Nixie main

Nixie Clock

An ESP32-C3 powered Nixie clock built around custom KiCad hardware and Arduino firmware.

Boards

Main board

Indicator board

What this is

This repository contains the hardware and firmware for a four-digit Nixie clock. It uses Wi-Fi to sync time from NTP, drives the tubes with a multiplexed display stage, and keeps the high-voltage supply disabled until the clock has a valid time.

Features

• Wi-Fi time sync via NTP
• Automatic high-voltage safety control
• OTA firmware updates
• Manual cathode cleaning from a button long-press
• Automatic daily cathode cleaning at midnight
• KiCad hardware for the main clock board and indicator board

Key components

• IN-14 Nixie tubes
• 155ИД1 high-voltage digit driver
• ESP32-C3 SuperMini module
• 74HC595 shift register
• TLP627 optocouplers
• Nixie Tube Boost Converter module
• WS2812B RGB status LED
• USB-C power input
• Two push buttons

High-voltage boost module

I've used this particular module found on AliExpress. It features voltage adjustment. Other modules should also work, but they'll require proper wiring.

How it works

The firmware boots in a safe state with the display blanked and the high-voltage rail off. After Wi-Fi connects and NTP provides a valid time, the clock enables the high-voltage section and starts showing the current time.

When a successful sync happens, the firmware opens a short OTA maintenance window. If an upload starts, the high-voltage rail is disabled while the update is in progress.

Button 1 has a long-press action that starts cathode cleaning manually. The same cleaning routine also runs automatically once per day when the clock reaches midnight.

Repository layout

• firmware/ - PlatformIO project for the ESP32-C3
• hardware/main/ - main KiCad project for the clock board
• hardware/indicators/ - indicator-board KiCad project
• docs/ - photos and other documentation assets

Firmware setup

1. Open firmware/ in PlatformIO or your preferred VS Code setup.
2. Copy firmware/src/config.h.example to firmware/src/config.h.
3. Fill in your Wi-Fi SSID and password.
4. Build and upload the esp32c3 environment.

The firmware is configured for the esp32-c3-devkitm-1 board.

Notes

• The clock currently uses a CET/CEST timezone definition in firmware.
• The firmware hostname is nixie-clock.
• firmware/src/config.h is ignored by Git so local Wi-Fi credentials stay machine-specific.