Tags

Items tagged with [circuit]

Using an LED as a Photodiode
Circuit diagram of a darlington pair amplifying the output of a reverse-biased LED Circuit diagram of a darlington pair amplifying the output of a reverse-biased LED +9V +9V +9V +9V D2 D2 D1 D1 Q1 Q1 R1 R1 Q2 Q2 R1 R1 D2 D2 Q2 Q2 Q1 Q1 D1 D1 Circuit diagram of a darlington pair amplifying the output of a reverse-biased LED An LED is a device which takes in electricity and emits light. Some electronic components work in reverse: a speaker can be used as a microphone and a motor can be used as a generator. It is reasonable to ask then, “can we shine light on an LED to produce electricity?” The answer is a surprising yes! LEDs can be made to work as photovoltaics 1, but the reason you don’t see this in practice is that they are really bad photovoltaics. Still, we are able to use this effect in practice, and this trick could even save the hobbyist from having to buy more specialized components.
Tags
electronics circuit led transistor physics