Nixie Tube Clock

Project Specs:

  • Months of work: Feb 2009
  • Approximate Build Time: 2 Days
  • Max Voltage: 190V
  • Max Stored Energy: 8J


Since I became interested in vacuum tubes I decided to build a realistic nixie tube clock using only component types (these exact parts weren’t necessarily available, but there is no microcontroller, etc) available in the 70’s. I designed a schematic using 4017 counting chips configured in /60, /60, and /24 dividers pulsed from a timing device. The outputs then regulate the cathodes of the tubes through MPS-A42 transistors. Nixie tubes operate with a common anode and a cathode dedicated to each element. When a sufficiently high voltage (190V in this case) is applied across the cathode element to the anode, a plasma is formed around the element (shaped in a numerical character), the voltage then drops to a sustaining voltage, and the letter continues to glow at a low holding voltage. This operates electrically just like a neon lamp.

(schematics coming soon, if I ever feel like it… it’s the obvious implementation using 4017 counters and a lot of tedious soldering)

Logic circuit and power supply

Transistor drivers

Operating clock


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: