as my first project out of the breadboard I've build a basic shield for drivings with a ULN2003A some Leds within a sequence and with fading effects for 3 independent channels. Until now everything fine.. :)
Here you find details on the "shield" http://www.networksoul.net/2010/11/arduino-nativity-set-led-light-controller-hardware/ and the first sketch: http://www.networksoul.net/2010/11/arduino-nativity-set-led-light-controller-%E2%80%93-led-fading-effects/
Now I want to add sunrise and sunset effects with RGB leds. I purchased some 4 pin common cathode 8000 mcd RGB leds.. by mistake.
I have one 3 PWN pins left and the need to control at least 10 leds.. so i need to amplify the current.
I will need to drive the 3 anods (Positive) of each led, can I add a 3 PNP transistor attached to 3 output of ULN2003A (that in an array of NPN transitor)? PWN Pin -> NPN Transistor -> Resistor -> PNP Transitor -> Led -> GND If yes which kind of transistors would you use?