Dimming interface for power line

1. A dimming interface circuit, comprising:

a first input power line L 1 with a first switch;

a second input power line L 2 with a second switch;

a neutral input power line N,

a diode bridge:

to which the first input power line is coupled via the first switch;

to which the second input power line is coupled via the second switch; and

to which the neutral power line is directly coupled; and

a phototransistor that is in an OFF state when the first and second switches are closed so that the first and second input lines are connected to the diode bridge, and is in an ON state when only one of the first and second switches are closed.

2. The interface circuit as set forth in claim 1 , coupled to a control circuit that includes a first resistor and a second resistor, coupled to a gate, wherein the gate is open when the phototransistor is in an ON state, causing at least one lamp coupled to the control circuit to be in dimmed state, and wherein the gate is closed when the phototransistor is in an OFF state, causing the at least one lamp to be in a full-intensity state.

3. The interface circuit as set forth in claim 2 , wherein the gate is a MOSFET.

4. The interface circuit as set forth in claim 3 , wherein closing one of the first switch and the second switch causes the phototransistor to enter the ON state.

5. The interface circuit as set forth in claim 3 , wherein closing both of the first switch and the second switch causes the phototransistor to enter the OFF state.

6. The interface circuit as set forth in claim 2 , wherein the second resistor is excluded from the control circuit when the gate is open.

7. The interface circuit as set forth in claim 1 , wherein the second resistor is included the control circuit, in parallel with the first resistor when the gate is closed.

8. The interface circuit as set forth in claim 1 , wherein the phototransistor is included in an opto-isolator.

9. The interface circuit as set forth in claim 8 , wherein the diode bridge includes a first bus that is coupled to first and second diodes, to the first input power line L 1 , and to the opto-isolator via a resistor.

10. The interface circuit as set forth in claim 9 , wherein the diode bridge includes a second bus that is coupled to third and fourth diodes, to the second input power line L 2 , and to the opto-isolator via a capacitor.

11. The interface circuit as set forth in claim 10 , wherein the diode bridge includes a third bus that is coupled to fifth and sixth diodes, and to the neutral power line N.

12. A control circuit for a dimming interface circuit for controlling an electric device, comprising:

a MOSFET that has a source coupled to a first resistor, a first capacitor, and a switch S 2 , and a drain coupled to a second resistor;

wherein the second resistor is excluded from the circuit when the MOSFET is open;

wherein the second resistor is included in the circuit, in parallel with the first resistor, when the MOSFET is closed;

wherein the control circuit is coupled to an interface circuit with a phototransistor, wherein the MOSFET is open when the phototransistor is in an ON state, and wherein the MOSFET is closed when the phototransistor is in an OFF state; and

wherein the phototransistor is included in an opto-isolator that is coupled to a diode bridge and to the control circuit.

13. The control circuit as set forth in claim 12 , wherein the diode bridge comprises:

a first bus that is coupled to first and second diodes, to a first input power line L 1 , and to the opto-isolator via a resistor;

a second bus that is coupled to third and fourth diodes, to a second input power line L 2 , and to the opto-isolator via a capacitor; and

a third bus that is coupled to fifth and sixth diodes, and to a neutral power line N.

14. The control circuit as set forth in claim 13 , wherein the first and second input power lines are coupled to a power source by first and second switches, respectively, and wherein the phototransistor is in the ON state when one of the first and seconds switches is closed and in the OFF state when both of the first and second switches are closed.

15. A method of dimming one or more lamps, comprising:

providing first and second switchable input power lines L 1 and L 2 , and a neutral power line N;

closing one of the switchable input power lines L 1 or L 2 to cause a phototransistor in an interface circuit to turn ON, which causes a MOSFET in a control circuit to be in an open state during which at least one lamp coupled to the control circuit is in a dimmed state; and

closing both of the switchable input power lines L 1 and L 2 to cause a phototransistor to turn OFF, which causes the MOSFET to be in a closed state during which the at least one lamp is in a full-intensity state.

16. The method according to claim 15 , wherein closing the MOSFET causes a second resistor to be included in the control circuit in a parallel configuration with a first resistor, thereby reducing resistance in the control circuit and permitting the at least one lamp to operate at full intensity.

17. The method according to claim 16 , further including coupling one or more non-dimming ballast circuits input power lines L 1 and L 2 , and to the input neutral power line N.