fig. 1 is a circuit diagram. Music IC is usually packaged directly on a small (about 22mm×15mm) printed circuit board, with five pins connected to the printed circuit board, and battery clips, switches, etc. are all installed on the board. This is a music IC assembly consisting of a music IC board and a piezoelectric buzzer with a sound-assisted cavity, which is usually called a music electronic movement. It is mainly used for manufacturing various electronic music cards. The power supply voltage of the circuit in Figure 1 is 1.5 ~ 3V, which can be supplied by one or two G13 button batteries. The switch S is a special displacement switch. A plastic piece is sandwiched between two metal pieces of the switch, and one end of the plastic piece is stuck to one side of the paper card. When the greeting card is opened or closed, the switch S will automatically control the power supply of the music electronic movement. Fig. 2 is a physical diagram of a music electronic movement. The method and steps of making electronic greeting cards are as follows: ① Choose a beautiful card with 3% discount (or make it by hand). ② Pull out the plastic spacer in Figure 2 horizontally, and then fold the self-adhesive water paper pad of the electronic movement by 18 along the dotted line (the plastic sheet must not be folded together). ③ Spread the greeting card, align the dotted line of the electronic movement with the folding line in the middle of the greeting card and stick it firmly. When the greeting card is opened, the plastic sheet is pulled out from the horizontal direction, the switch is turned on, and the buzzer sounds music; When it is closed, the plastic sheet is pushed in, the switch is turned off, and the music stops immediately. At this time, a delicate music greeting card is ready. Acousto-optic music card Figure 3 is a circuit diagram of a music electronic movement that can drive four light-emitting diodes (LEDs 1-4). Fig. 4 is an entity diagram. Comparing Figure 3 with Figure 1, we can see that there are only four LEDs in Figure 3. When the switch S is turned on, the LED flashes and glows synchronously with the cheerful music sound. LED1～LED4 can choose light-emitting diodes with φ3, low power consumption and different colors and shapes. The circuit must be powered by two 1.5V G13 button batteries. The method and steps of making greeting cards are the same as above.