2. Circuit principle

Whole circuit with a 9561 tones of integrated circuits as the core, with four binary code to encode 9561 working condition control, make its produce 16 different analog sound. The whole circuit including noise generation circuit, basic additional control circuit and control circuit, the binary coding circuit and so much.

1. Sound generating circuit, U2 9561 with transistor Q1 and passive buzzer LS1.

2. Basic control circuits, with two binary digital control U3 of two selected the four kinds of working condition, make its produce four basic acoustics as required.

3. The additional control circuit, using the four states of two binary digital resistor R1, R2, R4, R5 produce a combination of four different to change 9561 external vibration resistance value, which changes the oscillation parameters, the change of the oscillation parameters, is not only changed the oscillation frequency, and derive a lot of new sound.

Combine basic control circuit and the additional control circuit, constitute A complete control circuit, is controlled by A B C D four binary encoding, make 9561 produce 16 different sounds.

4. The binary encoder circuit, the switch S1 - S4, resistance R6 - R9 etc binary encoder. S1, S2, S3, S4, corresponding binary digital A, B, C, D four. Switch to stir to 0, switch to stir to 1. Make up A, B, C, D four binary digital voice through control part 9561.