After reading project Cree (
https://www.eevblog.com/forum/projects-designs-and-technical-stuff/project-cree-the-led-bench-lighting-project/ ), nice job, I began to think about doing something like it. I have replaced all my outdoor walkway lamps with home made LEDs. Did it simply with LEDs, series resistor and full wave rectifier. So wondered if I could do the same for lighting strip.
My idea: make it from strings of Duris E-5 leds. These are 100+ lumens/watt, about 5mm long, and less than $0.40 for 100 quantities. I have a few of these and have hand soldered to PC board to test. You need to bake above 100C before soldering. Anyway I was thinking of making a strip of these in series on a PC board(s) about 2cm wide. Put about 1 per cm to allow space to solder and spread the heat. They radiate with 120 degree light so should give pretty good uniformity. I would drive about 28 leds in series directly from rectified 120 VAC. Obviously need to shield from touched due to live AC.
I developed a spreadsheet (attached -- Note had to rename from xls to txt for this forum, you can reverse this) to calculate resistor size, currents etc. Because of non-linear nature of LEDs you need to do something like this to make sure you don't exceed the pulsed power limits of the LEDs. Although power is wasted in the resistor, it is the only power wasted other than a small amount by the full wave bridge. I probably would use several small resistors placed along the PC board.
Any comments welcome.