The 6-digit VFD Clock design was inspired by the very popular 6-digit Nixie Clock. We opted to use IV-22 VFD tubes for the digits together with DM160/CV6094 tubes for the colon separators. Both types of tubes are still available in relatively large quantities. As the IV-22 VFD tubes have the same dimensions as the IN-12 nixie tubes used in the original clock, we decided to use the same setup and dimensions for the new design. With a similar acrylic enclosure the clock looks very familiar, yet different.

The heart of the clock consists of an ESP-32-DevKitC module from Espressif. Time is synchronized via NTP over a WIFI connection with the internet. The settings of the clock can be altered via USB or via the WIFI network connection.

The VFD tubes are driven in a 2 x 3 multiplex mode using a Microchip HV518P high voltage shift register driver. A simple 7555 based step-up converter generates the 50 V anode voltage, while a Texas Instruments PTH08080W step down module supplies the 1.1 V filament voltage.

Features:

• 9V DC power supply, 3 W maximum power consumption
• 12 or 24 hour time format
• date format dd/mm/yyy, mm/dd/yyyy or yyyy/mm/dd
• temperature display in Celsius or Fahrenheit
• supports DS18B20, DS18S20, DS1822, LM75 and SE95 temperature sensors
• RGB tube backlighting with selectable color options
• different colon separator modes (flashing, AM/PM, ...)
• 1-wire and I2C interface
• sleep mode with adjustable night light option and wake-up via a push button
• fully designed for through hole components and modules
• command server for network configuration
• the clock firmware was written using the Arduino environment