Photodiode

Good job, beautiful ! Perfect to quickly test a circuit, to share, to illustrate a report... Maybe the future standard for DIY guys...

Just a question: i'm trying to simulate a light emitting diode/photodiode couple but it doesn't works, does the light emission/reception is working ?

Thanks !

by jeanpri
March 01, 2012

Thanks! The LED/photodiode symbols do show little arrows corresponding to photons emitted / received. However, their physical placement on the schematic doesn't imply any actual connection between them, so there's no photocurrent running through the photodiode.

You could model that by adding a CCCS (Current-controlled current source) in parallel with the photodiode, with some ratio to capture the transfer between input and output. Take a look at this:

If roughly 1 in 10,000 photons from the LED reaches the photodiode (and ignoring the quantum efficiency of both devices), then we can set the CCCS to have a gain of 10-4. Hope that helps!

by mrobbins
March 01, 2012

Thanks for this useful tips !

I agree, the fact that photo-current works in function of the emplacement would be funny but not very serious...

by jeanpri
March 02, 2012

Pls can any one in the forum help me with the below project cct design.

This project combines two apparently competing communications methodologies: radio communications and optical communications, . The idea is simple in general terms - an radio frequency signal is carried on an optical/infrared signal from one point to another, and then converted back using photodetection into a radio signal again which can then be detected using a radio receiver.
Thanks

by nurafalalu
May 14, 2013

Please do not double post.

See reply here:

https://www.circuitlab.com/forums/optoelectronics/topic/t9z5dn3a/project-design/#comment_5222

Thanks.

by signality
May 16, 2013

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