Photodiode, I don't know how it works here.

Thread Starter

Xenon02

Joined Feb 24, 2021
504
Sorry again for my slow progress of understanding.
I'm just thinking that if I have this moment when the current is equal Ub/RL then when I give more light it is still Ub/RL but is it still photoconductor ?

If yes then if I use 100 ohm as I said earlier then will I have this diagram where I have photoconductor and photovoltaic? Is it the same for every resistors ?
 

Thread Starter

Xenon02

Joined Feb 24, 2021
504
Diagram for RL = 100 Ω:
1659141487821.png
Okey.
Can you correct me if you can.
If I give more light to the photodiode I still have Ub/RL even if I give soooo much light.

But even if I have Ub/RL as a const at some light level it will change into photovoltaic ?

Because you said something like that :


When you cross Ub/RL, current through photodiode is maximal.
When you give more light, current still equal Ub/RL. Photodiode is saturated.
But here the more light I give the mode will change but the current won't change ? Will it still be Ub/RL ?
 

Danko

Joined Nov 22, 2017
2,179
If I give more light to the photodiode I still have Ub/RL even if I give soooo much light.
Sorry, it was my mistake and followed misunderstanding.
When you cross Ub/RL, current through photodiode is maximal.
When you give more light, current still equal Ub/RL. Photodiode is saturated.
Instead "photodiode" should be "RL".
All that long time I was thinking about RL current.
So, I am TROLL!
Excuse me.
 

Thread Starter

Xenon02

Joined Feb 24, 2021
504
Sorry, it was my mistake and followed misunderstanding.

Instead "photodiode" should be "RL".
All that long time I was thinking about RL current.
So, I am TROLL!
Excuse me.
Hmmm so the photodiode can produce more current ?
Actualy in my current with voltage source resistor and photodiode in reverse. It is the same current.

So if I give more light the current still will be Ub/RL right ? Because this is maximum.
So why is it that when I give more light the photodiode changes from Photoconductor into photovoltaic ? Even though you said that when I give more light it will be still Ub/RL.
 
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Thread Starter

Xenon02

Joined Feb 24, 2021
504
How is it then ?
More light the current is still the same Ub/RL ? If it's still the same then why does it change from photoconductor into photovoltaic ?

If I give more light I will still have Ub/RL and the mode will change into Photovoltaic or will it be still photoconductor ? Because I'm confused either it is still photoconductor or is it photovoltaic because the current is still Ub/RL. Even If I give more light.
 
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Thread Starter

Xenon02

Joined Feb 24, 2021
504
Sorry, it was my mistake and followed misunderstanding.

Instead "photodiode" should be "RL".
All that long time I was thinking about RL current.
So, I am TROLL!
Excuse me.

Could you please tell me how it works ?


How is it then ?
More light the current is still the same Ub/RL ? If it's still the same then why does it change from photoconductor into photovoltaic ?

If I give more light I will still have Ub/RL and the mode will change into Photovoltaic or will it be still photoconductor ? Because I'm confused either it is still photoconductor or is it photovoltaic because the current is still Ub/RL. Even If I give more light.
Because I'm not sure of this statement.
 

Danko

Joined Nov 22, 2017
2,179
When you cross Ub/RL, current through photodiode is maximal.
When you give more light, current still equal Ub/RL. Photodiode is saturated.
Instead "photodiode" should be "RL".
In cited statement I do not take in account forward voltage of photodiode,
added to battery voltage, so after crossing zero voltage on photodiode,
current through RL will gradually increased on Vforward/RL.

ADDED:
2022.07.31 05-28-37.png
 
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Thread Starter

Xenon02

Joined Feb 24, 2021
504
Irving.

May I ask you 1 question ?
Why did you said that this is not how photodiod works? :


Its not how a photodiode works; there is no external current unless its zero-biassed. Maybe this series of articles will help:
https://www.allaboutcircuits.com/te...odiodes-the-nature-of-light-and-pn-junctions/
From this post :


Okey but I mean the example I gave. I want to know theoretically if I changed the mode from photodetector to photovoltaic ?
I mean here What happens if I cross the Ub/RL. Is it photovoltaic ?

View attachment 272454
View attachment 272456

I just wanted to show that when I give to much light. The current won't be Ub/RL but a bit higher. So if I give more light for current Ub/RL (second drawing) then I won't have photoconductor, I will have then Photovoltaic. I know I gave to much current but I wanted to show a concept not an exact values of current ect.

So can you tell me. If I give to much light then I have photovoltaic from photoconductor. Second drawing is Photoconductor, Third is Photovoltaic. I know the value is to high but this is only to understand the concept that's all. So is it true ?
 
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