Circuit Lake

Electronic Project and Circuit Collection

Voltage Controlled LFO

01/16/2010 Category: Analog, Audio


Low-Frequency Oscillation (LFO) is an audio signal usually below 20 Hz which creates a pulsating rhythm rather than an audible tone. LFO predominantly refers to an audio technique specifically used in the production of electronic music. Ray Wilson designed nice Voltage Controlled LFO (+/-12V to +/-15V) for your modulation needs.

In this project, the frequency can be voltage controlled to add a new dimension to your sound palette. The pulse width of the rectangle wave can be varied between approximately 10% and 90% again lending variability to the modulation capabilities of this LFO. Voltage control can be used to vary the pulse width as well. If you power your circuits with +/-15 volts then observe the recommended changes that are noted on the schematic.

Features :

  • Voltage Control of Frequency (approximate log response, NOT 1V/Octave)
  • Voltage Control of Rectangle Pulse Width
  • Very Low Frequency (1 Cycle per several minutes)
  • Simultaneous Sine, Triangle, Saw, Ramp, and Variable Pulse Width Rectangle Outputs
  • Fine and Coarse Frequency Control
  • Output levels are all approximately +/-5V (+ or – 300 mV)

LFO Project
Project Detail and Documentation