cycle this quasi regulation is substantially more efficient than a straight resistive load because once the set led current is met the current does not change the power dissipation on the transistor 20 is linear and is a function of the constant current multiplied by the voltage drop across the transistor 20 because of the linear power dissipation in the transistor 20 this also aids in lowering the total power dissipation of the lamp 10 examples of power leds 40 that may be incorporated into led modules 10 of the present invention include the u00bd watt rigel series led available from nichia corporation these leds provide a good thermal junction to case high output and good color binning characteristics in the festoon lamp 10 example shown in the figures each module has three 3 of these leds in series driven at 250 300 ma at 50 duty cycle because of the small size of the festoon lamp 10 and its use of power in the 1 7 2 5 w range the heat sink 14 is used on the back side of the pcb all of the circuit components are smt mounted to the topside of the circuit board 12 and the heat sink 14 is mounted to the rear thermal conductive tape and or epoxies are used to hold the heat sink in place in order to conduct the heat out of the led 39 s and driver transistor thermal plated thru holes under the components connected to pads under the pcb that make contact with the heat sink thru the thermal tape is used to cool the devices the bridge rectifier is has one of the ac input leads thermally connected to one of the bulbs metal end caps to aid in its cooling one of the.