Parts to build the solar sound module:
1 IC (typ 74HC14),
3 resistors,
3 capacitors,
1 solarmodul (2-3 Volt),
1 piezo-speaker.
The solar sound module circuit is designed with a Hex Inverter IC (Schmitt Trigger Type 74HC14). Every oscillator is assembled with two inverters, one resistor and one capacitor. The finished module has three oscillators, which compete for the unbuffered, lack energy of the solar cells. The variable sound pattern represent the internal astable switching conditions. The sounds are experimentally adjusted with alligator clips and different resistance and condenser values. The low energetic circuit concept permits this experimental approach.