“XIV Nixie Clock V1
Project Date: December 2018 March 2019
WARNING: Nixie tubes require 180v to operate, this is a dangerous high voltage and you need to handle the tubes and the supporting circuitry with great caution.
If you would like to use Nixie styled tubes in your project, which are safer to handle and use, then consider the VFD type of tube, similar character style, and style of tube but these tubes only require 27v to operate.
This is my first Nixie styled clock I have constructed. The clock actually consists of two clocks, the first being a 6 x IN-18 tube clock which is mounted on the clocks top and displays both time and date. The second clock, this time based on 6 x IN-12A and 2 x IN-15A nixie tubes displays at the front of the clock and can display, time, date, pressure (with units and trend), temperature (both Centigrade and Fahrenheit) and, humidity (with units and trend). The time and date are separated with two single neon lamp-based separators, while only one of these lamps is displayed, to represent a decimal point, when the pressure, humidity or temperature is displayed. Both these clocks use Direct/Static Drive to power the displays and are based on two Arduino Mega 2560 boards. The fourteen tubes are driven by 12V to 170V DC to DC boost power supplies and 14 x K155 IC chips. The clock also powers two sets of Neon Lamps which switch off while the clock goes through its cathode cleaning cycle which happens at 19, 39 and 55 minutes past each hour. This cathode cleaning cycle consists of all six tubes displaying the digits 0 through 9 in sequence 6 times.
In addition the clock will sound a chime at 15, 30, 45 and 60 minutes. At the 60 minute chime the hour chime is also sounded. The chimes are standard MP3 files using a simple MP3 player controlled by the Arduino mega. In order to save on tube life all tubes are switched off automatically when the light level in the room dims to a predefined level, this is achieved using a LRD resistor located at the back of the clock. To help dissipate any heat build up both Arduino Mega ICs have copper heat fins attached and a 5V fan draws air out of the clock, cool air entering through a hole in the bottom plate.
The user can adjust the time, date, Chimes, and Chimes Volume using one of two 16x2 LCD displays, located at the back of the clock. The BME280 temperature, humidity, and pressure sensor is mounted on the back of the clock so as to not be affected by the clock’s internal temperature.”