Make: More Electronics

Chapter 35. Experiment 35: The LFSR

Let’s suppose we have a black box containing some kind of circuit that generates a stream of numbers, without any influence from the environment. How would we decide if the stream is random? I think it should satisfy two requirements:

• The stream should be relatively free from repetition. I say “relatively” because any self-contained number generator will repeat itself if we allow it to run long enough. The objective is to create a sequence that is so lengthy or complicated, it exceeds the capabilities of human memory or attention span. (I am assuming that the number generator is on a large enough physical scale for quantum effects not to be relevant.)
• If we can specify a range of numeric values that are supposed ...