GE LED10DASW9 LED bulb
The GE LED10DASW9 LED bulb is rated at 10.5w and 800 lumens light output equivalent to a 60W incandescent bulb. There are 16 upward facing LEDs mounted on a PCB which is riveted to an aluminum heat sink disk. A white plastic cylinder is clipped to the heat sink/PCB assembly inside the ring of LEDs to reflect light to the side for more uniform illumination. The heat sink/PCB assembly is pressed into an additional aluminum heat sink within the A19 base.
A single sided printed circuit board inside the A19 base provides AC to DC conversion. On one side of the board larger through-hole components such as transformer, inductor and capacitors are located. On the other printed side the surface mounted components are located. The semiconductor content of this product consists entirely of discrete components including diodes, a diode bridge, and bipolar transistors. There are no integrated circuits. The AC to DC conversion circuit connects to the LED assembly through a 2-pin connector.
The circuit is a non-isolated buck-boost converter that generates a DC voltage for driving the LEDs from the full wave rectified 120 volt AC input. The rectified AC is not directly filtered to an intermediate DC voltage because this would require a large capacitor. Instead, the full wave rectified AC voltage varying from 0 to approximately 170 volts peak is fed through a passive LC filter to block high frequencies and provided directly to the switching regulator consisting of an NPN switch transistor, transformer, diode, and large electrolytic output capacitor. The switching regulator switches at a much higher frequency than the 60Hz input, and adjusts the switch duty cycle based on the input voltage to maintain output current through most of the 60Hz period. The transformer secondary is not used for isolation, but controls the base emitter-voltage of the main switch transistor via a transistor clamp circuit. Transient protection is provided by a 270v varistor and 5 ohm fuse resistor at the AC input.
A polar coordinate graph shows the light intensity of the GE LED10DASW9 at 4 different power levels adjusted with a triac dimmer. 0 degrees is the top of the bulb and 180 degrees is the base of the bulb where the light is completely blocked. Full power intensity shows a maximum of 4200 lux and drops off rapidly at +/-90 degrees. Integrating intensity over the entire surface gives a total light output of 640 lumens, short of the rated 800 lumens. However a 60W incandescent light bulb provided only 400 lumens under the same measurement conditions so there is probably a significant calibration error. Power consumption was measured at 11 watts, slightly exceeding the rated power consumption. Energy efficiency of the bulb can be calculated by converting lumens to watts on the basis of the photopic luminosity function (683 lumens/watt) which approximates the range of wavelengths visible to the human eye at normal intensities. The GE LED10DASW9 efficiency in converting electrical power to optical power at visible wavelengths is calculated at 8.5% under full power. For comparison the 60W incandescent bulb is calculated at only 1.0% efficiency.