PaulRB:
Go with setting the convertor to 5V then, to keep MrMark and Wawa happy. It's less efficient and more energy will be uneccessarily wasted as heat in the Wemos' regulator, but apparently my idea too hazardous for novices.
I like the idea of using the onboard regulator, here in my city the power source are known for burning some home appliances and it is not easy to replace components here (2-3 weeks for replacement)
Wawa:
A TIP31 with 1k base resistor to drive a LED strip is not a smart move.
Driving that with a 3.3volt pin is even worse.A TIP120 with 330ohm base resistor could be much better (more light).
A mosfet is even better, assuming you can find one with low enough Vgs(th).
Leo..
Thank you for your suggestion. I am still having this problem of LEDs not bright enough.
Can you explain to me how to calculate the best resistor to use?
I have only TIP31 transistors and a couple of resistors (1k, 220, 480 and others I can't remember right now), I could get more but that will take a long time