A door actuator, having • an electric motor, which is driven in a generative manner in a first operating direction, and a brake circuit configured to influence a movement of a connected door in at least one movement direction, with the at least one electric motor, wherein the brake circuit is configured, in the case of a generative operation of the electric motor of the door actuator, to supply its generatively produced energy to a bipolar transistor as a load resistance in a first operating direction of the electric motor opposed to a movement direction, and wherein the brake circuit has a voltage regulator, which - regulates a voltage applied to the base terminal of the bipolar transistor according to a generator voltage produced in the electric motor to an associated control voltage based on a reference voltage and comprises - a reference input for applying the reference voltage, - a voltage input and - an output for outputting the control voltage, wherein, in the case of generative operation of the electric motor, • a first voltage terminal of the electric motor is coupled to the collector terminal of the bipolar transistor and to the voltage input of the voltage regulator and is coupled via a first resistor branch, comprising at least one electric resistor, to the reference input of the voltage regulator and • a second voltage terminal of the electric motor is coupled to the emitter terminal of the bipolar transistor. • an electric motor, which is driven in a generative manner in a first operating direction, and a brake circuit configured to influence a movement of a connected door in at least one movement direction, with the at least one electric motor, wherein the brake circuit is configured, in the case of a generative operation of the electric motor of the door actuator, to supply its generatively produced energy to a bipolar transistor as a load resistance in a first operating direction of the electric motor opposed to a movement direction, and wherein the brake circuit has a voltage regulator, which - regulates a voltage applied to the base terminal of the bipolar transistor according to a generator voltage produced in the electric motor to an associated control voltage based on a reference voltage and comprises - a reference input for applying the reference voltage, - a voltage input and - an output for outputting the control voltage, wherein, in the case of generative operation of the electric motor, • a first voltage terminal of the electric motor is coupled to the collector terminal of the bipolar transistor and to the voltage input of the voltage regulator and is coupled via a first resistor branch, comprising at least one electric resistor, to the reference input of the voltage regulator and • a second voltage terminal of the electric motor is coupled to the emitter terminal of the bipolar transistor. - regulates a voltage applied to the base terminal of the bipolar transistor according to a generator voltage produced in the electric motor to an associated control voltage based on a reference voltage and comprises - a reference input for applying the reference voltage, - a voltage input and - an output for outputting the control voltage, wherein, in the case of generative operation of the electric motor, • a first voltage terminal of the electric motor is coupled to the collector terminal of the bipolar transistor and to the voltage input of the voltage regulator and is coupled via a first resistor branch, comprising at least one electric resistor, to the reference input of the voltage regulator and • a second voltage terminal of the electric motor is coupled to the emitter terminal of the bipolar transistor. • a first voltage terminal of the electric motor is coupled to the collector terminal of the bipolar transistor and to the voltage input of the voltage regulator and is coupled via a first resistor branch, comprising at least one electric resistor, to the reference input of the voltage regulator and • a second voltage terminal of the electric motor is coupled to the emitter terminal of the bipolar transistor.