I have a very cheap SD card board from Futurlec, but it had a very unstable SD connector. Consequently, most of the times I could only connecto the SD card when I push the card in the holder with my fingers. Therefore I made a new board. Luckily I had a SD card connector left from a school project from some years ago.
The board consists of:
- 3.3V regulator for 5V->3.3V
- CD4050 buffer, powered at 3.3V. It is used as level shifter for chip select,MOSI and SCK. The MISO is connector directly from the SD card to the arduino.
- power LED
Because I made some mistakes, the soldering work is a big mess. But what mathers: it works. I had a 32MB SD card left from a Canon digital camera. It was standard formatted in FAT12, so I had to reformat it in FAT16 to make it work with the arduino library.