This is one of the many possible siren configurations for the 555 integrated circuit. We found it in the October 1992 Radio Electronics magazine. It has a power stage.
This interesting source, obtained in a 2001 catalog, can vary the output voltage between -16 and...
The LS4558 integrated circuit is a double 741. The filter response curve is given next to the...
This filter is from the Linear Applications Handbook of the National Semiconductor of 1994....