Mfa 919d2 series pwm voltage speed regulator modules mfa 919d2 the mfa 919d2 voltage speed regulator has a variable output providing smooth progressive speed control from min to max ideal for use in controlling motors and geared motors it can also provide a dimmer facility for low voltage lighting circuits 6 to 15v onlyit employs pulse width modulation pwm circuitry giving a constant voltage output speed control is achieved by varying the width of the output pulse maximum rated