SD card shield not working on 3.3v My SD shield works nicely on 5v supply, but does not detect SD card on 3.3v. Could someone explain the possible reason behind this? Could you also provide a solution for this?

I've worked with it on Arduino Uno. Now I want to use SD card directly with ESP-12E to read its contents using SPI by doing something like this. Since ESP8266 operates olny on 3.3v, I need SD card to work on this voltage.

I've used two separate SD card shields without any luck! Photos of the two shields and micro-SD card are attached.
I could not find any info on the full size SD card adaptor, but the microSD adaptor has a 3.3V (LM1117 or equivalent) regulator on it. It, therefore, needs a minimum of 4.5V to operate.

To run the adaptor from 3.3V, you would have to remove the regulator and solder in a piece of wire in its place.