Show HN: I built a synth for my daughter

Summary

TLDR: I built a portable step-sequencer synthesizer for my daughter’s third birthday. It has four sliders that control four notes in a looping sequence. Slide up = higher pitch, slide down = lower. It includes: An onboard synth module + speaker Tempo, volume, scale, pitch, and instrument controls An OLED screen with visual feedback + a dancing panda A custom PCB and 3D-printed enclosure It's a child-friendly, tactile music toy. Here's the pink edition in action: VIDEO Why I built this My daughter received a Montessori activity board full of switches and LEDs for her first birthday. Watching her twist knobs and flip the switches reminded me of the control surface of a synth, and I wondered if I could build a musical version - something simple, tactile, and creative that didn’t require holding down buttons to keep the sound going. A year later I finally decided to build it. I had no prior hardware experience, so this became an excuse to learn about microcontrollers, CAD, PCB design, and 3D printing. First steps I started the project with a 15 year old Arduino Inventors Kit and only a vague idea about how to use it. The first goal was simple: build a basic MIDI controller on a breadboard. If I could get some potentiometer readings, map them to 12 discrete values - one for each note in an octave - and emit MIDI messages, I would have taken a small step in the right direction. Adding an onboard synth module and designing a pretty box to put it in could wait until later. Reading the potentiometer inputs and turning them into the MIDI messages using the Arduino MIDI library was easy enough. To hear the output, I wrote a small Python script that intercepted the MIDI messages and forwarded them to my Mac’s default MIDI device, which Logic Pro could pick up. That let me “play” the breadboard through software instruments. Once I had the hang of wiring up potentiometers and rotary encoders, the next step was to move the audio synthesis from Logic to my breadboard. For this I us...