hello,i need your help,i have to design a fifty meters link between a tx and rx infrared,but now i am confusing between the optical and electronical.for the use of an amplifier or just the light.
i have some tx and rx circuit whicth have ir led for transmiter,and a ir phototransistor at the receiver,my big problem is ,how to make it reach fifty meter?
To make it reach 50m (if you can?) you're probably going to need to use decent optics at each end, and accurately align them - bearing in mind that IR does'nt focus at the same point as visible light.
At this distance, it is mostly about optics (lenses, reflectors), and less about the electronics. You will be hard pressed to do much better than the IR Receivers used for TV remote control. Those receivers use 38 to 45 Khz modulation and ac-coupled gain stages to provide immunity to ambient illumination and man-made lighting. Not infrared, but you should be able to learn something here.
The Aerostar hot air balloon "Aegis" temperature sensor works up to about 90 feet. It employs four IR LED's in the top of the balloon that point to a 'telescope' receiver down in the basket. A filter in the receiver passes only IR light. The receiver has a broad angle of reception because the transmitter will move around in the wind.
I was telling someone once about how I had to make a ground strap to the treadmill hand rails because running on it barefoot gives you WICKED shocks (it's a pain in the ass to always make contact with the handrail and if you lose contact for half a second, you'll get a wicked shock). ANd she said I should be careful because I might become electronified.
The treadmill generates lots of static electricity in winter when the air has low humidity and the rubber sole shoes on the rubber rotating surface plus maybe the motion inside synthetic underwear.
Heck, things happen to me when I am on a treadmill or even if I am standing still when a pretty girl walks past.