This is DoorBell Bird Voice Electro Suite, to replace the old doorbell, to give the freshness in using the excitement new doorbell.
This suite will give the bird sound like a singing bird, the voice of bird managed by the C2. The duration of voice managed by C5, changing the C5 with the higher value will make the voice bird longer.
Power source is 12 Volt DC, the diode is 1N4001.