Carlos recorded several compositions in the 1960s as a student at the Columbia-Princeton Electronic Music Center. Two of them were re-recorded and released on "By Request" (1975), "Dialogues for Piano and Two Loudspeakers" (1963) and "Episodes for Piano and Electronic Sound" (1964), both featuring Phillip Ramey on piano. A third, "Variations for Flute and Electronic Sounds" (1964, featuring John Heiss on flute) was recorded and released in 1965 on a Turnabout Records "Electronic Music" compilation. Other known, but unreleased student compositions include "Episodes for Piano and Tape" (1964), "Pomposities for Narrator and Tape" (1965), and "Noah" (1965), a two-hour opera blending electronics with an orchestra. Carlos' first commercial release was "Moog 900 Series – Electronic Music Systems" (1967), an introduction to the technical aspects of the Moog synthesizer released as a nine-minute single-sided mono LP and narrated by Ed Stokes. Part of her compensation for making the recording was in Moog equipment.