Light Music

Derived from /

At the heart of this circuit is the UM66 IC, a sound generator. The IC is a CMOS LSI designed for using in door bell, telephone and toy application. When light shines on the LDR, the resistance drops and sends a signal to the T1 transistor. Power flows through the transistor to the UM66 musical integrated circuit, and a note will be amplified by transistor T2 and fed into the 8Ω speaker. T3 turns on a DC motor. The IC is preprogrammed to generate certain frequencies. When powered, the melody generator is reset and melody begins from the first note.