For our summer project at university, we had the opportunity to design an analog synthesizer in the circuit simulator LTSpice. My group, consisting of me, George and Prateek, implemented a modular design with low frequency oscillator, voltage controlled amplifier and filter, both controlled by an ADSR module, to create some awesome sounds. Since this project is no longer assigned for subsequent years, I can share the schematic that we created.

We tested our design and measured its performance characteristics. We created our report in LaTex which has a cool CircuitTikz library for creating circuit diagrams. The lt2circuitikz program which is a program that converts LTspice files to Circuitikz was incredibly useful for creating these diagrams in LaTex.

Here is some music generated using our synth. I used an Excel spread sheet to key in the notes and note lengths after which I created a formula to convert them to frequencies and then to voltages. Using a small Python program, I converted these voltages to a piecewise voltage directive in LTSpice. The simulation took a very long time to complete (approx 6hrs) but it was definitely worth it.

Can you guess the song?