Hello all
I have another question how can I efficiently wire up 18 RGB 3W LED's with common anode? I was going to do series parallel but I dont see how I can with these. I wanted to be able to control each color seperatly.
Thank you
Well you have to do the reverse of what you would do with a common cathode LED. Are you wanting to display any colour on them? Or just R, G or B?
If you want to just light up R,G,B then you want to do the opposite of what you do for a common cathode LED. You would wire up all of the anodes in parallel (if the power supply is big enough). Then you would 'ground' each pin with a transistor circuit.
The LEDs would then be powered by the power supply to the anodes, and the colours would be swithced on and off by 'turning on and off' the ground pin with a transistor. If you want to have any colour then you can PWM the transistors.
Hope this helps,
Mowcius
You can't wire one colour of a common anode RGB LED in seriese as you have found out if you try to draw the schematic. Therefore all LEDs have to be wired in parallel if you want them on at the same time. However as they are high power LEDs you need to use a constant current supply on each individual LED.