My Nixie Addiction

PRISM – Direct Drive Clock

One thing that I’m not so clever with is the software that drives clocks. I can cope with updating displays, fetching time from NTP sources, changing LED colours and dimming Nixies.

I understand and use the ‘state machine’ concept to emulate a kind of multi tasking environment and I’ve even dabbled with interrupts but where It all falls over for me is in the publishing of web pages in order to change clock settings – that is knowledge that I just don’t have 🙁

I have built a few kits from and have seen their software develop as well as the range of clocks on offer. 

I was lucky enough to be offered a PCB for a prototype Direct Drive IN-18 based clock which had all the features I liked including web based configuration pages etc so I jumped at the chance. I procured the required components and pushed the whole thing together. Before long I had a clock with all the features I liked.

Both the hardware design and software are ‘Open Source’ so I decided to have a go at making my own version to work with Z566M (and pin compaitible) tubes.

The circuit shares several common ‘building blocks’ with some of my designs including 5V (Buck Converter) and 170V (MC34063A) power supply circuits as well as twin HV5622 HV shift register / drivers.

Before long I had established the layout of a ‘controller’ board which had the power supplies, WeMos and level shifter components in place. I then set about the tube board which has the HV5622 Shift Registers, anode resistors and tube sockets. It also has provision for Colon Towers (LED or Neon) as well as neopixels for those who like the under tube lighting (like me).

PRISM Controller V1.1

PRISM Controller V1.5 with revised power supply layouts

PRISM Controller V1.568 with NCH6300HV module for the HV


Tube board for Z566M and pin compatible tubes

Tube board for IN-12

Tube board for GN-4P and pin compatible tubes

Tube board for Burroughs B5441 and pin compatible tubes

Tube board for QS27-1 and pin compatible tubes

Tube board for IN-18 tubes

Tube board for Z568 and pin compatible tubes including Dalibor Farny R|Z568M and Millclock ZIN70 with Nixilogy colon separators – 396mm x 60mm

Tube board for Millclock ZIN70 with suport for Millclock Colon Seperators –  440mm x 65mm

No sooner said – than done!
IN-4 Tube Board

Tube Boards

It rapidly dawned upon me that I could actually make tube boards for various other tube types by changing the footprints and adjusting the tube positions to suit. Accordingly I have already laid out tube boards for Z566M etc. ZM1020 top view tubes etc, IN-12, QS27-1 and IN-18.

All tubes being driven directly via the HV5622’s.  The HV5622 are designed to run at a 12V logic levels and although many designs work OK at 5V, given that the WeMos works at 3V3, the controller board features a CD40109 level shifter to take the 3V3 signals and turn them into 12V signals.

The two boards are connected uising headers and sockets on a 0.1″ pitch though rather than use the standard ‘Arduino’ style pins and sockets, I am using turned pins and turned pin sockets. The ‘socket’ pins are broken out out their plastic strips and recessed into 60 mil holes in the PCB. This reduces the inter-board gap to around 6mm which reduces the overall height of the clock. There are also  sets of holes that allow the tube boards to be fixed properly to the controller board using M3 hex standoffs. This makes it easy to fix the entire assembly into the chosen housing.

The controller board has develeoped a little and some minor modifications have been made to some of the tube boards but now – we have a clock (well, several in fact). 

Thus far I have tube boards for:  Z566,  General B13-B socket for top view tubes, IN-12, IN-18, QS27-1, NL5441 and R|Z568M – all ticking away – PM me if interested.

The controller for Z568/R|Z568M and ZIN70 tubes features the new NCH6300HV power supply from Omnixie.

I can supply bare boards with download links for the software, bill of materials,  with links to suppliers and construction notes or complete kits of components and PCB’s. PM me if interested.

If you have a tube type that is not catered for and you’d like a board for them, just let me know – I love a challenge (Nixies only, non biquinery). 

Construction Pictures

Here are a few shots of the boards under contstruction as well as a few glamor pics!

A closeup on part of th HV power supply.

More HV detail

WeMos Mini controls everything


Tube underlighting is not everyones cup of tea so there are configurable options which include turning them all off!

Burroughs B5092’s in action

The controller board behind a tube board

More HV Supply detail

The board interconnections are made by removing turned pins from turned pin socket strips which provides an economic and low profile interconnection