So you've read it right. I had a capacitor designated 106J explode on my NODEMCU. It is this one:
Basically what I was trying to do is rotate a SG90 servo motor through my NODEMCU when it happened. The circuit is very simple. LiPo battery is connected to a step-up converter to bring 3.7V to 8V, which is then connected to the NODEMCU VIN and GND pins. Additionally, there is a 5V LDO hooked up after that step-up converter to provide 5V for the SG90. And there is a electrolytic 2200uF capacitor next to NODEMCU's VIN and GND. This capacitor is meant to smooth out the current for the NODEMCU due to the whole setup using single LiPo cell.
So, I hooked up the LiPo for the first time (previously I tested with a PSU), and noticed that the LiPo disengages immediately, because the 2200uF capacitor is too damn hungry, and exceeds the current that LiPo can supply in such a short time. So for the time being, I un-soldered the capacitor until I could figure it out. Without capacitor, LiPo was okay, and NODEMCU booted up nicely. So I gave it a command to run that SG90. And that when it happened. A LOUD, bright explosion. A burst of flame at least 5 centimeters long. Left flashes in my eyes for at least 10 minutes.
Upon inspecting the NODEMCU, I saw that the small 10uF capacitor designated 106J is now black and has massive holes on both sides of it. I replaced that 106J by scrapping another bricked NODEMCU, and now my primary NODEMCU is running fine again.
My question is, why did this happen? Did removing that 2200uF capacitor from the circuit cause some kind of an overload or a voltage spike that caused that little capacitor on the NODEMCU to explode? Again, I wasn't powering my SG90 directly from NODEMCU - I know that one should never do that - it was powered in parallel from LiPo, as I described earlier. So I can't understand how that SG90 could have caused damage to NODEMCU.
Do you have any ideas why this happened, and how to protect against it? Do I need some flyback diode or something?