Infrared Receiver Circuit

[wat007]

Hi All,

I am trying to build a remote control receiver that can be used outside the house. Thus, this this will be exposed to sunlight. How does my signal be resistant (mechanically or electronic solution) to infrared emitted by the sunlight. Can i use simple IR emitter and detector diodes?

Please advise. Thanks.

 

[Surendhar M]

Simple IR emitter and receiver will not work when you are using in sunlight. may be you can try with RF.

 

[wat007]

My DVD with IR emitter and sensor will work outside expose to sunlight. It must be possible.

 

[Surendhar M]

The IR receiver detects IR signal transmitted, but it detects IR produced by the ambient conditions as well. You must filter out this IR noise to prevent false detections. A common method is to modulate the LED's IR signal with a convenient frequency.

 

[wat007]

I have that in the transmitter side. How do I separate the ambient/sunlight IR from the modulated one in the receiver side?

 

[Surendhar M]

This may work for you.

 

[wat007]

Hi Surendhar,

I will try this later but may I know what if sunlight is always present and it will "fully" turn on my IR detector diode. Will the full ambient light (from the sun) cover the modulated signal?

 

[Surendhar M]

Of course it will so to avoid that possibly you can cover the detector from direct sunlight and also I read somewhere, some time back that the modulating frequency also matters if the frequency is in the range of 38KHz it won't affect the detector. But I'm not quite sure about it.

 

[wat007]

So is there something blocking the sunlight in most DVD IR receivers? Mostly I can see something color brown? Is it a filter?

 

[Audioguru]

An IR receiver IC has a black coat that blocks visible light but passes IR.

Of course an IR sensor becomes saturated in sunlight then is useless as a receiver.
An example will be playing acid rock music very loud and try to hear someone far away whispering to you. Can you see your TV when its screen is in sunlight?

Maybe you can transmit an IR signal that is much more powerful than sunlight then it will work.

 

[wat007]

Understand that but just curious why some remote control system (transmitter and receiver) can still work outside directly facing sunlight.

- - - Updated - - -

I was just checking the remote control system. No need for a TV on that, right?

 

[Surendhar M]

Your curiosity is understood. Those remote control system was working may be beacuse it has been properly covered from the rays of direct sunlight. The sunlight will affect majorly receiver only and not the transmitter. So if you still not satisfy with this then try to replace the position of transmitter and receiver of the system which you are mentioning and try to work under sunlight. I guess it wont work.

 

[wat007]

No, I exposed the receiver to direct sunlight and still it is working.

 

[Audioguru]

No, I exposed the receiver to direct sunlight and still it is working.

Is the infrared beam focussed into a very bright but very narrow beam?
Over what distance did it work in direct sunlight?
Will it still work in direct sunlight when the tx battery voltage has run down a little?