Search Results for: vacuum tube

Vacuum Tube Lights: Duodecar Rebuild

You’ll recall the LED atop the 21HB5A tube failed, shortly after replacing the bottom LED and rewiring the ersatz plate lead, which led me to rebuild the whole thing with SK6812 RGBW LEDs. So I printed all the plastic parts again, because the duodecar tube socket’s pin circle can fit into a hard drive platter’s unmodified 25 mm hole, then drilled another platter to suit:

Duodecar disk drilling

Duodecar disk drilling

The hole under the drill fits the 3.5 mm stereo socket for the ersatz plate lead, so it’s bigger than before.

I’ve switched from Arduino Pro Minis with a separate USB converter to Arduino Nanos with an on-board CH340 USB chip, because the fake FTDI chips on the converters are a continuing aggravation:

21HB5A base - interior

21HB5A base – interior

Adding those wire slots to the sockets definitely helps tidy things up; the wires no longer need a crude cable tie anchoring them to the socket mounting screws.

I wanted to drive the LEDs from the A7 pin, rather than the A3 pin I’d been using on the Pro Minis, to keep the wires closer together, but it turns out that A6 and A7 can’t become digital output pins. So I used A5, although I may come to regret the backward incompatibility.

In any event, the 21HB5A tube looks spiffy with its new LEDs in full effect:

21HB5A with RBGBW LEDs - cyan violet phase

21HB5A with RBGBW LEDs – cyan violet phase

I dialed the white LED PWM down to 32, making the colors somewhat pastel, rather than washed-out.

The Arduino source code as a GitHub Gist:


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Vacuum Tube Lights: Plate Wire Plug

After replacing the WS2812 LED in the 21HB5A socket, I drilled out the hole in the disk platter for a 3.5 mm stereo jack, wired a nice knurled metal plug onto the plate lead, and it’s all good:

21HB5A - Audio plug cable

21HB5A – Audio plug cable

The plug had a rather large cable entry that cried out for a touch of brass:

Audio plug - brass trim turning

Audio plug – brass trim turning

Fancy plugs have a helical spring strain relief insert about the size & shape of that brass snout; might have to buy me some fancy plugs.

This time, I got the alignment right by clamping everything in the lathe while the epoxy cured:

Audio plug - brass trim gluing

Audio plug – brass trim gluing

I flipped the drill end-for-end, which was surely unnecessary.

It’s now sitting on the kitchen table, providing a bit of light during supper while I wait for a WS2812 controller failure. Again.

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Vacuum Tube Lights: Poughkeepsie Day School Mini Maker Faire 2016

Should you be around Poughkeepsie today, drop in on the Poughkeepsie Day School’s Mini Maker Faire, where I’ll be showing off some glowy LED goodness:

21HB5A on platter - orange green

21HB5A on platter – orange green

The 5U4GB side lighted dual rectifier looks pretty good after I increased the phase between the two LEDs:

5U4GB Full-wave vacuum rectifier - cyan red phase

5U4GB Full-wave vacuum rectifier – cyan red phase

A gaggle of glowing vacuum tubes makes for a rather static display, though, so I conjured a color mixer so folks could play with the colors:

Color mixer - overview

Color mixer – overview

Three analog potentiometers set the intensity of the pure RGB colors on the 8 mm Genuine Adafruit Neopixels. A closer look at the circuitry shows it’s assembled following a freehand “the bigger the blob, the better the job” soldering technique:

Color mixer - controls

Color mixer – controls

The blended RGB color from a fourth Neopixel backlights the bulb to project a shadow of the filament on the front surface:

Color mixer - bulb detail

Color mixer – bulb detail

It’s worth noting that the three Genuine Adafruit 8 mm Neopixels have a nonstandard RGB color layout, while the knockoff 5050 SMD Neopixel on the bulb has the usual GRB layout. You can’t mix-n-match layouts in a single Neopixel string, so a few lines of hackage rearrange the R and G values to make the mixed colors come out right.

An IR proximity sensor lets you invert the colors with the wave of a fingertip to send Morse code in response to (some of) the vacuum tubes on display nearby. The sensor glows brightly in pure IR, with all the other LEDs going dark:

Color mixer - controls - IR image

Color mixer – controls – IR image

The switch sits in a little printed bezel to make it big enough to see. The slight purple glow in the visible-light picture comes from the camera’s IR sensitivity; you can’t see anything with your (well, my) unaided eyes.

