Do you wish to have a small and portable SD Card Read/Write with Arduino, but it’s somewhat costly to buy it from the RadioShack? Well, then just Do It Yourself and you definitely can cut off the budget cost for sure.
For today project, you must refer to the below schematic diagram.
As you’ve noticed that the above schematic uses some resistors in a voltage divider, and its main point is to bring down the Arduino 5V logic to the SD Cards 3v3 logic. By this way, all the outgoing signals from the Arduino will constantly dropped to 3v3. When the 3v3 is above logic 1 for the Arduino, then the incoming signals to the Arduino are fined. In other hand, the 3v3 voltage supply from the decimelia was normally used to supply power to the SD Card.
After the above step, make sure to desolder an SD Card socket from a broken memory card reader, and solder those pins onto the bottom. In addition, you have to ensure that the thermistor is perfectly connected to analog1 with some resistors for the testing purposes.