Hello...
I have an RGB LED Strip and i want to drive it with an PWM.
I have a problem to interface the LEDs.
The stripes have constant current sources and have an common 12V supply and a GND connection for each color. At 12V supply each line sinks around 100mA.
So please, how I connect the LEDs to the PWM Ports of the board and which parts (I think about MOSFETs or Bipolar Transistors) I need to connect it.
Best Regards Huber Florian
In stead of transistors you can use a ULN2003 (7 Darlington transistor array). It is cheaper and takes up less space and it can handle up to 500mA pr. channel.
See this for hookup info :
I would put an additional 100 Ohm resistor in between each of the arduino pins and the ULN2003 to protect the pins.
thank you very much!
Now it should be no problem to do this project.
going shopping 
it can handle up to 500mA pr. channel.
Look up the spec because I think it can't take that much on each channel at the same time.
thank you! I have just downloaded the datasheet
http://www.datasheetcatalog.net/de/datasheets_pdf/U/L/N/2/ULN2003.shtml
it says up to 500mA per driver and i need only 100mA per channel so I have 300mA max.
Best regards itshorty