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

  • Astable Multivibrator: Amber LED

    Adding an amber LED to the collection:

    Astable AA - Amber - overview
    Astable AA – Amber – overview

    Because a yellow / amber LED runs at a lower voltage than blue and green LEDs, it sits atop an astable multivibrator, rather than a discrete LM3909. The battery holder has a pair of carbon-zinc “Extra-Heavy Duty” AAA cells, so corrosion and leakage pose a foreseeable hazard.

    The voltage across the 100 Ω LED ballast indicates a 9 mA peak LED current, which is somewhat dim in ordinary room light:

    Astable AA - Amber - LED current 100 ohm
    Astable AA – Amber – LED current 100 ohm

    The corresponding LED voltage says the LED runs at 2.1 V for that much current:

    Astable AA - Amber - LED V
    Astable AA – Amber – LED V

    Something around 39 Ω should make it more visible.