I have a circuit which switches 12V to power a 12V, 20mA LED (Marl 512-997-21, RS: 310-6921). I need to modify this to add some simple dimming control. The current circuit doesn't have any resistors in-line, it just switches 12V directly so I assume this LED has a resistor built in.
I have a analogue control voltage available (0-10V), so could I simply feed this into a op amp with 15V supply (large enough to output 12V and suitable power drive capability to source 0.5W) to vary the output voltage? Looking online it seems constant current and PWM control is recommended but this seems a bit overkill for what I'm trying to do requiring additional complexity. I really need this to be as simple as possible with minimal component changes to the existing design whilst still being "good". Linear brightness control would be desirable. Any advise is greatly appreciated. I thought this would be simple looking online but there seems to be some very complex methods of doing this.