), pwm out and 3 sync inputs. This allows the NovaDrone to easily interface with other NovaDrones or a wide range of other circuits. The picture above shows a bread board attached to the connection strip. This allows for on the fly circuit development. I'm considering making the breadboard connection a standard feature of a <em>deluxe</em> model NovaDrone. 
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PCB:
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SCHEMATIC:
V1.2 fixed virtual ground error
5/1/2012
V1.3 fixed signal path errors
5/16/2012 
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PROTOTYPING:
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