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4 layers60 × 79 mmSpeaking clock smd, the printed circuit board in 3D

Speaking clock smd

lhm0/talking_clock1

A talking clock for visually impaired users. ESP32 controlled, fully offline, long battery life.

Size
60 × 79 mm
Copper layers
4
Thickness
1.61 mm
Parts
89
Nets
100
Pads
329
Tracks, vias
963, 294
Pours
2
Routed
Yes
KiCad
KiCad 9.0 (file 20241229)
Created
17 Feb 2026
Updated
20 Apr 2026

Overview

Speaking clock smd is an open-source printed circuit board by lhm0, from the lhm0/talking_clock repository on GitHub. It is a 4-layer board of 60 × 79 mm with 89 parts on 100 nets, routed with 963 tracks and 294 vias.

It is built around the ESP32-S3, TPS63070RNMR and W25Q128JVSIQ, with the DS3231MZ/V+, HEF4093BT and USBLC6-2SC6 among its other parts. Its parts include 31 capacitors, 28 resistors, 12 ICs, 4 connectors and 3 diodes. It belongs with the lEDs and displays boards and the ESP32 boards of this library.

Main components

10

README

README.md

Speaking Clock – Open Source Talking Clock for Visually Impaired Users

This repository contains an open-source talking clock designed for visually impaired and elderly users.

talking clock front

The device announces the current time at the press of a button.
If the button is pressed a second time within a short time window, it also announces the date.


🎬 Demo Video

Watch the demo video


📢 Native English speaker wanted!
Help improve the English voice output of this project → see below.

🔀 Hardware Versions

This project exists in two different hardware implementations:

🔹 Breakout Version (V1)

The original design based on breakout modules mounted on a carrier PCB.
This version is well suited for prototyping and easy assembly.

👉 Build instructions:
building_instructions_breakout_v1.md


🔹 Integrated PCB Version (V2)

A newer design with all electronics integrated on a single custom PCB.
This version is more compact, robust, and optimized for practical use.

👉 Build instructions:
building_instructions_integrated_v2.md


🧩 Project Overview

Both versions share the same core functionality:

  • Audio time announcement
  • Simple and accessible user interface
  • Fully offline operation (no internet required)
  • Low power consumption
  • Battery-powered design

The system is based on an ESP32-S3 microcontroller, uses a DS3231 real-time clock for accurate timekeeping, and plays pre-generated audio files via an I2S amplifier and speaker.


🛠 Development

The firmware was developed using Visual Studio Code [blocked] together with the PlatformIO [blocked] extension.

When uploading the firmware to the device, make sure to upload:

  • the main firmware (program code)
  • the LittleFS filesystem (audio data)

Both steps are required for correct operation.


🔊 Audio Files & Licensing

The speaking clock uses pre-recorded audio files to generate time and date announcements.

  • The German audio files were recorded manually for this project.
  • The English audio files were generated using a text-to-speech service (ttsMP3.com).

According to the ttsMP3 FAQ, these generated audio files may be used in both personal and commercial projects without restriction: https://ttsmp3.com/faq

The repository contains only the generated audio files, not the TTS software or voices themselves.

These audio files can therefore be:

  • Used in personal projects
  • Used in commercial projects
  • Shared and redistributed as part of other projects

Note: If you use this project, please verify the current licensing terms of ttsMP3.com to ensure ongoing compliance.

📢 Looking for a Native English Speaker

To improve the quality of the English time announcements, I am looking for a native English speaker who would be willing to record the audio prompts for this project.

The current English audio files are computer-generated and sound less natural than the manually recorded German version.

🎤 What is needed:

  • Clear and natural voice recordings
  • Short phrases (numbers, time expressions, weekdays, etc.)
  • Consistent pronunciation and pacing

📄 Requirements:

  • The recordings must be provided free of charge
  • They must be license-free or released for unrestricted use (including commercial use)
  • The contributor agrees that the recordings can be included in this open-source project

🙏 This would significantly improve the usability and user experience of the English version of the talking clock.

If you are interested in contributing, please open an issue or contact me via GitHub.

