At least, I didn’t know about the Mellotron before last week. A lot of well known bands like The Beatles, The Bee Gees, The Rolling Stones, U2, Nine Inch Nails, Red Hot Chili Peppers etc. have used this device in one or more recordings. The Mellotron is a sort of organ with a bunch of cassette tapes in it. Every key on the organ is assigned an eight second sample which is immediately being played from tape when pressing a key/note on the organ. Actually it’s a sort of analog synthesizer/sampler. Very interesting device where you don’t hear that much about, you can even build one yourself using walkmans. See the following ad about the Mellotron and how it works: