A ring choke power converter comprising - an input for receiving an input power with a nominal mains level, wherein said nominal mains level is variable and falls within at least 90V to 240V; - a main power switch driven by the input power, wherein the main power switch is a main power bipolar transistor; and - a control circuit (Q2, Q3) for controlling a control current of the main power switch; wherein the control circuit (Q2, Q3) is adapted to sense the level of the input power and draw current from a control terminal of the power switch according to the level, and said control circuit is adapted to operate in linear region and increase the drawn current along with the increase of the level throughout said variable nominal mains level of the input power, wherein the control circuit comprises: - a Darlington bridge with a first transistor and a second transistor, the first transistor with a base terminal connected to a circuit position indicative of the voltage amplitude of the input power, the second transistor with a base terminal connected to an emitter terminal of the first transistor and a collector terminal connected to the control terminal of the main power switch and a collector terminal of the first transistor; and - a resistor network comprising at least one resistor (R3, R7) coupled to the emitter of the second transistor for regulating the amplification of the second transistor and keep the second transistor working at linear region throughout the variable nominal mains level of the input power. - an input for receiving an input power with a nominal mains level, wherein said nominal mains level is variable and falls within at least 90V to 240V; - a main power switch driven by the input power, wherein the main power switch is a main power bipolar transistor; and - a control circuit (Q2, Q3) for controlling a control current of the main power switch; wherein the control circuit (Q2, Q3) is adapted to sense the level of the input power and draw current from a control terminal of the power switch according to the level, and said control circuit is adapted to operate in linear region and increase the drawn current along with the increase of the level throughout said variable nominal mains level of the input power, wherein the control circuit comprises: - a Darlington bridge with a first transistor and a second transistor, the first transistor with a base terminal connected to a circuit position indicative of the voltage amplitude of the input power, the second transistor with a base terminal connected to an emitter terminal of the first transistor and a collector terminal connected to the control terminal of the main power switch and a collector terminal of the first transistor; and - a resistor network comprising at least one resistor (R3, R7) coupled to the emitter of the second transistor for regulating the amplification of the second transistor and keep the second transistor working at linear region throughout the variable nominal mains level of the input power. - a Darlington bridge with a first transistor and a second transistor, the first transistor with a base terminal connected to a circuit position indicative of the voltage amplitude of the input power, the second transistor with a base terminal connected to an emitter terminal of the first transistor and a collector terminal connected to the control terminal of the main power switch and a collector terminal of the first transistor; and - a resistor network comprising at least one resistor (R3, R7) coupled to the emitter of the second transistor for regulating the amplification of the second transistor and keep the second transistor working at linear region throughout the variable nominal mains level of the input power.