IR Break Beam Sensors not breaking

I am experiencing a weird problem with these IR’s.

I had them on the bench and did all the testing, etc beforehand and tried them at different distances.

I have now placed them on my layout at a distance of 18cm apart and before I wire them permanently, I am testing to make sure all is working fine.

However, the break beam on the sensors will not work unless I virtually touch the receiver (makes no difference if I touch the sender) or I completely cover the receiver.
I can even turn the sender unit away or the receiver away and still the break beam doesn’t send the signal down the white wire.

I am using a 5Volt 1amp switch mode psu (which is what I was using to test on the bench). I am getting the same result on each set of IR sensors.

When I place a cover over the receiver, I am getting the full 5v at the end of the white wire.

Any Ideas ???

Hi Glenn,

Are you able to post a link to the IR sensor and how you have it wired up. Is there a lot of natural light around?

If natural light is the issue, the IR Receiver will be being triggered by the IR content in the light which will be a lot more than the LED can produce. The best way to get around this would probably be to shield the Receiver from the natural light but still allow the light from the led to get to it, a small cover with an opening facing the LED should work. You could also combine this with a brighter IR LED and increase the switching threshold so that the natural light does not trigger it. From my experiance Direct sunlight has a lot more IR light content than any LED so the receiver will need to be shielded from the light in some way.

So is the 5mm IR Led’s a light brighter than the 3mm ???