This is a really simple sound effect generator based single sound generator chip UM3561. The UM3561 will generate four kinds of sound effects. The basic operation is that the UM3561 will generate the sound signal, then the signal delivered to 2N3706 (as speaker driver) to be amplified so you can hear the sound from a speaker.
Each switch position will generate the follofing sound effect:
- position 1 –> Police Siren
- position 2 –> Fire Engine Siren
- position 3 –> Ambulance Siren
- position 4 –> Machine Gun
Download the UM3561 datasheet for sound effect generator circuit reference:
? Download Link