Introduction: ILC1-1/8L Clock

About: Now retired but have a passion for robot design and construction. Also enjoy programming, my career was largely commercial programming and design work using Cobol, Fortan, and industrial automation and integra…

Project: ILC1-1/8L Clock

Date: Sept 2019 – Oct 2019


This project was undertaken to make use of the ILC1-1/8L VFD tubes, otherwise the project uses standard components and provides the display with time, date, Chimes, pressure, humidity, temperature centigrade, and Fahrenheit. Using the multiplex method to attach each tube in series with the separated 24V supply lines attached to the IC Chip, and the 3.5V heater supply line is attached in series with each tube.


1. Arduino Mega

2. 4X4 Keypad

3. Single Pole Switch

4. BME280 Sensor

5. Light Detecting Resistor

6. 22 ohm resistor (In series with Light Detecting Resistor)

7. MAX6921AWI IC Chip

8. DC Step Up booster 12V – 24V

9. DC Step Down converter 12V – 5V

10. DC Step Down converter 12V – 3.5V

11. 16 X 2 line LCD Screen with I2C communications

12. MP3-TF-16P mini player

13. 4 ohm / 5w Speaker

14. 22 ohm resistor (In series with Speaker)

15. RTC Clock DS3231

16. LED Red Light

17. 330 ohm resistor (In series of LED Red)

18. 1K ohm resistor (In series with TX mini player)

19. 12V 1Amp power adapter

20. MP3-TF-16P mini MP3 player

21. Acrylic Glass

22. Mahogany board


Construction started with the Arduino Mega being attached to a power distribution board and a single SCA/SCL distribution board. The 12V 1A power adapter supplies 12V to a power distribution board which supplies two DC-DC Step down adapters one supplying 5V to the distribution board and the second supplies 1.5V to the ICL tube display array. One of the 12V supplies from the distribution board supplies a single DC-DC Step Up booster adapter which is used to supply the 8 X 24V supply lines which support the ICL tube display.

The Arduino Mega SCA/SCL lines are attached to the 16X2 LCD display, BME280 sensor, DS3231 RTC, and MP3-TF-16P. 5V supply from the 5V distribution board is attached to the 16X2 LCD, RTC Clock, and MP3 player, a single 3.5V line is attached to the BME280 sensor. The SCA/SCL lines are attached to the IC2 communications board attached to the 16X2 LCD screen.

The MP3 player is attached to the 5W / 4-ohm speaker, a further 5V supply is attached to the Line-In of the Arduino Mega and to the MAX6921AWI IC Chip. A further 5V supply is provided to the Light Detecting Resistor and the signal line from the LDR is attached to A15 of the Arduino Mega. Lines 2 to 11 of the Arduino Mega are attached to the 16-digit keypad, Keys A, B, C, D, and “*” have been painted over as they are not required.

The back plate of the clock is holed to allow access for the 16X2 LCD screen, control lines of the 16 keypad, speaker, LDR, and BME280 sensor. The MAX6921AWI IC chip is attached to the underside of the top plate. Apart from the 5V supply and GND lines the IC Chip has three control lines attached to Pins 25,27, and 29.

The central clock unit complete, with front plate with 8 x ILC-1-1/8 VFD tubes and the rear plate with LCD display, 16 key keypad, BME280 sensor and Light Detecting Resistor, is enclosed within a mahogany frame with two solid ends into which a shaped copper support is attached. Each of the four frames has a trench in two sides into which a grayed acrylic glass is placed in the front plate, the bottom and top trenches are filled with black paper and aluminum plate while the back plate is covered with an aluminum plate only as the rear plate has been painted mat black.


The software was developed from the original Steampunk Radio Master program. The “DFRobotDFPlayerMini” driver is used to support the MP3-FP-16P mini player. The Arduino Mega uses control lines 25,27, and 29 to control the MAX6921AWI IC Chip. Via the menu system the display can be blanked by the system checking the value from the Light Detecting Resistor, if set to “yes” the display will blank when the light level matches the limit set in the software otherwise it will continue to display during the hours of darkness. At 15, 30, 45 past each hour and at the head of the hour the system will sound chimes using the MP3-FP-16P mini player.

See attached Arduino file and details of the additional Library files needed to support the code.

Include Files: LiquidCrystal_I2C.h, Wire.h, SoftwareSerial.h, DFRobotDFPlayerMini.h, SparkFunBME280.h, RTClib.h, Keypad.h


This project used many of the previously used components however use of the MP3-FP-16P mini player was new and required some additional testing and development. The size of the ILC1-1/8L tubes makes this a great large format clock which can be viewed across the largest of rooms. Re-use of the MAX6921AWI IC Chip was only complicated by the re-mapping of segment elements and those defined in the software. The six ILC1-1/8L display tubes I used where manufactured in 1992 but new old stock can still be purchased via E-Bay.

There is not much information on the web regarding these tubes however one source is:Kevin Rye a great site and Kevin has often provided me with great help and advise on all things Nixie and the MAX6921 IC Chip.