The “chassis” emerged from the wood pile: a slab of laminate flooring and two strips of countertop, with a slab of bronze-tint acrylic from a Genuine IBM PC Printer Stand that had fallen on hard times quite a while ago. Bandsaw to size, belt-sand to smooth; nothing particularly precise, although I did use the Sherline for coordinate drilling:

Color mixer panel - drill setup

Color mixer panel – drill setup

That’s laying it all out by hand to get a feel for what it’ll look like and drilling the holes at actual coordinates to make everything line up neatly.

Hot melt glue and epoxy hold everything together, with foam tape securing the two PCBs. Those cap screws go into 10-32 brass inserts hammered into the laminate flooring strip.

There’s no schematic. Connect the pots to A0 through A2, wire the Neopixels in series from D8 with the bulb LED last in the string, wire the prox sensor to D9, and away you go.

It’s fun to play with colors!

The Arduino source code as a GitHub Gist:


Vacuum Tube LEDs: Mogul Socket With Platters

Adding two hard drive platters draws attention away from the printed puck holding the microcontroller:

500 W Incandescent - Mogul socket with platters

500 W Incandescent – Mogul socket with platters

Granted, it looks odd. I think it’s a step in the right direction, if there is any right direction at all.

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Vacuum Tube LEDs: Mogul Base for 500 W Incandescent Bulb

This obviously wasn’t ready for prime time, but it demonstrated feasibility with a socket on a base assembled for something else:

500 W Incandescent - backlit light

500 W Incandescent – backlit light

I recently salvaged a heavy aluminum lid that looked like a perfect complement for that bulb:

Mogul base - bulb - blue phase

Mogul base – bulb – blue phase

The light comes from a rectangular knockoff Neopixel in a sidelight mount:

Mogul base - sidelight curing

Mogul base – sidelight curing

That’s epoxied to the rear of the bulb, below the equator, where it casts the best-looking shadow of the filament and support structures on the inside of the bulb. Actually, it’s taped in place for a week’s worth of burn-in to see if it survives.

The Arduino Nano fits inside a small base below the ceramic Mogul socket:

Mogul base - Arduino Nano holder

Mogul base – Arduino Nano holder

The braid exits through a hexagonal trench recessed into the top surface, with a dollop of epoxy holding it in place:

Vacuum Tube Lights - Mogul Base - top - solid model

Vacuum Tube Lights – Mogul Base – top – solid model

The underside has holes for three 10-32 brass inserts:

Vacuum Tube Lights - Mogul Base - bottom - solid model

Vacuum Tube Lights – Mogul Base – bottom – solid model

The center insert is the only thing holding the entire assembly to that aluminum base; I’m not convinced that’s enough, but it’ll suffice for now.

The “computer” certainly gets lost under the ceramic:

Mogul base - ceramic socket connector

Mogul base – ceramic socket connector

The base is slightly smaller than the ceramic to match the flat part of the lower surface; if it came all the way to the OD, you’d see an unsightly notch.

The two screw heads buried down in the recesses thread into the outer brass inserts in the printed base. The ceramic Mogul socket mounts atop that connection block, with another pair of screws making both electrical and mechanical connections to the metal plates-with-screws that used to terminate the incoming power wires.

It’s running the same Morse code firmware as before, with the Morse output turned off, because who needs a giant blinking bulb?

The OpenSCAD source code of the base as a GitHub Gist:

The original doodles with some dimensions:

Mogul base - dimension doodles

Mogul base – dimension doodles

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Vacuum Tube LEDs: 6H6GT Dual Diode

Having accumulated a set of octal tube base clamps, it’s now a matter of selecting the proper clamp for each tube:

Octal tube base V-block clamps

Octal tube base V-block clamps

The process of shell-drilling the tube base, drilling the hard drive platter, printing a tube socket and case, wiring up the Arduino and base LED, then assembling the whole thing requires a bit of manual labor, assisted by some moderately exotic shop machinery.

The getter flash atop this small 6H6GT dual diode tube rules out a cap and there’s not enough space for a side light:

6H6GT - on platter

6H6GT – on platter

Fortunately, the base LED completely lights the internal glass:

6H6GT - purple phase

6H6GT – purple phase

The slowly changing color would make a fine night light:

6H6GT - cyan phase

6H6GT – cyan phase

It must be Art!

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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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