hello i have asked assistance on MP based projects and i was suggested to start from the basic circuit. so i decided to do an IR detection system... I need help in understanding 1. modulation technique to generate IR. (I know about AM, FM and other digital modulation techniques but which to use?) 2. power conservation and power failure avoiding techniques. ( I don't know anything about them) 3. how to use photo diodes? the only transistors i have worked with are BC107 and BC108. i know nothing about scr, thyristor or triac/diac characteristics and where to use them... although i can read these info in books i will still not know their practical application... can any one help a lay man like me?