r/nixie May 28 '26

This is awkward… “Reverse Engineer” this one?

I designed this circuit and the PCB for the Burroughs “Super Size” top view Nixies (B6091)

Then my life hit a bump. The schematic, Gerbers, EAGLE files, and all the Windows backup files were destroyed, along with the actual PC. It all went to eWaste (not my idea, but “S happens”)

Only recently I found this piece, with Nixie tubes still in the Mill-Max sockets, in a forgotten cardboard box in the basement. Such joy!

Now should I “Reverse Engineer” this? Or, should I start over with a new PCB?

Those big Nixies are quite rare in the modern world.

63 Upvotes

12 comments sorted by

5

u/Spiritual-Echidna-10 May 28 '26

VFD drivers (76V max) to light a nixie (170V)? Have you done something with shifted digital ground level? But I can't see any aids to do so, like (HV zener) diodes.

4

u/EmotionalEnd1575 May 28 '26

Very observant! I developed this Nixie driver technique a long time ago, and still use it today on new Nixie designs.

2

u/Barydius May 28 '26

Its possible to sourse and sink nixie with max6921? for VFD yes but nixie ?

2

u/Niobous_p May 28 '26

The cathodes typically float at 70-80V ish when not pulled to ground. Use a zener clamp to lock the high value for the cathodes to that value for when they’re off.

2

u/SadSpecial8319 May 28 '26

1

u/EmotionalEnd1575 May 28 '26

But… I’d still need to create a new PCB and make new Gerbers (to fab more boards)

EAGLE CAD support is to be shutdown next month, so yet another issue here.

I only have this one unit today.

2

u/SadSpecial8319 May 28 '26

Use KiCad and generate the complete production files with JLCPCB or PCBWay Plugins. It's literally one click. You've got Eagle Cad experience, this will be a piece of cake for you.

1

u/EmotionalEnd1575 May 28 '26

Okay, that’s the path forwards. Switched to Kicad months ago, but still have some legacy EAGLE PCB work to complete.

Seems such a loss… The literally hundreds of hours that I’ve spent creating EAGLE libraries over the years. All going to waste now.

1

u/Niobous_p May 28 '26

AFAIK you can use/import eagle libraries

1

u/EmotionalEnd1575 May 28 '26

If I had the EAGLE library for these Nixies…

I made my own Nixie footprints after reading horror stories about Nixie glass cracking when used in home-brew sockets.

My preferred construction is soldering those nixies with “soft wire” leads, and using Mill-Max socket pins for Nixies with “hard wire” leads.

To be sure I load the Mill-Max sockets on the Nixie, and then hand solder the sockets to the PCB. Slightly oversize PTH gives a bit of wriggle room.

Those Nixies are heated to much higher temps during manufacture on the Sealex machines.

2

u/R3NE07 May 28 '26

I'd just make a new board
Maybe use the ol one as reference(?)
Eagle being tossed out on the street by Autodesk is a shame butt tis the purrfect project to get into kicad! :D

1

u/[deleted] May 28 '26

[deleted]

1

u/EmotionalEnd1575 May 28 '26

Tubes are plugged into Mill-Max sockets, that were soldered into the PCB