This peak detector is quite simple:
- aÂ LM386Â acts as aÂ preampÂ for the electret microphone
- a first part of a (hard-to-find and expensive)Â OPA2277-PAÂ handles adjustment of theÂ sensitivity
- another part of a (hard-to-find and expensive)Â OPA2277-PAÂ handlesÂ comparisonsÂ andÂ triggersÂ the output level: 0V means “no sound”, +5V means “hey I got a sound”.
If I can get something from the LM386 output (tested with a multimeter andÂ SirProbe), nothing from the OPA2277 output. I think this sensor must be build on a real board to avoid any contact failure, and tested with a real oscilloscope…