I'm building a series of gadgets for my kids that mostly (microchip, sensors) run off 3.3 but there are some switches and possible servos that run off 12v.
My original idea was just to have two wires, one for 12v and one for 3.3v but I don't like that since most of the items won't need the 12v and it adds clutter in the wiring. The other option is to only have one wire and either step down or up the voltage in the components that need it. The heat from stepping down 12v to 3 worries me and since most will be running of 3v it seems more logical and economical to use step ups when I need the 12v. Is this the best approach or is there another approach that I'm overlooking?
Most of the 12v components are buttons with built in leds so power consumption is pretty low, I guess they are mostly used in auto applications so most of the leds require 9-12v to light up well.