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.
Timer based would be fine.
OK. So I think you have your answer. Case, board, battery, timer circuit, tone generator. Look these up on the web. Lot of them will be based on the 555 timer chip. A common electronics store is Jameco and Newark. There are other sound chips too but I am not familiar with the numbers. Simple oscillators do not actually need an IC, could probably just be discrete. Keep in mind to electronics do have temperature ranges, performance of whatever you design will have to be tested at different temperatures.
More realistic sounds, I think that gets harder fast. To do that you’d have to in the end record sounds into a PROM and read it out though a DtoA. Or use an SBC and program it.
Historically there were sound generator chips like: https://en.wikipedia.org/wiki/Texas_Instruments_SN76477 . Not sure if these are even made any more. Again the sounds were crude.