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.

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  • Halogen Desk Lamp Conversion: Preliminaries

    A discarded 20 W halogen desk lamp arrived in the Basement Laboratory for rebuilding:

    Halogen Desk Lamp - head layout
    Halogen Desk Lamp – head layout

    An incandescent bulb doesn’t care about AC or DC, so a simple transformer also serves as a counterweight in the base:

    Halogen Desk Lamp - 12 V 20 W transformer
    Halogen Desk Lamp – 12 V 20 W transformer

    I might replace it with some steel sheets, although I have no immediate need for a bare transformer.

    A case adds 19¢ to each 10 W 300 mA LED driver:

    Halogen Desk Lamp - 10 W LED driver innards
    Halogen Desk Lamp – 10 W LED driver innards

    Nice strain relief on those line-voltage wires, eh?

    A simple test setup with three 3 W COB LED panels:

    Halogen Desk Lamp - 3x3W COB LED test
    Halogen Desk Lamp – 3x3W COB LED test

    I clamped them to the aluminum sheet for heatsinking before I lit ’em up. The circles traced directly from the lamp’s hardware give some idea of the eventual layout.

    I have more-intense LEDs, but spreading the light over a larger area should work better for the intended purpose. These are pleasant warm-white LEDs, too.

    The fourth LED raised the forward voltage beyond the supply’s 42 V maximum, causing the supply to blink on and off.

    Much to my surprise, the driver has plenty of 60 Hz ripple:

    COB LED 3x3W - 10 W driver - 100 mA-div 10 V-div
    COB LED 3x3W – 10 W driver – 100 mA-div 10 V-div

    The top trace averages 280 mA and the bottom trace 32 V, so the LEDs run at 9 W = 3 W apiece, as they should.

    Now, for some metalworking …