IN-12 nixie clock

Ever since i discovered nixies i wanted to make a clock with them, but all the designs i found were for 4 or more nixies, required a custom power supply and a complicated driving system.

IN-12 nixie clock

As the cheap guy i am, i didn’t want to buy lots of nixies or components to make such complicated circuits. And after ages looking for a simple clock design i came up with this page.

This clock uses a single chip which i’ve already used before, the PIC16F84A. The circuit is also pretty simple since it uses a single nixie, driven by discrete transistors and doesn’t need a powerful HV supply.

In the page only the schematic and code are provided because this guy builds his circuits on veroboard, But i wanted to make a good-looking clock so i decided to design and make a PCB.

The tube i’ve used is an IN-12A, but a B variant can be used as well (or any other nixie tube with the proper circuit modifications). The high voltage supply uses components from a disposable camera, so it also costs almost nothing.

The clock displays the time periodically flashing the digits from tens of hours to minutes.

To set the time you have to push the button when the digit you want to change is being displayed, it will increase each time you push and cycle from 0-9.

If you hold down the button during power on, the clock will rapidly cycle trough the digits. It is useful to kill off some “cathode poisoning” on nixies that have not been used in a while.

Step 1: The main board

The main board contains all the components except the high voltage power supply, so anyone can build a different HV circuit without changing this board.

The .brd and .sch files are available so you can modify the circuit as you please

The PDF file is linked down so you can make your own PCB.

The components needed for this board are:

-The IN-12 tube (4$ on ebay)

-A PIC16F84A

-10x high voltage SMD transistors (I’ve used the MMBTA42)

-13x 0805 resistors

-A 4MHz crystal

-2x 22pF capacitors

-A push button

-2x 2pin female headers + 1x 2pin 90º male header

-Fine soldering skills

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