As shown constituting the photoelectric conversion by the photoelectric sensors and switches 555, etc., issued by a music song to prompt IC2. Illuminance sensor parts are made
of photovoltaic cells 2CR33. When light is lower than the most suitable for learning 100 lux illumination, 2CR33 was high resistance, VT1 off nearly 555 was 2 feet high (greater than 1/3Vdd 2V), 555 in the reset state, 3 feet was low, music IC2 (9300) issued by the sound of music was electric. When debugging, the 15W light bulb for the light from the lamp 0.3m battery in place, its illumination of about 100 lux. Adjust RP1, make 9300 just does not sound, shifting slightly farther away, the sound.