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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  • Astable Multivibrator vs. Charged NP-BX1 Lithium Battery

    Hitching a charged, albeit worn, NP-BX1 lithium battery to the astable multivibrator produces a blinding flash:

    NP-BX1 Holder - SMT pogo pins
    NP-BX1 Holder – SMT pogo pins

    The current pulse shows the wearable LED really takes a beating:

    Astable - NP-BX1 4V - 100mA-div
    Astable – NP-BX1 4V – 100mA-div

    The current trace is at 100 mA/div: the pulse starts at 400 mA, which seems excessive even to me, and tapers down to 200 mA. It’s still an order of magnitude too high at the end of the pulse.

    On the other paw, maybe a 14% duty cycle helps:

    Astable - NP-BX1 4V - base V - 100mA-div
    Astable – NP-BX1 4V – base V – 100mA-div

    The top trace shows the base drive voltage dropping slightly, although I suspect the poor little transistor can’t take the strain.

    The LED really does need a ballast resistor …