I made a happy discovery in a trunk today: my original Pitch Switch, covered in fine dust, which I designed for a publisher in the UK. This was a popular design at the time. I tuned the prototype to trigger a switch in Cape Town when someone blew a trumpet in a stadium in the Caribbean, during a sports broadcast. It filtered out everything but that trumpet. OBSERVATION: I said to the publisher, Isn't this potentially dangerous? One could murder someone at the other side of the world with the blast of a trumpet in a sports stadium, and no one would ever know. He said, No, anyone could do that today, with a middling ability in electronics.