Drummer3 posted:In lieu of the Buck step down module, can you just use a resistor? I would try different values to get the brightness I like.
No. You absolutely need the voltage regulator which is contained in the step down module. It does many jobs at once especially allowing the setting of the voltage to your preference with out any heat build up which could damage your cars. I tried that once with a prewar 3/16 car with no voltage regulator. The metal car got so hot you couldn't touch the roof where the LED strip was attached.
Mark