I need to build one that can be used outdoors.

Where can I find the schematics for this kind of circuits?

For clarification

I need to assemble a few random sound generators that can act as a sort of electronic scarecrows, but with enough capability to be able to produce sounds like footsteps, short whistles and other human common sounds.

There is no need for high definition or very wide range, as the circuits are to be placed outdoors, in a plot of land I own, and having more scattered throughout the area will be more effective than just having one or two sound sources that can be easily pinpointed.

The place is often broken into by dogs that have destroyed crops and even killed animals. These are dogs that avoid/flee from human beings and I want to use that to deincentivize them go to the place.

Ideally, these circuits are to have the smallest footprint possible, in order to be capable of being powered by a 9V battery or perhaps a small lithium rechargeable.