I'm trying to vary the voltage (6v - 10v) on several leds (about 13 watts). I've used an LM338T with 150 ohm R1 and a 5K linear pot R2. The power supply is 12vdc 5 amp.
Under no load the regulator does exactly as I want (0v - to 10.5v), however when I connect the load the max voltage drops to about 5.5v. No heat generated, chip is cool and resistors are cool.
How did I mess this up?
Under no load the regulator does exactly as I want (0v - to 10.5v), however when I connect the load the max voltage drops to about 5.5v. No heat generated, chip is cool and resistors are cool.
How did I mess this up?