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Last week I did a blog where I looked at the response of an LED to light: Experimenting With Using an LED as a Light Sensor . I thought it might be interesting to extend that a little bit further.   As before, the input is a reverse-biased LED acting as a photodetector. Again, I'm going to use an op amp as a transresistance amplifier (this time a Microchip device that can operate on 5V) but, for a bit of added interest, instead of generating an output voltage that's linear with diode cur ...
Does an LED work as a light sensor? Short answer is yes. That's fairly well known, but I've never tried it myself, so here goes.   I'm going to use a couple of old high-brightness red LEDs. I don't know much about them other than that they are definitely high in brightness, have a narrow viewing angle, and the package is 'crystal clear'.   My light source is an Arduino flashing one of the LEDs five hundred times a second [if jancumps can do a 'blinky', so can I!]. I've got a 330R res ...