Abstract: A low noise, essentially ripple free power supply for supplying power to a telecommunications system includes a gasoline, propane, natural gas or diesel fueled engine driving a rotating field power generator to produce an alternating current output which is then rectified and applied to a special filter circuit to provide an output current having less than 100 mVolts ripple and less than 22 dBrnc noise, which is acceptable to the telecommunications industry. A current sensor connected to the output of said filter circuit monitors the output current to the telecommunications system, and a regulator circuit responds to the voltage and current output of the power supply to control current to the rotating field coils to provide a regulated, substantially constant, output voltage level up to a predetermined maximum current output. A high voltage shutdown circuit shuts down the engine and opens a circuit breaker whenever the voltage output to the telecommunications system exceeds a predetermined level.