Photo transistor circuit design

[Murugesh_89]

Hi,
I am working with a photo transistor with the wavelength ranges from 450 to 1080 nm. The current Ica is given as 2.5 to 7.5 mA.
How this current and wavelength are related?
To operate at a given wavelength what value of resistor should i need to place at the collector of photo transistor?

In the graph in the data sheet, it is given that at the 850 nm wavelength it has maximum spectral sensitivity. Since this comes under IR range, should i need to give a pulse with some carrier frequency as we do for normal IR receiver?


Thanks,
Murugesh

 

[wp100]

Hi,

Not aware that you can tune that photo transistor to a particular wavelength.

Its saying that the photo part of the transistor will react to any light in that wavelength range but is most reactive at 850nm.

A beam of strong light at say 500nm will produce a similar collector current to a weak beam of light at 850nm, so how can you determine the wavelength ?

 

[Murugesh_89]

So for a weak beam at 850nm will produce 2.5 mA and a strong beam at 850nm will produce 7.5 mA. Is it?

 

[wp100]

So for a weak beam at 850nm will produce 2.5 mA and a strong beam at 850nm will produce 7.5 mA. Is it?

Hi,

In general terms yes.

Think these two links will help explain things in detail, the second link looks very good for a lot more electronics info.

https://www.daenotes.com/electronics/industrial-electronics/photo-transistor#axzz2KnRmDu00

https://www.radio-electronics.com/info/data/semicond/phototransistor/photo_transistor.php

 

[keith1200rs]

You need to show the datasheet to make sense of the information otherwise we would just be guessing.

Keith

 

[Murugesh_89]

This sensor with the transmitter emitting in near infrared region and photo transistor as the receiver is called as Photo electric sensor or Optical sensor?
What is the major difference between these two?


Thanks,
Murugesh