biasing of npn photo transistor

[Akhil Mohan]

Hi,

For my mini project I have purchased a npn photo transistor (l14g2). Can you tell me how can i give a proper biasing for that.

Previously I was using a photo diode as detector and its output is not pretty good, so i am trying with photo transistor

Thanks in advance

 

[ckshivaram]

see this thread .. keith has already addressed this

https://www.edaboard.com/threads/191568/

this also may be useful

https://www.edaboard.com/threads/187770/

---------- Post added at 15:45 ---------- Previous post was at 15:45 ----------

https://www.fairchildsemi.com/an/AN/AN-3005.pdf

 

[Akhil Mohan]

The mentioned link is not opening, I have gone through the data sheet of photo transistor, but am not clear about the biasing levels.

In my photo diode case, I was getting an output but am not satisfied with that one.

Can you help me to design the biasing and detector circuit for an IR input?

 

[ckshivaram]

i think the last link opens the pdf of fiarchild company....

it says Finally, the phototransistor should be biased (voltage applied to VCC ) with 5 Volts. The maximum bias is 16 V, however the performance of the component doesn’t change with a greater bias except when the phototransistor is used as a switch -- the high level output will equal the higher setting.

 

[Akhil Mohan]

I read from the web the photo transistor base leg can be left as not connected. So I am with that.
I will let you know the results later