For my Christmas tree project i wanted to create a system which had a switch which operated various lights. Below is my System i created on Picaxe and below the finished product. I have also learnt that what I have created is a OPEN LOOP system Which has a start and finish, it is not continuous and there is no FEEDBACK. Had I used an LDR, Heat sensor or sound sensor instead of a switch this would have made my circuit a CLOSED LOOP circuit, as the circuit feeds back to these and determines where the start the process or stop the process depending on the conditions. For example I could put a heat sensor on my tree to flash when the temperature reaches below 10 degree's. If it reaches below 10 degrees the tree will flash until the temperature rises again then it will stop flashing.