bitmap@ucbtopaz.CC.Berkeley.ARPA (01/06/84)
Does anyone know how the anti-shoplifter detectors for books work? One person suggested to me that one type (where they warn pacemaker wearers) sends an rf(?) signal when the person goes through. Inside the book (?) is a small resonant circuit, which tends to reradiate (in many directions) when it picks up the original signal. This reradiated signal is then detected. How does the "demagnetizer" work (when they slap the back of the book on a plate, e.g.), and what does it do? Bill, UCB ucbvax!bitmap@ucbtopaz