Archive for February 10th, 2016
Even vacuum tubes destined to be decorations need sockets:
They’re entirely plastic, of course, but they match the dimensions of “real” tube sockets pretty closely. The bosses around the pins have hard-inch dimensions, so you (well, I) can unleash Genuine Greenlee Radio Chassis Punches on sheet metal.
All the key dimensions come from a table, so you can build whatever sockets you need. These four seem to cover the most common relics of the Hollow State Empire:
T_NAME = 0; // common name T_NUMPINS = 1; // total, with no allowance for keying T_PINBCD = 2; // tube pin circle diameter T_PINOD = 3; // ... diameter T_PINLEN = 4; // ... length (overestimate) T_HOLEOD = 5; // nominal panel hole from various sources T_PUNCHOD = 6; // panel hole optimized for inch-size Greenlee punches T_TUBEOD = 7; // envelope or base diameter T_PIPEOD = 8; // light pipe from LED to tube base T_SCREWOC = 9; // mounting screw holes // Name pins BCD dia length hole punch env pipe screw TubeData = [ ["Mini7", 8, 9.53, 1.016, 7.0, 16.0, 11/16 * inch, 18.0, 5.0, 22.5], ["Octal", 8, 17.45, 2.36, 10.0, 36.2, (8 + 1)/8 * inch, 32.0, 11.5, 39.0], ["Noval", 10, 11.89, 1.1016, 7.0, 22.0, 7/8 * inch, 21.0, 5.0, 28.0], ["Duodecar", 13, 19.10, 1.05, 9.0, 32.0, 1.25 * inch, 38.0, 12.5, 39.0], ];
Given that the tubes lack electrical connections, I omitted the base keying: plug them in for best visual effect.
The hole through the middle passes light from a knockoff Neopixel on a 10 mm OD PCB:
Seen from the bottom, each base traps a pair of 6-32 nuts for chassis mounting and has a Neopixel press-fit in the middle:
Those recesses require support structures:
The Miniature 7-pin socket has the least space for the 10 mm OD Neopixel PCB and shows the thin layer between the bottom of the pin holes and the top of the openings.
You see half of the eight holes in the “7 pin” socket, because it has the eighth hole where a standard socket has a gap between pins 1 and 7.
Somewhat to my surprise, punching the support spiders out with a 6-32 stud (grabbed in the drill press) worked perfectly:
They look like I intended to build tiny decorations:
The cookies held on tenuously, then released with a loud bang! as I gradually increased the pressure. A PETG support structure in a blind recess wouldn’t pop out nearly so well.
The OpenSCAD source code as a GitHub gist: