Re: Anyone have experience with infrared LEDs?


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Posted by RandyT on 17, 2001 at 3:50 PM:

In Reply to: Anyone have experience with infrared LEDs? posted by Dan on 17, 2001 at 3:16 PM:

: Hi, I've built a few sensors using high-output infrared LEDs and IR phototransistors to simulate a certain arcade game's controls, but their range of detection is fairly small (maybe about 3-4 inches). Does anyone know of any way to extend the range of the IR LED?

: Here's the current layout of one of my sensors:
:


: | |
: | |
: |____|
: | |
: U U
: IR LED-------^ ^--------IR Phototransistor
:

: Basic info: When some object passes under the sensor's range, the IR signal reflects back and triggers the phototransistor.

Correct me if I'm wrong, but isn't your range in this configuration going to be dependant upon:

The output power of the transmitter

The width of the "cone" of energy produced by the transmitter (ie. 10 degrees, 20 degrees)

Angle of the transmitter in relation to the reciever

Geometrical shape of the reflecting object

The surface material of the reflecting object

The sensitivity of the receiver components themselves?

If the receiver is tied to a microcontroller, you might have to bump up the voltage on the output side of the receiver to something just under what will cause the circuit to go to an "on" state. This would have the net effect of increasing the sensitivity of the reciever, but would be hard to prevent a false signal from ambient light sources.

I'm not an electronics engineer, but if you haven't already considered these things, it may be of some help.


For what it's worth,
RandyT



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