This is a simple circuit which produces a sound similar to the police siren and is built using NE555 Timer. Two 555 timers act as an astable multivibrator. Here is the simple circuit designed to ...
Whenever I use the 555 timer, it seems that the output polarity is invariably incorrect, and the way the 555 functions, it normally cannot generate a duty cycle of less than 50% — 90% yes, 10% NO!