I am quite surprised this topic which repeats itself every day has not got a sticky like "Read before you wire your SDCARD shield" where somebody (ie. Nick) may summarize the steps necessary, with 3 scenarios (for example):
I agree. I think these topics need to be covered.
A review of shields/breakouts that work reliably without modification. Most users just want to use an SD in an app. This is the bulk of the mail I get about SdFat.
Edit: Power usage is important. I get a lot of mail about things like battery powered temperature loggers and how to reduce SD power. Good modules with level shifters and a recently designed SD card can draw less than 0.25 ma when idle.
How to build or modify an SD module. For those who want to learn and integrate an SD into their design.
The best way to fix a product. Fixing many of the bad products takes good skills, may cost more than buying a good module, and the result may not be acceptable. This is what a recent user decided about adding a level shifter to the LC Studio module.
I do agree with Constantin.
These days, any SD card board that uses the voltage divider approach of level shifting is a sign of a cheapskate/ignorant designer IMO - a sign which is ignored at your peril.
If you are going to learn, using a level shifter is no more difficult than resistors.
Adding three resistors may be the simplest way to fix the LC Studio card but still not great.