Transistor Circuit Constant Current Source

Hi guys, i need help please. I am a student currently doing a project about LED Light Dimming.

I would like to build a LED Driver/Power Source using Transistor.

Can you guys give me some ideas or suggestion about it?

I am using a LED ARRAY from bridgelux. BXRA-C0400-00000, 440LM, STAR, COOL.

Thank You.

I have posted several LTSpice sims of Led drivers/current source/sinks on these forums.