I have a 12v regulated dc supply to a lm317T regulator. Usual set-up, caps across 12v, across output, 240 ohm resistor output to adjust pin and 5k variable to ground. I put a red led and 470 ohm resistor from +12 to ground to show power on. When I adjust the voltage from the 317, at lowest voltage output the led lights bright. When I raise the voltage to +9,10 etc. the led dims. I've checked the wiring 10 times or more. Maybe I'm just brain fried, but I'm sure the led is across +12v in, which is stable. What am I doing wrong? Is something oscillating? Thanx