A while ago I have bought NodeMCU board along with few sensors to play with. I have coded everything, and, when powered via USB, works like a charm. Problem begins, when I try to use my contraption as a standalone system. It works for few minutes, then it starts giving me false readings from the sensors (like, luminosity of few thousands in a dark room).
I am powering the system with (pics at the bottom of the post) AC-DC step down module, 230v -> 5v (1A of current), which then I am stepping down with DC-DC step down module, 5v -> 3v (800mA of current). Using only these two modules, I power NodeMCU and all of my sensors - currently luminosity, temp&humid, motion, SSR (I had led matrix too. I thought that maybe it drags too much current, but no luck there - after disconnecting it I have same problems).
My main indicator that something is not right, is SSR module. It has a built-in diode of the same size that NodeMCU has. It lights immediately as I start the system, and it (it's diode) flickers (it's intensity changes). It does not flicker, when I connect everything through USB.
I have also tried to put 50uF capacitor into the wiring, but no luck either, system is still unstable. What am I doing wrong? Why does the light flickers? Is 1A/800mA not enough power for my system?
Edit: I know what is the cause. I just do not know how to fix it. I just kept my multimeter on for 10mins for both of the step down modules. 5V -> 3V step down (2nd item in the pics below) is initially giving me 800mA, but then gradually losing current (right now it's at 350mA after just few minutes of work). Is there anything I can do here? Or just throw the thing away and look for some other power supply? It's a standard AMS 1117 with some capacitors on it.
Below are the pictures, of my step-down modules and SSR module: