a dimming control system includes a first circuit and a second circuit . first circuit is coupled in series with the ac line source and receives brighten and dim commands from a user . the brighten and dim commands are communicated to second circuit by momentarily altering the ac voltage waveforms observed by second circuit . second circuit provides an adjustable dimming control voltage that is coupled to existing dimming control circuitry within an electronic dimming ballast . the dimming control voltage is adjusted by the second circuit in dependence on the observed ac voltage waveforms .