Audio Input Shield

(there’s an 8 pin header missing above)

Analog Envelope Follower
Arduino sound amplitude detector

Envelope follower is a common term for analog modular synthesizer users, by definition it’s “used to detect the amplitude variations of an incoming signal to produce a control signal that resembles those variations.” meaning that it follows the audio amplitude envelope creating a voltage output that resembles the audio signal volume, in this case between 0 and +5 volts

1 mono & 1 stereo 3.5mm jack input ( with individual volume* and decay** controls )
2 leds monitor each channel’s amplitude
Jumper selectable 2 mono channel analysis or 1 stereo analysis
Selectable analog inputs ( through two jumper cables you can route the outputs of the envelope followers to any analog input
Stackable shield

* volume works as an attenuator/amplifier for the incoming sound
** decay adjusts how quickly the voltage drops after a sound peak.

Code Examples
Linear Audio analysis
Logarithmic Audio analysis

Schematic & Board files
Download .zip file here>

The circuit used in this shield was inspired from a schematic by Tom Bugs of BugBrand