Doepfer A-111-1

Module A-111-1 (VCO 2) is a voltage controlled oscillator. The VCO has a range of about 12 octaves, and produces four waveforms simultaneously: pulse (rectangle), sawtooth, triangle and sine waves. The VCO's frequency is determined by the position of the range switch, tune and fine tune controls, and the voltage at the two pitch CV inputs, CV 1 and CV 2.

Footage (the octave of the fundamental) is set by the Range control, which has seven octave steps. The Tune control is used for coarse tuning, and the Fine control for fine tuning of the VCO pitch. The A-111 can be modulated by both exponential and linear FM (frequency modulation). You can control the pulse width of the square wave either by hand, or by voltage control - Pulse Width Modulation, or PWM for short.
The A-111 has inputs for Hard Sync and Soft Sync.