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Russian Nixie Tube Clock


I have been fascinated by the beauty of Nixie Tubes since my first encounter with them as a technician in the 1980s.  I wanted to gain some hands on experience with switch mode power supply design and figured the DC/DC supply design needed to drive these tubes would be a good experience. 

I decided to use an RGB LED under each tube and implement the ability to drive each LED with a different color.  The 4 tube clock design would need 12 PWMs for the LEDs alone and 44 I/Os for the tube segment drive.    I used a PIC16F1509 for each tube / LED position, using the device’s (3) hardware PWMs to drive the LEDs, placing them all on a single I2C bus for easy addressing.  A PIC16F1825 acts as an I2C Master, polling the RTC, Temp sensor and IR receiver, writing the appropriate LED and tube assertions to the tube uCs.

I also added a MCP9808 temperature sensor, Super Capacitor for time backup, Vishay IR receiver and PIR detector.    This eliminated the need for push buttons since the DVR remote can be use to configure the clock and set the time.    The PIR detector allows the tubes to be turned off whenever there is no activity in the room to save power and tube lifetime. 

After locating the tubes on Ebay, I used Eagle to complete the design and fabricated the PCBs through Sunstone’s Valueproto service.  The entire design is surface mount and a combination of hand soldering and a hot air workstation was used for assembly.

The case is routed out of a piece of solid mahogany.

- Shared October 10, 2012