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.
We found this amplifier circuit for inductive audio pickups in a documentation from the 70s. The...
The presented circuit uses two old germanium transistors. We found this configuration in a...
This high stability circuit was found in old documentation. The operational can be a modern...