infrared proximity sensor

How about the wavelength of your emitter - does it match the detector?

How about the frequency of the modulation - does that match the detector?

I'm assuming the emitter is normally off, and only pulses on for the modulation with a near 50% duty cycle.

Luhan

maybe its the way your Tx and Rx it ? if your looking for a simple presents of IR in the Rx LED then you might have problems there since the levels will vary alot.. using mulitple Tx leds also helps to spread the radiation patern around a bit. you should be using a pulsed IR tx output and on the RX end passing it through a bandpass filter to clean up other noise. if you use op-amp with the - input for the RX LED and then have a resistor from that input over to the

• input with a series LC reasonator from the + input to common selected for the carrier frequency your using, you should be able to detect very weak to strong signals with no problem. i did such a project years ago. you can simply use a cap to common if you wish for only the high freq effects to the present but then you may run into problems of other IR devices tripping the signal unless you use a PLL chip like the old LM567 i think it was?