This circuit that generates a special sound was found in a Popular Electronics from the 90s. The base is the 555 and the transistors admit equivalents, and a power stage can be added.
This is one of the many approaches we have on the site for this low power 0.5 W amp using the...
This circuit simulates an American siren and can be found elsewhere on this website and section....
This 80's amplifier delivers 6 W of 8 ohm speaker power without using an output transformer....