The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • Lamp Socket Adapter: Weld Failure

    The basement came with several LED bulbs screwed into old-school ceramic sockets with pull-chain switches. This adapter had an LED bulb in its socket and another LED fixture plugged into an outlet:

    Lamp socket adapter - failed weld
    Lamp socket adapter – failed weld

    The fixture began flickering some days ago, which I attributed to a problem with its power supply. When both the bulb and the fixture went dark, I had enough of a clue to locate the real cause.

    The scorched plastic near the discolored weld nugget on the threaded shell suggests something ran overly hot in there for a while.

    Peeling the aluminum shell off reveals the problem:

    Lamp socket adapter - detail
    Lamp socket adapter – detail

    Looks to me like the weld started out weak and gradually fell apart as the socket heated / cooled in use, with increasing resistance producing more heat every time.

    The LED lamp + fixture added up to 100 W, so about 1 A is all it takes.