OT DIM OPTOTRONIC OT DIM Light Controller. Osram Optotronic LED controller unit offers an intelligent LED dimming solution for LED lights and luminaires. Due to LED lighting running on low voltages this controller can operate at 1-10 V, whilst delivering fast and precise dimming from 0-100%. Positioned within the circuit between the main power source and the luminaire to manipulate the power. These controllers are suitable for a vast range of LED luminaires with ranging voltages from 10V to 24 V.