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 circuit was found in an English documentation from the 90's. Equivalent components such as...
This circuit was found in an Electronics Now of the 80s applying to NiCad batteries of the time....
The pulses applied to input C of the SAA1027 integrated circuit determine the engine speed. Each...