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IR Sensor problem due to sun light

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udayp

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Sir
i have made a IR sensor using LM324 and interfaced it with 89s52 when it is inside room the circuit works fine when sunlight falls on sensor it stops working. I feel the rays from sun light having IR disturbing it so can you please help me how to solve this problem. Actually the circuit should work in sunlight only.
Any filter or anything whih solves my problem.

Thank you
 

ckshivaram

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you dont get any filters for that purpose.. but you can cover the IR with a black cap or a small plastic enclosure and leave only the front end open..
 

kspalla

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change the bias settings and or directional lens. a plastic piece in convex concave may be placed in front of sensor to make directional. Hope this works fine.
some time you may find from junkyard.
 

jpanhalt

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There are so many details missing that might be helpful. Adding directionality is fine, but then there can be reflections. A detector does not require directionality from dark masks, etc., if it is properly designed and operates within its expected limitations.

Are you using modulated IR, as is incorporated in many devices, or is it just an IRED and detector? What range do you need? Are you trying to detect an object or send data? If detection, are you using reflection or beam break?

John
 

udayp

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There are so many details missing that might be helpful. Adding directionality is fine, but then there can be reflections. A detector does not require directionality from dark masks, etc., if it is properly designed and operates within its expected limitations.

Are you using modulated IR, as is incorporated in many devices, or is it just an IRED and detector? What range do you need? Are you trying to detect an object or send data? If detection, are you using reflection or beam break?

John


No its not modulated the range is 10cm, used for sending the signal to 89s52.
IRLED and detector,beam break type

---------- Post added at 22:53 ---------- Previous post was at 22:53 ----------

Thank you sir
 

jpanhalt

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I think you will have much better luck in various light conditions if you use the modulated type, even with a range of just 10 cm. They are so plentiful and cheap today that there is hardly a reason not to use them.

If you really want beam break without the modules, put your detector at the rear of a small black tube. You can try a soda straw (about 5 to 6 mm diameter) wrapped with black electrical tape and vary the length to see if you get the selectivity you need. I would start with a piece about 5 cm long and shorten it as needed. For a more permanent solution, a piece of blackened aluminum tubing works well. Remember, just because something looks black or dark doesn't mean it won't pass IR.

John
 

vinodstanur

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U can cover it as ckshivaram posted.
Otherwise u need to use some ASK or such methods. Then u need to design a bandpass filter for particular carrier selected for modulation.
But instead of doing such filters etc, u can use TSOP module for receiving particular carrier frequency of 38KHz or like that. But i don't know it is applicable for your need because it got some limitation like low bit rate, need to modulate data with 38KHz (IF TSOP1738) etc....
If u need is just to send some data from one micro to another via USRT or similar applications, then u can prefer this....
 

BradtheRad

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Is your sensor designed to detect only a change in light intensity (beam break)? Then put a capacitor in series with your signal to eliminate any DC component. Then amplify it immensely.

This may or may not require adjusting bias in the detector.

Other advice here is good too.
 

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