screw 172 in its final position an end cap is not shown in order to more clearly illustrate the function of screw 172 in preventing movement of tongue 176 in one preferred embodiment screw 172 can be inserted over caps 18 and 20 fig1 fig1 discloses a block diagram of the electronic components of the fixture 10 and in particular an led controller circuit 124 as illustrated a power supply 68 is connected to the facility current point 136 which can be an electrical outlet or other alternating current source for example 90 vac 277 vac power supply 68 is configured to provide approximately 15 30 volts of direct current to an led controller circuit 124 as shown in fig1 led controller circuit 124 includes a pulse width modulator 152 pwm a capacitance sensor reader 156 in a preferred embodiment capsense successive approximation csa reader a capacitance sensor 160 for controlling light intensity a fet field effect transistor drive circuit 140 and the led panel board 56 in this embodiment the signal from the capacitance sensor 160 controls pwm 152 so that pulses of different width are outputted to control the light intensity pwm 152 signals are amplified by fet 140 to drive the leds 60 accordingly in a preferred embodiment a user can turn on turn off and adjust the brightness of one or more leds 60 or groups of leds in other embodiments in fixture 10 the use of a capacitance sensor situated inside housing 14 allows.