Audio sensors (read: microphones) connect to an Arduino. When the sensors create an audio signal (when the mics are hit) they trigger a MIDI note – generated by the Arduino – which is sent to a drum machine.


Trigger drums from piezo sensors.


These super cheap microphones have horrible sound quality, but they are great at detecting sound.

Piezo sensor
Piezo sensor


Each drum instrument (snare, kick, cymbals, etc) is assigned a piezo, and each piezo is connected to an input pin on the Arduino. All eight of ’em are wired up and labeled with their instrument name and associated Arduino pin.

Sensors w/labels
Sensors with labels


An Arduino MEGA 2560 – the UNO’s big brother – is chosen because of the extra analog inputs. Analog inputs allow different levels to be sensed (based on the strength of the hit on the piezo) to let the Arduino generate a different velocity of note.

MEGA 2560
MEGA 2560 with shield


The MIDI signal is output through a standard MIDI connector, and can connect to anything which supports MIDI – keyboards, DAWs, drum machines, etc.

MIDI connector


The sensors can be hooked up to pots and pans, cardboard boxes – anything!


Here they are taped to an traditional acoustic drum kit.

Drum kit
Drum kit with sensors


The code specifies which MIDI notes will be triggered, and also allows threshold calibration for each sensor.