[Laser] Re : Sensitivity of small LEDs as photodiodes

[Garnier Yves]

Hello Steve

The ultra-bright AllnGaP LEDs seem the better and some of them can even work in avalanche mode with a high voltage reverse biasing and high value serial resistors as kenching device .
http://een.iust.ac.ir/profs/Sadr/Papers/omd7.4.pdf

I did some test with them but the avalanche point is very critical and instable with something like erratic hysteresis phenomenons.
A project could be to try to bias them with a high voltage HF sweep near the avalanche point synchronously with the signal to detect.
May be a beating signal could be detected with an extra gain ???   

73 

Yves F1AVY
http://f1avyopto.wifeo.com


________________________________
 De : steve kavanagh <skavanagh73 at yahoo.ca>
À : laser at mailman.qth.net 
Envoyé le : Dimanche 18 Décembre 2011 16h53
Objet : [Laser] Sensitivity of small LEDs as photodiodes
 
I have been attempting to make comparisons of several small high-intensity
 625-ish nm LEDs as photodiodes for my receiver project.  All my tests show that Cree C503B-RAS LEDs are better detectors than a couple of generic Ebay types, but the results are all over the map, from slightly better to 10 times the photocurrent, depending on test method.  All of them are nominally 15 degree viewing angle 20 mA types.

Does anyone have any experience with the response of such LEDs as photodiodes, or suggestions for good test methods ?

73,
Steve VE3SMA
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