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 ...

This circuit enables the on/off times of a 555 timer to be independently varied over a wide range. This is not possible with a conventional 555 circuit with the RC network being charged from the ...

A running joke we see in the comments by Hackaday readers whenever a project includes an Arduino or Raspberry Pi that seems like overkill is to proclaim that “I could have done it with a 555 timer!” ...