Automatic thermostat device sounds with birdsong circuit

As shown in the figure, the circuit is composed of a thermal sensor head, a monostable trigger circuit, a birdsong sound circuit, and an AC step-down rectifier circuit. It can keep the electric heating device and its contents within a set temperature range. When the temperature inside the device drops to a given lower limit temperature due to heat dissipation, the electric heater will automatically turn on heating, and at the same time, it will also emit A few birdsong.