A Glowing Potato Peeler Makes A Nernst Lamp

Over the last couple few decades there has been a great shift in electric lighting, first towards more compact and efficient fluorescent lights, and then towards LED bulbs. The old incandescent bulbs, while giving a pleasant light, were not by any means efficient. Digging into the history books the incandescent bulb as we know it was not the only game in town; while suspending a filament in a vacuum stopped it from being oxidized there was another type of light that used a ceramic element at atmospheric pressure. The Nernst lamp required its filament to be heated before it would conduct electricity, and [Drop Table Adventures] has made one using the blade from a ceramic potato peeler.

The right ceramic is not the problem given the ease of finding ceramic kitchen utensils, but two problems make a practical light difficult. The copper connections themselves become too hot and oxidize, and preheating the ceramic with a blowtorch is difficult while also keeping an even heat. Finally, they do manage a self-sustaining lamp, albeit not the brightest one.

If you think the Nernst lamp sounds familiar, maybe it’s because we covered it as part of our retrotechtacular series.

18 thoughts on “A Glowing Potato Peeler Makes A Nernst Lamp

    1. To make it work for this application, it’d have to be yttrium-stabilised zirconium oxide ceramic.

      I’ve done a bit of searching but none of the manufacturers want to say what type of ceramic they are. I’d imagine that the physical properties of zirconium ceramic aren’t needed for this application so it’d probably be a different kind?

      The ceramic in “ceramic” heating elements also doesn’t tend to be used like a Nernst lamp (I think there are exceptions though, but it tends to be ceramic that’s doped to be conductive at room temperature, rather than requiring Nernst style preheating). Typically it’s there to physically protect the heating element wires, and provide a better surface for the heat to radiate from, so even if it was zirconium oxide ceramic it’d still need to be electrically connected. I think in the case of the vape coils, it’s just used to provide a container for the liquid being vaporised?

  1. Incandescent: a bit of glass, tungsten, steel, aluminum and tin. Lasts about 1000 hours.
    CFL: e-waste combined with toxic phosphors and a bit of mercury. Lasts about 1000 hours before filaments start to fail from on/off cycles.
    LED: plastic case filled with hazardous e-waste. Still lasts about 1000 hours because now components are rediculusly overdriven and fail from excess heat.

    So in essence we’ve went from something easy to recycle and non-toxic if dumped to something that cannot be recycled (unless your idea of recycling is a burning pile of trash in Africa).

    1. How do you recycle your incandescent lamp? In the EU/Austria they have to be thrown in the waste bin because the glas can not be used to make bottle-glas and the cement-glue has to be separated from the steel. By that time the little mostly oxidized tungsten is lost….
      You should also think about the energy going into the production of the glas an tungsten…
      Torches with wale-oil seem to be the only way…
      The lifetime of all Lamps depends highly on the manufacturer. Where there are not clear rules regarding the condition of testing it tends to be of marketing value only. The lifetime of incandescent bulbs went down sharply in the last 50 years…(my personal impression of course)

      1. The bottles and jars you do throw into glass recycling aren’t actually re-made into bottles either because they’re not all the same kind of glass, so the end result would be worse. There’s brown bottles, green bottles, clear bottles, borosilicate, soda lime glass, different amounts of this and that… separation by color is somewhat possible, but by chemical composition, not.

        Non-refillable glass bottles mostly end up as crushed aggregate mixed in concrete, as road filling, and spun into fiberglass insulation. They’re not actually recycled.

      2. Actually, the quality and life of incandescent lamps has gone down. I read about the hose drying tower in an old fire station in (I think) Los Angeles. Up to the time the station was torn down, the always on incandescent lamp in the top of drying tower was the original installed 75 years earlier – a good thing, as there was no practical way to replace it. The manufacturer had been out of business for more than 50 years.

    1. Saw that one when it was posted. Although it was the Retrotechtacular article here that I first found out these things existed, that video made me want to give building one a try…

      And for once I’m very glad that PhotonicInduction didn’t “turn it up until it pops”!

  2. The problem is that the ceramic must be hot enough to conduct right up the connection with the leads. This reduces the problem from a metal that doesn’t burn at incandescent temperatures to a metal that doesn’t melt at near-incandescent temperatures, if you can shield the connection point from the atmospheric oxygen. The nice part is that this shield doesn’t need to be optically transparant, so it could be anything sufficiently heat-resistant.

    I’m thinking tungsten wires for the connection, with some kind of ceramic to shield it from the oxygen.

  3. If it’s efficiency and long life you’re after then an inductively coupled fluorescent tube is what you’re after. Due to the nature of their electrodless construction, they effectively last forever under their rated conditions and if the unit is designed properly the rf leakage can be more or less negligible compared with a light fitting of similar output. They are rarely seen these days but the are still in production for some niche applications. They probably don’t seem commercially viable because you don’t need to replace them unless they are physically damaged.

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