Parts

89
QtyValueFootprintReferences
12100nFCapacitor_SMD:C_0402_1005MetricC1, C2, C8, C10, C11, C13, C16, C19, C24, C27, C29, C31
710kResistor_SMD:R_0402_1005MetricR10, R11, R12, R13, R17, R18, R19
6100kResistor_SMD:R_0402_1005MetricR3, R20, R21, R22, R23, R28
50Resistor_SMD:R_0402_1005MetricR4, R5, R6, R7, R8
410µFCapacitor_SMD:C_0603_1608MetricC3, C18, C22, C23
41µFCapacitor_SMD:C_0402_1005MetricC9, C14, C15, C17
310µFCapacitor_SMD:C_0805_2012MetricC20, C21, C30
3~my_footprints:JLC_tooling_holeU20, U21, U22
210pFCapacitor_SMD:C_0402_1005MetricC4, C6
222µFCapacitor_SMD:C_0805_2012MetricC25, C26
22n2Inductor_SMD:L_0402_1005MetricL1, L2
23p3Capacitor_SMD:C_0402_1005MetricC5, C7
24k7Resistor_SMD:R_0402_1005MetricR15, R16
25k1Resistor_SMD:R_0402_1005MetricR1, R2
2AO3400APackage_TO_SOT_SMD:SOT-23Q2, Q3
2SS24Diode_SMD:D_SMAD1, D2
110nFCapacitor_SMD:C_0402_1005MetricC12
1150kCapacitor_SMD:C_0603_1608MetricR25
11kResistor_SMD:R_0603_1608MetricR26
11nFCapacitor_SMD:C_0603_1608MetricC28
12.2µHInductor_SMD:L_Bourns_SRP7028A_7.3x6.6mmL3
120kResistor_SMD:R_0402_1005MetricR14
122Resistor_SMD:R_0402_1005MetricR9
12k2Capacitor_SMD:C_0402_1005MetricR27
140 MHzmy_footprints:Crystal_SMD_4Pin_3.2x2.5mmY1
1470kCapacitor_SMD:C_0603_1608MetricR24
1CR2032my_footprints:Keytone_CR2032_holderBT1
1Conn_01x02_Pinmy_footprints:2_pinJ4
1Conn_01x02_PinConnector_JST:JST_XH_B2B-XH-A_1x02_P2.50mm_VerticalJ2
1Conn_01x03_Pinmy_footprints:3_pin_jumperJ3
1DS3231MZPackage_SO:SOIC-8_3.9x4.9mm_P1.27mmU8
1ESP32-S3my_footprints:IC_ESP32-S3U4
1HEF4093BPackage_SO:SOIC-14_3.9x8.7mm_P1.27mmU6
1IRLML6401Package_TO_SOT_SMD:SOT-23Q1
1LEDLED_SMD:LED_0603_1608MetricD3
1MAX98357APackage_DFN_QFN:TQFN-16-1EP_3x3mm_P0.5mm_EP1.23x1.23mmU9
1TPS63070RNMRmy_footprints:VREG_TPS63070RNMRU7
1USBLC6-2SC6Package_TO_SOT_SMD:SOT-23-6U2
1USB_C_Receptacle_USB2.0my_footprints:USB_C_ReceptacleJ1
1W25Q128JVSPackage_SO:SOIC-8_5.3x5.3mm_P1.27mmU1
1WiFi antennamy_footprints:PCB_antennaU3
1configmy_footprints:OmronTasterSW3
1resetmy_footprints:C720477SW1
1volume_knobRotary_Encoder:RotaryEncoder_Alps_EC11E-Switch_Vertical_H20mmSW2
1~my_footprints:1pinU5

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Questions

How big is the Speaking clock smd PCB?

It measures 60 × 79 mm and has 4 copper layers, 1.61 mm thick.

What parts does the Speaking clock smd use?

89 parts, built around the ESP32-S3, TPS63070RNMR, W25Q128JVSIQ and DS3231MZ/V+. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Speaking clock smd KiCad files?

From the lhm0/talking_clock repository on GitHub, at the commit this page was made from: the board is hardware/integrated_v2/electronics/speaking_clock_smd.kicad_pcb and its schematic hardware/breakout_v1/electronics/speaking_clock.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Speaking clock smd design in my own project?

Its repository states no licence, so its author keeps all rights: ask lhm0 before reusing the design.