Nixie clock #2 - multiplexing

Previous post: Nixie clock #1

I had to choose my project for embedded systems classes (containing some kind of display, communication module, some other parts like sensors, etc.) and I proposed to continue with my nixie clock. I will have to add automatic time downloading from the internet. I'm going to use cheap & popular wifi module esp8366:

Today I finished my second PCB for this project, board performing signal multiplexing for tubes. Inputs are HV from the boost converter, digit and tube activation signals. On the output correct tube gets power supply and specified number pin is driven. I put a lot of work into it (done in period of 2-3 weeks in the evenings), fortunately the board works:

Nice views by copper & salts during etching so waiting wasn't too boring :)

Nixie clock #1 - boost converter and my first PCB

Some time ago I bought couple of nixie tubes. Nixie tubes look nice especially in the dark. When I've seen them for the first time I decided to build something on my own (I'm going to build a clock).

First I had to build boost converter because tubes are working with high voltage (170-190V). I used this one which converts input voltage in range 9-12V to needed values. Output can be modified with potentiometer. After I bought all parts and assembled circuit I tested it with tube:

Today I've created my first PCB using thermal transfer of a circuit printed (using laser printer) on the special glossy paper. It was also etched in a Sodium Persulfate solution. Results:

It is not perfect but pretty good considering that it was my first time :) I will put on that board my boost converter.

EDIT:

Board after soldering.

Project files:
https://github.com/eszkadev/nixie-clock/tree/master/boost-converter