Nixie Tube clock

Four-digit Nixie tube clock with automatic time sync to an NTP source using a Raspberry Pi Zero W. Tube display control and multiplexing done with an AVR ATmega328p that communicates with the Raspberry Pi through an SPI serial bus.

Software and schematics on GitHub https://github.com/eyalabraham/nixie-tube-clock

AVR controller

AVR ATmega328p provides necessary timing functions and display multiplexing and brightness PWM. TTL buffering for 3.3v to 5v logic level conversion. A photo resistor (LDR) is used for ambient light sensing and input to dimming.

Raspberry Pi Zero W

Bottom of controller board with Raspberry Pi and 5v regulator.

High Voltage power supply

High voltage power supply built according to https://threeneurons.wordpress.com/nixie-power-supply/

High voltage switching

Nixie tube high voltage switching with transistors for anode switches and a Russian K155ID1 / 74141 equivalent BCD decoder

Tube board

Passive wiring and board for Nixie tubes

Nixie tubes

IN-14 Russian Nixie tubes

Tube in socket

Home made socked for tubes based on ideas from https://threeneurons.wordpress.com/miscellaneous-projects/improvised-tube-sockets/

Complete clock

Video of working clock

Schematics and vector board wiring available as PDFs on Google drive: https://drive.google.com/drive/folders/1nii7H3NDByK19VhZ1S-wq9s5eVfae5u6?usp=sharing

Feature list

Hour and minute display
LED multi function indicator: seconds or blink rate change when errors
Self adjusting time with NTP
Display intensity control and dimming of tubes based LDR light sensor
Watchdog communication protection between Raspberry Pi and AVR controller
Nixie protection; ‘slot machine’ effect
Clock tube display on/off (High Voltage on/off) by hour of the day
High Voltage shut off via logic control
SSH for management
XML configuration file
- Configuration changes applied up on the fly
- Time format as 24 and 12 hour format (no AM PM indicator)
- ‘Slot machine’ effect configuration
- Clock on/off periods such as time of day; e.g. midnight to 7am
- Date display configuration

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