Pocket Drum Machine / Sequencer

Bite sized beats!

Overview:

This project is a simplified version of Teenage Engineering's Pocket Operator, a calculator-sized sampler/sequencer.

Description:

This project consists of a keyboard input array which can be mapped to notes and played over an audio output.

Features:

ESP32 WROOM 32E and ESP32S2 microcontroller compatibility
Headphone jack/built-in speaker switching with parallel DAC+AMP ICs
Mini LCD screen for visualization
Analog/discrete control (key inputs & potentiometer dials)

Digital filtering/delay effects (planned)

Design:

Block Diagram

Bill of Materials

Completed Schematic

Layout (top layer)

Layout (bottom layer)

Completed layout

3D Render (1)

3D Render (2)

Assembly:

Base PCB.

We didn't get two LCD screens, so we were only able to produce one complete copy of the board.

We realized later on that we had mistakenly used a decoder instead of a mux for button input - had to use pull-down input, which meant we could only read from 4 lines.

We ordered >12 buttons for an octave of notes, but switched to drums instead.

Ordered 0603 metric (0201) so was forced to engage in some cursed soldering (see C3, C13, C14).

(cursed soldering, continued)

Finished board - front (no LCD/mux yet)

Finished board - back

Completed board (with display) at soldering station

Completed Board

Lessons Learned:

Triple check the schematic and part names
Use reflow oven / heat gun BEFORE placing plastic parts
Do not hand-solder the ESP32 (tempting due to large pads)
Hey, maybe getting the board assembled for you isn't so bad

Page updated

Report abuse