Vacuum Tube LEDs: Octal Tube on a CD

Mounting an octal tube socket in a CD requires nothing more than printing one from the same OpenSCAD code that produced the Noval socket:

Vacuum Tube Lights - octal socket - Slic3r preview

Vacuum Tube Lights – octal socket – Slic3r preview

Then apply a 1-1/8 inch Greenleee punch to a randomly chosen scrap CD, match-drill two screw holes, push the knurled inserts into the socket, and screw everything together:

Octal socket in CD - screw detail

Octal socket in CD – screw detail

I totally forgot about the raised ring around the central hole, so the OpenSCAD source code now moves the screws outward to 47 mm OC for a bit of head clearance. The 6-32 screws don’t look nearly so large next to that big Bakelite base.

The 2.36 mm tube pins fit perfectly into the (square!) socket holes without reaming.

This 6SN7GTB would definitely benefit from a ersatz plate cap with an LED shining down on the mica spacer; fortunately, the getter flash is on the side, not the top. You can see the plate cap atop the adjacent duodecar tube diffracted in the grooves, so a CD “chassis” will add some pizzazz to a rather drab tube:

Octal socket in CD - LED diffraction

Octal socket in CD – LED diffraction

In person, you see distinct RGB spots, not a continuous spectrum.

This tube has a completely broken-off base spigot (the keyed cylinder around the evacuation tip), so (I think) more light gets through the base than from a cut-off spigot end. Perhaps the plate cap will add enough light to turn the base LEDs into an accent.


  1. #1 by madbodger on 2016-03-09 - 08:41

    It wouldn’t be tough at all to add novar and magnoval bases (basically the same, but the novars have 1.2mm pins and magnovals have 1.27mm pins: for real socket contacts, this matters, but for this purpose, I think they’re close enough). Like the 12-pin duodecal compactrons, there are many of these around at low prices. I took a crack at it:
    ["Magnoval", 10, 17.45, 1.27, 9.0, 29.7, (4 + 1)/4 * inch, 46.0, 12.4, 38.2], // also Novar

    • #2 by Ed on 2016-03-09 - 09:29

      I added that to the list; maybe someday I’ll get one: thanks!

      Gotta love the similarity between Noval, Novar, Magnoval, and Magnovar, plus the pin diameter differences: “but a Novar tube in a Magnoval socket will not make good pin contect, and a Magnoval tube in a Novar socket may damage the socket”

      The Wikipedia table says Novars had 1.02 mm pins and Novals were 1.016; I think your 1.2 is a typo from 1.02. Close enough for 3D printing, fer shure!

      • #3 by madbodger on 2016-03-09 - 10:20

        Different references give different values. I also hear Russian tubes have slightly larger diameter pins. I also found that RCA refers to Magnoval bases as “Neonoval”.

  2. #4 by Red County Pete on 2016-03-09 - 21:29

    Before my last move, I kept a Type 80 tube (4 pin full wave rectifier) as desk decor. With getter flash up top, and the solid base, I think it would have to be sidelit. It fell victim to the “too much stuff to move” syndrome. Never did figure out what happened to a few things…

    • #5 by Ed on 2016-03-10 - 08:36

      Either a limpet LED glued to the side or one shining up through the (mutilated) base?

      The “too much stuff” thing here means I’ll definitely miss some of it! [grin]