For Salah The site Victor gave you has excellent info in IR transmission. However, the thing about IR is that transmission must be in a straight line and both the receiver and transmitter must remain in a fixed position for reliable communication. RF does not have these restrictions. Sid -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body