I hereby certify that I am not simply asking someone else to design a footprint for me.
This is an auto-generated message that is in place on the “footprints” section of the KiCad.info forum. If I remove it and ask for a footprint to be designed anyway, I understand that I will be subject to forum members telling me to go design my own footprint or referring me to a 3rd party footprint site.
I am about to start designing my own Nixie clock based on the IN-14 tube.
I need a footprint for the PCB. Has anyone either draw their own, that would share, or find out exactly dimensions?
There are projects on GitHub and/or Hackaday.io that use that model of tube. A search might find you one done in KiCad from which you can take the footprint. I think the footprint is actually of the tube socket.
There’s a footprint wizard in the footprint editor that can generate a circular array of pads. All the parameters (radius, number of pins, pin 1 offset, direction, etc) can be tweaked. I used it to generate a footprint for the CD71 nixies I had. These have leads rather than pins.
You can see in the 3D depiction of the board for the Modularnixie project that pin 1 is not at the top. That’s because the footprint is designed so that pin 10 is at the top so that the viewing direction is from the top. Otherwise you will need to rotate the footprint on the board, possibly by a non-integral multiple of 90°. The CD71 is viewed side on, as is the IN-14, unlike round top tubes which are viewed top on. The red dot on the glass is also not on pin 1 or 10 but on pin 12.
I also numbered the pins anti-clockwise, as is normal for parts like ICs. In the CD71 datasheet the pins are numbered viewed from the bottom, normal for tube diagrams but the opposite convention to ICs, which makes sense since you are soldering to the socket from underneath the chassis.
Just remember, your IN-14 tubes are mounted in sockets. The spacing and dimensions of the socket pins may not be exactly the same as the tube. Use the socket dimensions, in particular the radius and the pin diameter. If necessary, buy the sockets first and measure them.
Fun factoid: A nixie countdown clock features in the film Oppenheimer and even, irony, shows the reversed 2 used for fhe 5 cathode in these Soviet tubes. But this is an anachonism since nixies were invented in the 50s.
I had a short peek at a datasheet for that. Apparently the pins are on a circle with a radius of 11mm, pin spacing is regular (those 27.7 degrees) and thus not a full circle.
KiCad can display polar coordinates:
But this does not seem to work for pad placement. You can generate a circular array (First place one pad, then right mouse button popup and: Create from Selection / Create Array.
Lines can be set with polar coordinates. So one option is to:
Draw some lines with the right length and angle.
Snap the grid origin to an endpoint of a line (Snapping system is a bit complicated in KiCad).
Place a pad at that location.
Repeat for the other pads.
This little test fitting tutorial I wrote 7 years ago may also be of interest:
I had a little peek at: Footprint Editor / File / Create Footprint / Circular Pad Array and created the screenshot below, But from what I can see, it always assumes the pads are on a full circle. I don’t see a start and end angle as retiredfeline implied.
I created a Nixie Footprint sometime ago for another User (a different Nixie). I also created a 3D (STEP and WRL) for use in the 3D-Viewer.
The model was a dumb-model for graphic’s only - screenshot below.
Regarding the number of Pad around the Circle, you can delete any you don’t want. And, you can Create one-Pad then, do a Circular Array of it at whatever angle is desired (just need to learn about Origins and how they reflect on the Array making…)
If User(s) have Cad Skill (in particular, FreeCAD) you can use my Tube Video as a reference…
