Even in the digital age of Smart phones, people do like to mail out or hand over greeting cards along with gifts, to celebrate an occasion or to express a sentiment. Some greeting cards play music or sound when they are opened and these are handmade cards which play traditional celebration songs using an embedded PCB which does the job. Obviously the song should be played only when the card is opened, and this is achieved with a tiny flat magnet and a sensor mounted inside the card, under the glued on paper flap. Ultra miniature reed switches or tiny Magnetic Proximity Sensors are used in musical greeting cards with appropriate magnets, to play a tune whenever the card is opened. Compared to the additional circuitry for the musical tones and the speaker, the reed switch bulk is much less. Normally open or Normally Closed versions can be used.