Wireless lighting devices and applications

1. A lighting unit comprising:

a power input adapted to receive power via a power supply circuit, wherein the power supply circuit receives a supply of AC power through a switch and includes a source of DC power;

at least one light emitting diode (LED) adapted to receive power via the power input;

a sensor configured to generate an output indicative of an impedance associated with the power supply circuit; and a controller configured to:

determine an operational state of the switch through a plurality of measurements of the sensor output; and cause DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and the operational state of the switch indicates that the switch is in a closed or partially closed state, wherein the controller is further configured to:

determine a first impedance value associated with the power supply circuit corresponding to an open operational state of the switch;

determine a second impedance value associated with the power supply circuit corresponding to a closed operational state of the switch;

establish a threshold impedance level based on the first and second impedance values; determine a third impedance value associated with the power supply circuit, when AC power is not present on the power input; and

cause the DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and a comparison between the third impedance value and the threshold impedance level indicates that the switch is in a closed state.

2. The lighting unit of claim 1 , wherein the controller is further configured to:

determine a manually set threshold impedance level;

determine an impedance value associated with the power supply circuit, at least when AC power is not present on the power input; and

cause the DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and a comparison between the impedance value and the manually set threshold impedance level indicates that the switch is in a closed state.

3. The lighting unit of claim 1 , wherein the sensor generates the output indicative of an impedance associated with the power supply circuit as part of a time domain reflectometry process.

4. The lighting unit of claim 1 , wherein the source of DC power is integrated into the lighting unit.

5. The lighting unit of claim 1 , wherein the source of DC power includes at least one of a rechargeable battery, fuel cell, or super capacitor.

6. The lighting unit of claim 5 , wherein the controller is further configured to control charging of the at least one of a rechargeable battery, fuel cell, or super capacitor.

7. The lighting unit of claim 1 , wherein the source of DC power includes an alkaline battery.

8. The lighting unit of claim 1 , further comprising at least one photovoltaic cell.

9. The lighting unit of claim 8 , wherein the photovoltaic cell is configured to recharge the source of DC power.

10. The lighting unit of claim 8 , wherein the photovoltaic cell is configured to provide power directly to the at least one LED.

11. The lighting unit of claim 1 , wherein the lighting unit is configured for mounting to an Edison socket.

12. The lighting unit of claim 1 , further including a timer, wherein the controller is further configured to control a supply of power to the at least one LED based at least in part on an output of the timer.

13. The lighting unit of claim 1 , further including a light sensor configured to sense a level of ambient light, wherein the controller is further configured to control a supply of power to the at least one LED based at least in part on an output of the light sensor.

14. The lighting unit of claim 1 , further including a motion sensor, wherein the controller is further configured to control a supply of power to the at least one LED based at least in part on an output of the motion sensor.

15. The lighting unit of claim 1 , wherein the controller is further configured to turn the at least one LED on or off, change an illumination level of the at least one LED, flash the at least one LED, or change a color content of illumination of the at least one LED.

16. The lighting unit of claim 1 , wherein the switch includes a dimmer switch.

17. A lighting unit comprising:

a power input adapted to receive power via a power supply circuit, wherein the power supply circuit receives a supply of AC power through a switch and includes a source of DC power;

at least one light emitting diode (LED) adapted to receive power via the power input; a sensor configured to generate an output indicative of a resistance, or capacitance associated with the power supply circuit; and a controller configured to:

determine a plurality of resistance or capacitance values associated with the power supply circuit based on the output of the sensor; determine an operational state of the switch based on the determined plurality of resistance or capacitance values; and

cause DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and the operational state of the switch indicates that the switch is in a closed state, wherein the controller is further configured to: determine a first resistance or capacitance value associated with the power supply circuit corresponding to an open operational state of the switch;

determine a second resistance or capacitance value associated with the power supply circuit corresponding to a closed operational state of the switch;

establish a threshold resistance or capacitance level based on the first and second resistance or capacitance values;

determine a third resistance or capacitance value associated with the power supply circuit, when AC power is not present on the power input; and

cause the DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and a comparison between the third resistance or capacitance value and the threshold resistance or capacitance level indicates that the switch is in a closed state.

18. The lighting unit of claim 17 , wherein the controller is further configured to:

determine a manually set threshold resistance or capacitance level;

determine a resistance or capacitance value associated with the power supply circuit, at least when AC power is not present on the power input; and

cause the DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and a comparison between the resistance or capacitance value and the manually set threshold resistance or capacitance level indicates that the switch is in a closed state.

19. The lighting unit of claim 17 , wherein the source of DC power is integrated into the lighting unit and includes at least one of a battery, fuel cell, or super capacitor.

20. The lighting unit of claim 17 , further comprising at least one photovoltaic cell, wherein the photovoltaic cell is configured to at least one of recharge the source of DC power or provide power directly to the at least one LED.

21. A retrofit lighting fixture comprising:

a housing configured for installation into a preexisting structure;

a power input adapted to receive power via a power supply circuit associated with the preexisting structure, wherein the power supply circuit receives a supply of AC power through a switch;

at least one light emitting diode (LED) adapted to receive power via the power input;

a source of DC power adapted to selectively provide DC power to the at least one LED;

a sensor configured to generate an output indicative of an impedance, resistance, or capacitance associated with the power supply circuit; and

a controller configured to:

determine an operational state of the switch through a plurality of measurements of the sensor output; and

cause DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and the operational state of the switch indicates that the switch is in a closed state, wherein the controller is further configured to: determine a first impedance, resistance, or capacitance value associated with the power supply circuit corresponding to an open operational state of the switch;

determine a second impedance, resistance, or capacitance value associated with the power supply circuit corresponding to a closed operational state of the switch;

establish a threshold impedance, resistance, or capacitance level based on the first and second impedance values;

determine a third impedance, resistance, or capacitance value associated with the power supply circuit, when AC power is not present on the power input; and

cause the DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and a comparison between the third impedance, resistance, or capacitance value and the threshold impedance, resistance, or capacitance level indicates that the switch is in a closed state.

22. The lighting unit of claim 21 , wherein the controller is further configured to:

determine a manually set threshold impedance, resistance, or capacitance level;

determine a impedance, resistance, or capacitance value associated with the power supply circuit, at least when AC power is not present on the power input; and

cause the DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and a comparison between the impedance, resistance, or capacitance value and the manually set threshold impedance, resistance, or capacitance level indicates that the switch is in a closed state.

23. The lighting unit of claim 21 , wherein the source of DC power is integrated into the lighting unit and includes at least one of a battery, fuel cell, or super capacitor.

24. The lighting unit of claim 21 , further comprising at least one photovoltaic cell, wherein the photovoltaic cell is configured to at least one of recharge the source of DC power or provide power directly to the at least one LED.

25. The lighting unit of claim 1 , wherein the lighting unit comprises a bulb, tube, lamp, lighting fixture, or retrofit fixture.

26. The lighting unit of claim 1 , wherein the controller is further configured to change at least an illumination level of the at least one LED to increase the energy efficiency of the lighting unit.

27. The lighting unit of claim 26 , wherein increasing the energy efficiency of the lighting unit includes decreasing DC power supplied to the at least one LED from the source of DC power.

28. A lighting unit comprising:

a power input adapted to receive power via a power supply circuit, wherein the power supply circuit receives a supply of AC power through a switch and includes a source of DC power;

at least one light emitting diode (LED) adapted to receive power via the power input;

a sensor configured to generate an output indicative of an impedance associated with the power supply circuit; and a controller configured to:

determine whether AC power is present on the power input;

determine an operational state of the switch, when AC power is not present on the power input, through a plurality of measurements of the sensor output; and

cause DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and the operational state of the switch indicates that the switch is in a closed or partially closed state, wherein the controller is further configured to:

determine a first impedance value associated with the power supply circuit corresponding to an open operational state of the switch;

determine a second impedance value associated with the power supply circuit corresponding to a closed operational state of the switch;

establish a threshold impedance level based on the first and second impedance values;

determine a third impedance value associated with the power supply circuit, when AC power is not present on the power input; and

cause the DC power to be supplied to the at least one LED from the source of DC power when AC power is not present on the power input and a comparison between the third impedance value and the threshold impedance level indicates that the switch is in a closed state.

29. The lighting unit of claim 28 , wherein

the sensor generates a plurality of signals and

the monitoring includes monitoring responses to at least two of the plurality of signals to perform an impedance discontinuity check.

30. The lighting unit of claim 28 , wherein

the sensor generates a plurality of pulses and

the monitoring comprises monitoring reflective signals from at least two of the plurality of pulses.