IR photodiode

[walid]

This is a diode operate on Infrared light emitted from an IR diode, the question is: What happen when IR ray strike this diode? Is it become sort circuit? Are there any differences if we connect it in reverse, that is kathode inplace on anode and vise versa. THANKS

[audioguru]

This article explains photodiodes very well:
http://www.udt.com/Datasheets/Other/PhotodiodeCharacteristics.pdf

[walid]

I read the article that explains photodiodes but it is very long and very difficult to understand. I'm too young to read this high level article.
what i want is to answer my questions mentioned above please
thanks

[audioguru]

Photoconductive mode:
You apply a reverse bias voltage to the photodiode which decreases its capacitance increasing its speed.
Radiation on it causes it to conduct leakage current.

Photovoltaic mode.
The photodiode has no voltage across it and connects directly to the virtural ground input of an inverting opamp.
Radiation on it causes it to generate a current like a solar cell.

In both modes the photocurrent is very small. ;D

[walid]

No No No Audioguru you copy and paste part of that article which i can't
understand.
This article looks like Text books that we learned in university, these text
books talk about things in the other world.
I need simply to tell me like this: "this diode is like any diode have a K & A and
it is measure high resistance in the two directions if we are in absolutely
dark room...."

My question again:
What happen when IR ray strikes this diode? Is it become short
circuit? Are there any differences if we connect it in reverse, that is
kathode inplace of anode and vise versa. THANKS

[audioguru]

i can't understand. ..... these text books talk about things in the other world.

Learn the basics of electronics then you will understand technical talk. There isn't an "other world".

My question again:
What happen when IR ray strikes this diode? Is it become short
circuit? Are there any differences if we connect it in reverse, that is
kathode inplace of anode and vise versa.

Sorry, I already answered your question clearly. ::)

Hee, hee. ;D ;D When I am designing a complicated electronic circuit, my wifey thinks I am "in another world". ;D ;D
I'm just an electronics geek, that's all.

[walid]

Thank you Audioguru

[walid]

I'll read that articale very well but I'll ask you about what is hard to understood