A device is described which generates sinusoidal waves of radiant power for use in visual experiments. The instrument covers a continuous range of frequencies from 2 to 75 cps, modulation amplitudes from 0.001 to 1.0, and luminance levels from 0.01 to 1500 mL. Frequency, amplitude, and luminance controls are mutually independent. Both ``equal‐energy'' white light and narrow‐band chromatic stimuli are provided.