Handmade vacuum tubes

Prywatna Wytwórnia Lamp is Aleksander Zawada's one-man vacuum tube factory, now housed in Warsaw's Institute of Vacuum Technology (Zawada's original vacuum tube factory was in his apartment). Sébastien Bourdeauducq met Zawada and did a great writeup on his handcrafted valves -- and no, it's nothing like Portlandia's artisinal lightbulbs.

He starts the triode by assembling the grid. To do this, he takes a piece of nickel wire, and soldered a small spiral of molybdenum wire on it – one turn and one solder at a time. He uses molybdenum because of its low emission of free electrons when heated (which causes unwanted grid current in tubes) and its high melting point. Soldering is done with a spot welding machine, which passes high current through the parts to be soldered (nickel and molybdenum wires). The current is so high that the metals heat and melt locally and form a small solder spot. How does one obtain such a high current? Aleksander simply took the transformer of a microwave oven, removed the high voltage secondary, and wound instead a few turns of a thick aluminum bar whose ends are connected to the copper electrodes of the welding machine. The solder current can be controlled by a triac-based dimmer connected in series with the transformer’s primary...

As a cheap source of bulbs, Aleksander uses glass enclosures he easily obtained from light bulb factories – they had plenty of surplus stock when incandescent lights were removed from sales in Europe.

Now, let’s assemble the electrodes and the bulb together. He does that by melting the bulb into the base, by rotating it and heating the bottom with a propane torch. Of course, the spinner is also made of junk materials – this time, a turntable that was originally intended to play vinyls.

(via Make)



  1. Properly mastered vacuum technology gives amazing possibilities to a garage lab. For example high-speed high-voltage high-current switches – thyratrons powerful enough to switch megawatt radar pulses, or even krytrons and sprytrons, switches fast enough and with consistent enough performance for triggering the EBWs of a nuclear bomb.

    Then there are the magnetrons, klystrons, traveling wave tubes, crossatrons, and lots and lots of other -trons.

    And lasers, from a helium-neon through CO2 and excimers to the state-of-the-art free electron lasers. (Is there any homebuilt FEL out there?)

    And particle accelerators. And thin layer deposition. And… and… and…!

    And don’t forget high-power triodes, or even a humble diode, as very high voltage diodes capable of considerable current are not so easy to obtain in the world of solid state electronics.

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