Remember the holophonor from Futurama? It was (will be?) a musical instrument that would project holograms depending on the mood of the note played.

Being a futuristic instrument, the inner workings of the holophonor are unknown. However, the basic idea of being able to detect the frequency of musical notes is something we can possibly emulate. And that is what we'll explore in this guide using a fairly simple technique.

We'll also use the frequency detection to drive NeoPixels (our version of the holophonor) and also show how a TFT Gizmo can be used to display the note information.

Which Circuit Playground?

The technique used here to estimate the audio frequency is fairly simple. It relies on constantly sampling the microphone and analyzing the results. Therefore, the more powerful the processor, the better.

We've found that this works best on the Circuit Playground Bluefruit. You can also run it on the Circuit Playground Express.


The following parts are used in this project:

shot of a Black woman's neon-green manicured hand holding up a Circuit Playground Bluefruit glowing rainbow LEDs.
Circuit Playground Bluefruit is our third board in the Circuit Playground series, another step towards a perfect introduction to electronics and programming. We've...
Hand pressing buttons on circuit playground, then turning over to show TFT gizmo display an image of a friendly robot or snake
Extend and expand your Circuit Playground projects with a bolt on TFT Gizmo that lets you add a lovely color display in a sturdy and reliable fashion. This PCB looks just like a round...
USB cable - USB A to Micro-B - 3 foot long
This here is your standard A to micro-B USB cable, for USB 1.1 or 2.0. Perfect for connecting a PC to your Metro, Feather, Raspberry Pi or other dev-board or...

This guide was first published on Oct 22, 2019. It was last updated on Jul 15, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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