Automatic Lights

Tonight I designed and built two automatic lights. One of them switches a light on and off at regular intervals (a slow clock generator), another switches them on and off with an element of randomness (two slow clock generators and a logic gate). This is to give the impression of movement in a house -- one of the cheapest and simplest ways to deter burglars (one hopes). OBSERVATION: Both circuits failed when I first tested them. The problem lay in a crocodile clip, not in my work. I have often said, it is more important to know what went wrong than what went right.