A simple model of a transistor/LED/photodiode

  • Thread starter granpa
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Main Question or Discussion Point

any objections to using this simplified model to explain current amplification to beginners?


"A simple model with many of the properties of a transistor, especially a phototransistor, is a forward biased LED (emitter–base junction) and a reverse biased photodiode (base–collector junction) sharing an anode (base) in a single package so that 99% (1-1/βF) of the photons emitted by the LED are absorbed by the photodiode. Each electron-hole recombination in the LED produces one photon and each photon absorbed by the photodiode produces one electron-hole pair therefore each electron injected into the base, and therefore the LED, would result in 100 (βF) electrons at the collector"


http://en.wikipedia.org/wiki/Talk:Bipolar_junction_transistor#A_simple_model_of_the_transistor_consisting_of_an_LED_and_a_photodiode
this explanation was directly below the section starting with:
"An NPN transistor can be considered as two diodes with a shared anode region"

for reference:
http://en.wikipedia.org/wiki/Geometric_series
 
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Answers and Replies

  • #2
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apparently such a device is called a "photon coupled transistor"
 

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