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by segfaultbuserr
2392 days ago
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I don't know why it became such a piece of breaking news. When a current flows through a p&n junction, photons are emitted (and an LED is just a diode that happens to emit photons at the wavelengths of visible light). And it works in both ways, if you hit a p&n junction with photons, you produce a current, not only LEDs - any diode will do that, they're all potential photodiodes, it's just that some are more sensitive than others. You can cause a lot of chips to reset if you shine a bright beam of light to its exposed die, a common way to test chips. It's also one reason (in addition to cost) that most diodes are sealed in plastic package, not glass package. Fun experiment: buy some 1N4148 small-signal diodes in glass package, connect it to a Darlington-pair transistor amplifier, and shoot the flashlight, you'll see some funny thing on the oscilloscope. |
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Putting a light-sensitive chip (I think it was a wafer-scale package with no casing) on a board that's intended for use outside of an enclosure was a really big oversight.