Introduction to the Principle of Music Integrated Circuit

Introduction to the Principle of Music Integrated Circuit

Using music integrated circuits, you can get simple music, voice or various simulated sounds through simple external circuits. Music integrated circuits are cheap, simple in circuit structure, stable and reliable in operation, and low in power consumption, so they are widely used; they can be seen in music doorbells, music New Year cards, music clocks, and telephone ringing circuits. Music integrated circuits
are a large-scale CMOS integrated circuit. The internal structure block diagram of a music integrated circuit is as follows:

 The signal generated by the oscillation circuit is used by each circuit; the control circuit reads the code from the memory, and controls the metronome and tuner to work in coordination according to the code to produce the corresponding music output.
Music integrated circuits generally use "soft packaging", some use dual-in-line and single-in-line packaging, and some are made into a crystal triode shape, called "music triode". The working voltage is generally 1.5 to 3 volts DC power supply.
Piezoelectric ceramics are often used as electro-acoustic conversion devices for output; crystal triodes are also often used to amplify and send to speakers for playback, which has better sound quality.

The schematic diagram of the bird call simulation circuit is as follows: 
 
　

The integrated circuit has 5 pins 1, 2, 3, 4, 5, and their functions are: 1 - positive power supply 2 - trigger 3 - original audio output 4 - amplified audio output 5 - negative power supply Function of capacitor C: Capacitor C is a ceramic capacitor with a capacitance of 0.01 microfarads. The "103" in brackets in the figure is another way of representation, which means "10" followed by 3 zeros, that is, "10000". The default unit of this representation is "picofarad"; 1 microfarad = 1000000 microfarads. Therefore, "0.01" microfarad = "103" microfarads. 




 
 

C is used to prevent the self-excitation of the transistor BG (9014). Sometimes, the circuit is made completely correctly, but the speaker is silent. At that time, it is better to add capacitor C. This is because the transistor has a large amplification factor, which produces self-excitation and suppresses it. Therefore, when the amplification factor of BG (9014) is small, C can be omitted.