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

  • Cheap Boost Power Supply Evaluation

    For reasons that will become apparent in a while, I got a pair (*) of boost power supplies from the usual eBay source, allegedly capable of boosting a 10-to-32 VDC input to a 12-to-35 VDC output, up to 10 A and 150 W:

    Boost power supply
    Boost power supply

    After establishing that it would not produce 30 V into a 5.9 Ω load (5.1 A, but 152 W), I got systematic.

    A 100 Ω resistor drew 1/4 A while I set the output to 28 V. Doubling up the resistors showed that it worked OK at half an amp:

    Boost supply - 50 ohm load
    Boost supply – 50 ohm load

    Four 6 Ω resistors in series draw 1.2 A, then (channeling the true spirit of DIY 3D printing) two in series drew 2.3 A:

    Boost supply - 12 ohm load
    Boost supply – 12 ohm load

    That’s 32 W each and, yes, they did get toasty, but, no, I didn’t leave them turned on all that long.

    But a 6 Ω resistance still didn’t work, so the supply can’t provide 4.7 A at 130 W. In case you were wondering, that’s two 6 Ω resistors in series and a pair of those strings in parallel, so each resistor still sees 32 W.

    In terms of driving the actual load, these supplies aren’t going to light it up.

    Ah, well, whaddaya want for five buck from halfway around the planet?

    (*) Davy’s Aphorism: Never buy only one of any surplus item, because you’ll never find another. Get at least two, maybe three if it’s something you might actually use.