“After the successful completion of the XIV Nixie Clock which was Direct/Static Driven, I was keen to start work on a new clock which was based on the Multiplexing(Dynamic) or MUX principle of operation, known also as Muxing. The new clock would be based on the USSR manufactured IV-27V VFD, 13 element, 7 segment tube. This tube requires a 24V common anode DC supply, which dictates what type of IC chip(s) are needed to support the multiplexing operation. To further understand multiplexing the following Wikipedia articles where of great help:
To understand how VFD displays work and what is involved in driving the display using either Direct or Multiplexed driver the following article was very useful:
The clock would have a simple function of displaying Time, Date, Humidity, Temperature, Pressure and an Alarm feature..
Here is a brief summary of how the IV-27M tube works:
The tube is evacuated (vacuum). In the tube is a substrate (anode) (usually based on phosphorus), which begins to shine when “bombarded” with electrons.The electrons come from a heater (cathode), which are in the form of very thin tungsten wires. Between the substrate (anode) and the heater (cathode) a control grid is mounted which is used to turn on and off the individual elements. The tube used here consists of 13 seven-segment displays.
The tube was manufactured in Russia in 1985 and carries the Russian Quality production mark on the rear of the tube. Both tubes I purchased came from an Ebay supplier “nixiestore” who I would highly recommend.
1. Arduino Mega 2560
2. MAX6921AWI Chip
3. TSSOP28 PCB board, 28 pin connection
4. IV-27M Russian 13 grid, 7 segment tube
5. BME280 sensor
6. 3W speaker
7. 16x2 LCD display with IC2 connection board
8. Green LED with 330 ohm resistor
9. RTC clock with battery backup
10. 12V to 3.5V Step Down DC-DC Adapter
11. 12V to 24V Boost DC-DC Adapter
12. 12V, 1A power Adapter
13. Two pole switch
14. 16 key keypad
15. Hot Glue, wood for box, felt feet, clear gloss varnish.
16. 30 AWG multi-coloured wire, heat shrink, PCB female connections.
17. Dupont connection wires
18. Plastic stand-offs for support of components
19. Arduino Board two pin Power Input plug
20. Small PCB board and two sets of header pins”