Another LED Thread...

Now I know after browsing around here you guys are bombarded with LED questions everyday but I just have to ask and confirm a few things I have in mind...

I am modding my own LED light for an automotive application, and this is the first LED project I am doing. I have a couple of ideas for how I want to do it, but I need some assistance from the electronics people on TBCS. This whole application will have to fit within a 32MM x 35MM PCB board.

I want this light to be fadable, if possible. For example, when current is removed, the LED's will fade out. Maybe switch to a different circuit and fade a different set of LED's out. Is this possible, and how? Note: there will NOT be a constant power source to this circuit.

The power source of the car is steady, but not extremely so. I've tested other LED's on the circuit but there is a noticable change in brightness between when the car is on and when the car is off. Is there a way I can steady the output power to provide consistent brightness? I'm thinking capacitors...

There will be at least 20 LED's in this circuit. I was going to arrange them into 5 rows of 4 LED's in series. There will be 1 main power contact and 1 main ground contact. How many resistors do I need? I know I need at least 1 for each series of LED's, but is it possible to consolodate and use only 1 resistor for the entire circuit? Also, will that change what kind of resistor I need?

Thanks.

-Cool-

Nobody has any help or advice or anything?

-Cool-

hmm. I would stick with on resistor for each LED personally. Yeah capacitors would work maybe. Rig it up and try. They would probably dim pretty quick though.

Some one correct me If i'm wrong.