Typical working principle diagram of HY8010 and HY8020 circuits

Figure a is a typical working principle diagram of the HY8010 and HY8020 circuits. An external transistor is connected to the circuit to drive the speaker, and the output power is within 50mW. Choose 9013 and other low-power transistors with β≥150. SP chooses 8Ω impedance and 1/4W speaker. Rosc in the figure is an external oscillation resistor, and the external resistor adjusts the sampling frequency. The Rosc resistance value of HY8010 is selected between 90kΩ and 300kΩ, and the Rosc resistance value of HY8020 and HY8040 is selected between 470kΩ and 2MΩ. Changing the resistance value can change the playback speed to meet normal requirements. In Figure b, the piezoelectric buzzer circuit is directly driven (the resonant frequency of the piezoelectric buzzer is 1kHz). Mainly used in electronic letters, voice greeting cards and other smaller products.