 While ring modulator circuit information was readily available, it was a 1961 article by Harald Bode in "Electronics Magazine" that gave Oberheim the information he needed to design and hand-build one for musical application.Oberheim also built a ring modulator for Don Ellis.After hearing about Oberheim's device, film composer Leonard Rosenman contacted him for a ring modulator to use in the production of the Beneath the Planet of the Apes film soundtrack.