How to build a simple but cool IR (Infra Red) receiver.

[-] What is the difference between a "NULL-MODEM" and a "straight" serial cable? It's simple. A NULL-MODEM cable is made to connect two computer by themselves. It has two female connectors and some wires inside are crossed to be connect the TX pin of one computer with the RX one of the other. This is not what we want for our receiver: we only need something to lengthen the link from the receiver to the serial port. A straight serial cable is depicted below: it has one female connector for the serial port and a male one for the receiver.