hi all, I dont post very often but require a little assistance.

I'm working on a lighting project which uses 2x 3mm white leds and 2x white SMD's running off a 12v power supply.

I was wondering if i could use a 470ohm potentiometer on each led/smd to allow for adjustable brightness?

The point being to adjust each led/smd to a desired light level while keeping the circuit board to an absolute minimum due to space limitations.

thanks

 

Do you want them adjustable independently of each other? If not then a 555 PWM circuit will be a solution that won't take up that mcuh space.

You could use a potentiometer and a resistor in series with your LED but you'd have to be careful as pots have generally low current ratings. To overcome this you could use a transistor controlled by a potentiometer.

LEDs don't dim linearly though so you may find you really have to twiddle a lot to get them to dial down, PWM control is much better.

 

If you use a pot, you also need a fixed resistor in series so the current doesn't exceed the LED's rating.

 

independently adjustable.

so power > pot > resistor > led

or

power > resistor > pot> led?

im thinking the second option but might be wrong.

 

independently adjustable.

so power > pot > resistor > led

or

power > resistor > pot> led?

im thinking the second option but might be wrong.

Makes no difference as the same current will flow through the circuit whichever way they are organised.