A coffee machine for producing and dispensing coffee-based beverages comprising: at least one hydraulic pump, a boiler and a brewer unit equipped to receive ground coffee and pass through hot water received from the boiler, and comprising a flow meter to measure the flow of water and a control unit receiving electrical signals from the flow meter and controlling the at least one hydraulic pump to regulate the flow rate of water, wherein the coffee machine incorporates an input of the control unit that establishes a variable set-point value of the flow rate that depends on a desired fixed extraction time of the ground coffee received in the brewer unit, wherein the control unit is arranged to calculate a difference between the variable setpoint value of the flow rate, and a measured value from the flow meter, and that the control unit supplies this difference as an error value to a control tool, and wherein the control tool drives a converter that converts DC power at a powerline into an amplitude variable electrical pulse signal at a driver line that drives the at least one hydraulic pump.