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 for experimental radios and other applications is from a documentation from the 50's....
This third-order filter was found in a 1975 publication. The circuit must be powered by a...
This circuit was found in an Elektor from the 90s. The integrated circuits are not very common...