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.