Hehe, no actually its just a simple project that will enable me to learn few things. I don't intend to use it but maybe if it became that good, why not Right now i am just trying to amplify the voltage from microphone. Maybe once I master it use filtering. Since LM358 has maximum gain of 100, I should atleast get 10mv input. But the electret microphone only produce few hundred uV. So I guess getting 1V is impossible. Same goes to LM 386 which has a gain of maximum 200. So, i guess just getting 100mV output will do the job.
that gain will be provided at the lower end of the audio frequency range but not at the higher end
Seeing as you want to know when YOUR baby is crying, you should record him/her crying so you have a repeatable cry to tweak your filters that you have not yet implemented so the gadget you are building does not put your spouse in hommicide mode with you as the unlucky victim.To disambiguate my last statement... simply selecting a level for trip will drive your wifeee insane with nuisance trips from any noise....albeit the lawn mower next door, the front door opening and closing, ect. Filtering before the trip detection will allow you to tailor the heuristics of your preamp to match that of your baby's cry, thus making it less sensitive to ambient noises you don't want trips from. Such as dog shock collars are filtered for the unique content of a dog bark so the poor animal doesn't get a jolt when he scratches his head. (I owned a cheap one, it couldn't discern the clank of the d-ring from a bark, so the dog pretty much hid under the bed whenever the collar was on..)