Apparatus is provided for controlling both the high voltage and turbine speed in a rotary atomizer used in the electrostatic spray coating of a workpiece such as an automotive vehicle. A rotary bell cup spray atomizer carried by a maneuverable robot arm is charged to a high voltage potential which charges the atomized particles exiting the bell cup. The bell cup is rotatably driven by a turbine. The voltage to and speed of the atomizer, respectively, are regulated by a high voltage multiplier and a fiber optic transceiver. A low voltage electrical source remote from the robot arm assembly powers the voltage multiplier and the transceiver, both housed adjacent the atomizer, via two shielded, low-voltage, electrical cables extending from the low voltage source to the housing. One of the electrical cables connects to the multiplier to regulate the voltage applied to the atomizer. The other connects to the transceiver such that incoming electrical signals to the transceiver are converted to light signals which are transmitted to the turbine through at least one optical fiber, which light signals are then reflected backwardly from the turbine through at least one second optical fiber back to the transceiver and converted to electrical signals thereat. These signals control both the voltage applied to the particles and the rotational speed of the turbine.