Abstract: An apparatus for controlling pressure instabilities in a combustion chamber. The apparatus includes a detector which detects combustion chamber pressure and outputs a signal indicative of that pressure. A controller then receives the output signal, delays it by a selectable amount of time, and outputs the resultant delayed signal to a pressure chamber device. The pressure chamber device controls the fuel pressure in a fuel line which supplies the combustion chamber. In one embodiment, this pressure chamber device is a cylindrical chamber with closed ends. The pressure chamber has inlet openings and outlet openings which are connected to the fuel line. In some embodiments the bottom of the pressure chamber device includes an elastic diaphragm activated by an electric signal from the controller. In some embodiments the controller involves a delay line for delaying the output signal from the detector.