Q: What patents are related to the 555?<p>A: There are no patents on the 555. Signetics did not want to apply for a patent. You see, the situation with patents in Silicon Valley in 1970 was entirely different than it is now. Everybody was stealing from everybody else. I designed the 555 Signetics produced it, and six months, or before a year later, National had it, Fairchild had it, and nobody paid any attention to patents. The people at Signetics told me they didn’t want to apply for a patent, because what would happen if they tried to enforce that patent, is the people from Fairchild would come back with a Manhattan-sized telephone book and say “These are our patents, now let’s see what you’re violating”. It was a house of cards – if you blew on it, the whole thing collapsed. It took about ten years to change. I guess it was some new companies that didn’t have ancient history and did have a strong patent, and started enforcing, and that changed to whole situation. It is very intense now. The same thing – I have a patent on the phase locked loop, and that would have been a very strong patent, but no enforcement.