The UM66 series are CMOS IIC’s designed for using in calling bell, phone and toys. It has a built in ROM programs for playing music. The device has very low power consumption. Thanks for the CMOS technology. The melody will be available at pin 3 of UM66 and here it is amplified by using Q1 to drive the speaker. Resistor R1 limits the base current of Q1 within the safe values. Capacitor C1 is meant for noise suppression.

Notes

• Power supply must be between 1.5V & 4.5V .Do not exceed 4.5 V.
• Speaker can be driven with external NPN transistor.
• Melody begins from the first note if power is reseted.
• Assemble the circuit on a good quality common board.
• If transistor HE8050S is not available use any NPN transistor like BC548 or 2N2222.

Supplier link: https://www.electroschematics.com/wp-content/uploads/2011/04/um66t-datasheet.pdf

NOTE: ZL66, UM66, FT66 and TA66 are equivalents of same IC from different manufacturers