In 2012, Preben Antonsen, a senior at Yale, approached me about an independent study in analog synthesis. For each semester of study, he completed a major project. The first, completed in Fall 2012, is a single box synth that includes square wave oscillators and a divider. The second, completed in Spring 2013, is a modular synth with LFO, VCO, VCF and a mixer.
The single box:
The modular synth: