Sound Level Detector

Thread Starter


Joined May 7, 2013
Hello ,
I need to do a project to check for ambient sound level, and if a sound abnormally exceeds that sound level it starts flashing a LED. I need to put a sound sensor(Microphone). when a sensor detects a loud noise, triggering a LED. Maybe I need another sensor to capture ambient sound too?
I have been checking the web all day,and I have came up with some not so clear ideas.
Any ideas?? Any suggestions?


Joined Sep 9, 2010
I think you'll need a 555-based timer to provide the LED flashing. I hear you can buy LEDs with a flasher built-in, so that would be a handy alternative if it meets your needs.

Then you need a comparator circuit with hysteresis that will latch to on if your sound level is exceeded. It will need a manual reset.

You'll need a way to convert the sound level to a voltage, and compare that to a preset voltage which you can establish by experiment. If you need a self-adjusting reference voltage that adjusts to the ambient level, that's more complicated.