Use 5V SD-Adapter on 3.3V System I want to use a Catalex Micro SD Card Adapter in Combination with my Arduino MKR GSM 1400. The problem is, that the Arduino uses 3.3V to operate but the SD Adapter needs 5V (or at least 4.5V) to operate properly. Can I just use the 5V output of my Arduino to power the adapter, or will a higher voltage destroy the arduino when using it over a longer period of time? And if so, how can I use my MKR GSM 1400 with a SD-module? Maybe by unsing a step up/down converter in my circuit or just switch to a module that uses 3.3V?
The SD card is a 3.3 V device. The 5 V module with SD card adapter steps down the voltage for powering the card and has logic level conversion for card's SPI pins.

If you want to connect SD card to a 3.3 V board it is better to use a simple breakout board without power and signal conversion.

I do not recommend you to connect a 5 V SPI device to MKR SPI pins without logic level conversion.

EDIT: smajli analyzed in his answer the logic level conversion chip used on the adapter you use. it doesn't output more than 3.3 V and you can use it powered from 5 V. but it is still a workaround.