I am very new to building any type of circuit beyond putting batteries in a flashlight. Before bugging y'all with my question, I searched this as well as other forums and did not find an answer. I want to build a few big aquarium lights similar to the grow lights one sees on ebay. The first thing I did was buy some LED's off ebay, clean some old PCB's from computers (hard to find the long skinny ones new so I cut my own) and place two rows of 30 LED's all connected to 2 leads (all the positive on one lead the negative on the other) Then I connected it to an of the shelf 3.5v transformer from a cordless phone. It worked fine. Then I started looking on forums for how to do a much bigger light and read how one cant do what I did without resistors and this or that other component and now I'm all confused. I want to build three lights each using 100 white 5mm 3.5v LED's and 50 of the same in blue and 50 in red 1.5v LED's. The three colors will have their own on/off switch. Real simple, nothing proprietary. Just dont see why I should spend over $500 each for something I can make for less than $50 each. I already have the housings. Can someone explain the HOW (using simple idiot terms) or even give me a basic diagram?