2 layers90 × 44 mm
Nixie main
snakeye/nixie-clock
Nixie clock based on ESP32-C3 Super Mini module and Soviet IN-14 tubes
12 parts
2 layers90 × 44 mm
Nixie clock
snakeye/nixie-clockNixie clock based on ESP32-C3 Super Mini module and Soviet IN-14 tubes
- Size
- 90 × 44 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 22
- Nets
- 46
- Pads
- 128
- Tracks, vias
- 493, 9
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 18 Mar 2020
- Updated
- 25 Jul 2026
Overview
Nixie clock is an open-source printed circuit board by snakeye, from the snakeye/nixie-clock repository on GitHub. It is a 2-layer board of 90 × 44 mm with 22 parts on 46 nets, routed with 493 tracks and 9 vias.
It is built around the TLP627(F) and 74HC595. Its parts include 8 resistors, 6 ICs, 2 capacitors and 2 connectors. It belongs with the lEDs and displays boards and the ESP32 and RISC-V boards of this library.
Main components
2
TLP627(F)
DIP-4-55℃~+100℃ 1 1.15V 1.2V@100mA,10mA 150mA 15us@10mA,100Ω 300V 40us@10mA,100Ω 5kV DC Darlington Transistor DIP-4 Transistor, Photovoltaic Output Optoisolators ROHSToshibaTransistor, Photovoltaic Output Optoisolators
74HC595
SOP-16-40℃~+85℃ 1 100ns@5V,50pF 10MHz 2V~6V 74HC 8 Serial-to-Serial or Parallel Tri-State SOP-16 Shift Registers ROHSGRShift Registers
README
README.mdNixie 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-C3hardware/main/- main KiCad project for the clock boardhardware/indicators/- indicator-board KiCad projectdocs/- photos and other documentation assets
Firmware setup
- Open
firmware/in PlatformIO or your preferred VS Code setup. - Copy
firmware/src/config.h.exampletofirmware/src/config.h. - Fill in your Wi-Fi SSID and password.
- Build and upload the
esp32c3environment.
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.his ignored by Git so local Wi-Fi credentials stay machine-specific.
Parts
22| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | 22K | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R2, R4, R6, R8 |
| 4 | 390 | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R1, R3, R5, R7 |
| 4 | IN-14 | nixies-us:nixies-us-IN-14 | N1, N2, N3, N4 |
| 4 | TLP627 | Package_DIP:DIP-4_W7.62mm | U2, U3, U4, U5 |
| 2 | 0.1uF | Capacitor_SMD:C_0805_2012Metric | C1, C2 |
| 1 | 155ID1 | Package_DIP:DIP-16_W7.62mm | U6 |
| 1 | 74HC595 | Package_SO:SOP-16_4.4x10.4mm_P1.27mm | U1 |
| 1 | HV | Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical | J1 |
| 1 | MCU | Connector_PinSocket_2.54mm:PinSocket_1x06_P2.54mm_Vertical | J2 |
Questions
How big is the Nixie clock PCB?
It measures 90 × 44 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Nixie clock use?
22 parts, built around the TLP627(F) and 74HC595. 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 Nixie clock KiCad files?
From the snakeye/nixie-clock repository on GitHub, at the commit this page was made from: the board is hardware/indicators/nixie-clock.kicad_pcb and its schematic hardware/indicators/nixie-clock.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Nixie clock design in my own project?
Its repository states no licence, so its author keeps all rights: ask snakeye before reusing the design.
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