Hi, so I'm new to this forum and I'm sorry if I'm not posting in the right place. I am kind of new to building circuits. I am trying to build a current limiter for a one watt led. I have been searching tutorials and designs for some time and everyone i find is about 5mm leds. My main issue is i have a assortment of transistors and every design i find say you must have this one transistor but a different one on each design. My first question is, how do you choose which transistor to use? I under stand how the design works in a way but not sure what parts to use in my situation. I have not decided exactly what I'm doing yet but its either going to be one or two 1watt 3-3.4 volts 300-350ma led. Any insight on how to build this and what resister and transistors to use would be great. I am planning on using either a usb power supply if possible or a 12v supply.