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Archive for February 1st, 2018

Monthly Science: Wearable LED vs. Dead CR2032 Lithium Cell

Eight months later, the dead CR2032 cell driving the “ruby” wearable LED has dropped to 2.15 V:

Wearable LED - on window

Wearable LED – on window

It’s not a true red LED with a 1.5-ish V forward drop, but a white / blue LED with red phosphor or a red filter, with a forward drop well over 3 V.

Against the sunlit backdrop from our kitchen window, the LED looks dark:

Wearable LED - daylight

Wearable LED – daylight

Seen in a dim room, it’s still glowing:

Wearable LED - dim light

Wearable LED – dim light

The current is now far below the 1 mA/div of my Tek A6302 Hall effect probe, so I have no way to measure the few microamps lighting the junction.

The coarse grid outside the window is a swatch of deer netting we put up during feeder season to keep the birds from killing themselves on the glass.

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