Arduino Nano 33 IoT Modular Nixie Clock with WebUI

USB 5V or 12V, Motion, Light, Temperature, Humidity & Pressure Sensors. NTP Sync, Web Interface for changing settings/time & wifi.

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I'm a bit late to the Nixie Party but I finally made it here.

This Nixie Clock is a bit different from the others; it runs using an Arduino Nano 33 IoT, has a motion sensor, light sensor, temperature, humidity & barometric pressure sensor and runs from 5V USB or 12V.

It has a web interface for changing settings and syncs the time using NTP.

Before I got to the final product, I had spent a lot of time making a Shift Register version with transistors and multiplexing, this worked on the breadboard however I got severe ghosting when I made the PCBs. I gave up and switched over to the HV5530 IC which simplifies things.

*** Caution the PSU can output high DC voltages, can cause serious injury ***

Features and design

The clock has been made to be as modular as possible, the PCBs consist of a main Nixie board, Arduino Nano board with DS3231 and 12V boost convertor, HV PSU based on the TI UCC3803D that runs on 5V or 12V, a VEML7700 light sensor board, a BS612 PIR sensor board, a BME280 environmental sensor board and a power input board.

The modular design means modules can be interchanged with other future variations on this clock. I've already made a IN-12 version of clock.

The Nixies are driven using the Microchip HV5530 IC, this chip is capable of controlling each digit individually without having to multiplex.

It's designed to run from a 5V USB power supply or from a 12V wall plug.

When powering on the clock for the first time after a code upload, the Arduino will broadcast an AP SSID called NixieClock, the password is nixieclock and the default IP is

Once you connect to this SSID, you can configure the clock by navigating to, and connect to your own WiFi. The web interface additionally allows you to change various settings like brightness, NTP options, motion sensor, light sensor and date/time.

The clock is designed to turn the Nixies off when no one is in the room, this is achieved via the BS612 PIR sensor. A VEML7700 light sensor works along with the on/off schedule to determine if the clock needs to be turned off when it's night/bed time.

Every minute all the digits on the Nixies are cycled through using various patterns, this is to reduce cathode poisoning.

As the HV PSU is adjustable, the main Nixie board has trimmer potentiometers for adjusting the anode current.

The three buttons on the front are to display the date, environmental readings, IP address and setting the date/time manually.

YouTube Video

Original Prototype

I had to devour a box of Mr Kipling cakes quickly so I could build the prototype:

Original Shift Register Transistor Driven Prototype with Multiplexing
Even though there were wires everywhere, it worked perfectly on the breadboard

IN-18 HV5530 Nixie Clock Shield_2022-07-16.pdf

For all the schematics see the EasyEDA Project Page []

Adobe Portable Document Format - 171.81 kB - 07/18/2022 at 14:28


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