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 the normal configuration of a stable or CMOS oscillator with NAND gates. This...
This setting appears with variations at various points on this site. This is from a Motorola...
Suggested by the 90s ARRL Handbook edition, this circuit aims to reduce or cancel noise at the...