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Archive for October 25th, 2016

Vacuum Tube LEDs: 5U4GB Vacuum Rectifier with Sidelight

A larger version of the V-block clamp accommodates the 35 mm = 1-3/8 inch octal base of a 5U4GB Full-Wave Vacuum Rectifier tube:

5U4GB - spigot milling

5U4GB – spigot milling

The evacuation tip nearly touched the inside end of the base spigot!

I had to cut the shaft and half the body off the shell drill in order to fit it into the space above the tube base and below the chuck:

5U4GB - base shell drilling

5U4GB – base shell drilling

A slightly larger shell drill would still fit within the pin circle, but the maximum possible hole diameter in the base really isn’t all that much larger:

5U4GB - base opening

5U4GB – base opening

The getter flash covers the entire top of this tube, so I conjured a side light for a rectangular knockoff Neopixel:

Vacuum Tube Lights - side light - solid model

Vacuum Tube Lights – side light – solid model

There’s no orientation that doesn’t require support:

Vacuum Tube Lights - side light support - Slic3r preview

Vacuum Tube Lights – side light support – Slic3r preview

A little prying with a small screwdriver and some pulling with a needlenose pliers extracted those blobs. All the visible surfaces remained undamaged and I cleaned up the curved side with a big rat-tail file.

I wired the Arduino and Neopixels, masked a spot on the side of the tube (to improve both alignment and provide protection from slobbered epoxy), applied epoxy, and taped it in place until it cured:

5U4GB - sidelight epoxy curing

5U4GB – sidelight epoxy curing

The end result looks great:

5U4GB Full-wave vacuum rectifier - side and base illumination

5U4GB Full-wave vacuum rectifier – side and base illumination

 

It currently sends Morse code through the base LED, but it’s much too stately for that.

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