The DIY RFID reader allows you read any EM4100 compatible tags. The RFID reader needs to be energized with a regulated 5V DC voltage (you can use a 7805 voltage regulator, Jameco P/N: 51262). Once the reader is energized, it is ready to read the UID from the compatible EM4100 Tag (Card, key fob, etc). The reading distance is about 7 cm. So when the tag is placed into the reading distance, the reader gets the tag's UID and then transmits it through serial interface at 9600 bps, 8bits, No parity and 1 stop bit. This serial interface is TTL true level, that means high level is 5V and low level is 0V.