Problem with Photo diode.

[nikhildascl]

I am doing a project with Photo diode and IR LED. At normal light conditions, it is working and Photo diode sensing properly. But, when exposed to little more light(sunlight), it is sensing more and Photo diode output is giving the full voltage(Vcc=+5V). How can I solve this problem?

 

[dselec]

What is "more" ?
what is normal
u working with 2 options obstruction or not between led and photo diode all surrounding light must not reach the photo only the obstruction will decide.
what is the led number ? if u working with photo diode why u expose it to sun light ?
sunlight also has some infrared light and all the rest of spectrum in that so your photo will respond to all types of light.

 

[keith1200rs]

Options are to add optical filtering if you haven't got it, but most likely you need to modulate your light source and reduce the gain of your detector - then AC couple and add filtering and more gain as required.

Keith.

 

[nikhildascl]

How to adjust the gain? Is it possible to reduce the voltage using Potentiometer?

 

[keith1200rs]

How to adjust the gain? Is it possible to reduce the voltage using Potentiometer?

It is impossible to say without seeing a circuit! However, reducing a resistor value somewhere is likely to be involved.

Keith.

 

[nikhildascl]

This is the circuit i have...

 

[keith1200rs]

You would have to reduce R2/R3 to reduce the sensitivity to sunlight but you will of course also lose your wanted signal. It is usual to modulate the LEDs and have some filtering. The Vishay TSOP range of detectors will do a lot of the work for you which would be far easier than designing and building your own.

https://www.vishay.com/ir-receiver-modules/

Keith.

 

[HTA]

You might take a look at this application report, using a daylight suppression integrated into the phototansitor: **broken link removed**

Enjoy your design work!

 

[dselec]

This is the circuit i have...

u have not explained yet how are u going physically modulate the photo diode ?!!!
in general show how /where actually the diode and sensor r situated is is most important to understand how ambient light (even temporally flash or strobe if its for disco or music hall).
next u will need to know characteristics of photo diode for regular light ursus infra red light using data sheet ..
i meen what is the transfer rate of sensor for ambient or other light versus infra light ?

---------- Post added at 16:48 ---------- Previous post was at 16:38 ----------