Description

This clock is quite small, its dimensions are around 8x9x6cm. It uses the ESP8266 Wemos module as a brain and two PCF8574A ICs for more pins. The clock can be powered from a 7.5V - 15V power supply due to step-up converter based on MC34063 IC. Nixie tubes are multiplexed by 14 MMBTA42 NPN transistors and 4 MMBTA92 PNP transistors. Tube voltage can be freely adjusted by turning a potentiometer. 150V works fine for my tubes. There are two microswitches in the design. I haven't found any usage for them, but you can edit the code as you wish. You can also wire a buzzer there and add an alarm clock functionality.

Preparing

First of all, It requires ESP8266 board package for arduino IDE (ofc)

http://arduino.esp8266.com/stable/package_esp8266com_index.json

There are also some libraries you'll need:

Adafruit_PCF8574.h
NTPClient.h
ESP8266WiFi.h
WiFiUdp.h

Configuration

Here's an explanation of available config:

tubetime - Time in milliseconds of lamp ignite time (Increase when tube is not glowing, decrease when flickering is visible)
utcOffsetInSeconds - Positive offset in seconds (UTC + 2hrs(7200 seconds))

Please, flash the ESP when not inserted into PCB!

Some tubes might flicker from time to time.

Features

• Two programmable I/O - Allows you to give them any purpose you wish
• Low power operation - It consumes less power than a LED clock.

Changelog

02.09.2022 - First version upload.
03.09.2022 - Optimized code, decreased amount of flickering. Improved code readability.
06.10.2022 - Clock will update its time only at startup and then count it itself.
23.10.2022 - Fixed clock de-synchronizing. It is also accurate to a single second.
11.11.2022 - Redesigned PCB a bit. Also fixed the power supply issue (Now using LM317 as a main 3v3 source). BOM has been added!

Known issues

• Clock might get a little bit late over time. There's no fix atm.(Need to restart it every weekend)

Issues

Feel free to open issues.
I am also available on discord: Pastel137#4809