Aetherharp-4 MIDI Air Piano

The Aetherharp-4 is a music instrument with 8 virtual keys with infrared distance sensors. The keys are activated by moving your hands above these sensors and you can play 8 notes in 6 octaves. the information from the sensors is transmitted to a PC/laptop via the MIDi protocol with 128 selectable instruments.

This Aetherharp-4 is an update on the previous version Aetherharp-3.

In this instructable I describe the updates only.

These updates are:

The note indication LEDs.

The internal wiring.

The grounding system.

The software.

The case, the internal computer (a Teensy 3.5) and the control buttons, switches and display are exactly the same as described in version 3.

For the construction and details of version 3 see here: Aetherharp-3 : 6 Steps (with Pictures) - Instructables

How to use the new Aetherharp-4 is descibed in the attached user manual.

See the attached PDF document for the components and tools needed for the Aetherharp-4.

The LEDs are mounted on a small cardboard strip and placed inside a plastic cable tray mounted on top of the cable tray with the sensor wiring.

Each LED has two connections (red and blue, connected to the digital output pins of the Teensy 3.5) and a common wire connected via a 220 Ohm resistor to GND.

The wiring is updated with the connections for the bicolor LEDs. The octave Up/Down buttons are relocated to other pins on the Teensy 3.5. The ground connection from the external power supply for the analog infrared sensors is now separated from the other ground connections. This minimizes noise from the digital components. This ground is now connected to the AGND pin from the Teensy 3.5. This pin is connected to the normal GND via an internal noise filter.

See the diagram for all details.

Outliers from the sensor readings are now minimized via the runningmedian library.

Each loop of the program one reading is added to an array of 10 and the oldest one is deleted.

Then the median value is selected to play a tone.

When the distance from your hand to a sensor is 5 cm. or less, the tone played is lowered one octave and the red LED is activated instead of the blue one.

If you want to experiment with other notes:

See the octave chart and the chart with the USB MIDI numbers versus the music notes.