29 Apr '12, 1pm

use an LED as a light sensor O_O

LEDs are commonly used as lights, but then can also be used as photodiodes to detect light. This example circuit uses a single LED to sample the ambient light level and then glow at an appropriate brightness. It is tragically flawed by a slow refresh rate in the dark, but it shows how to sense. // // This example shows one way of using an LED as a light sensor. // You will need to wire up your components as such: // // + digital2 // | // < // > 100 ohm resistor // < // | // | // ----- // / \ LED, maybe a 5mm, clear plastic is good // ----- // | // | // + digital3 // // What we are going to do is apply a positive voltage at digital2 and // a low voltage at digital3. This is backwards for the LED, current will // not flow and light will not come out, but we will charge up the // capacitance of the LED junction and the Arduino pin. // // Then we are going to disconnect the ou...

Full article: http://arduino.cc/playground/Learning/LEDSensor

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