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Topic: Infra red receiver at 1.2khz (Read 637 times) previous topic - next topic

ivanseidel

Hi all!
I need to detect a IR wave at 1.2khz of frequency.
I used analog sensors to detect it, but, it just worked for 40cm of distance.
Then, i tried with a 38khz phototransistor, and it only detected the ir signal once, after some ms the signal became 0 and nothing happend, even turning off the 1.2khz emitter.
How can i sense the 1.2khz frequency with a distance bigger than 2m?
Tanks!
Ivan

johnwasser

The 38 KHz receiver module has a bandpass filter to get rid of signals with a frequency far from 38 kHz, like your 1.2 kHz signal.  You probably need a raw IR phototransistor and your own 1.2 kHz analog filter, rectifier, low-pass filter, and comparator.  You can probably do all that with a few op-amps.
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Grumpy_Mike

Quote
your own 1.2 kHz analog filter, rectifier, low-pass filter, and comparator.

Don't forget the amplifier after the filter but before the rectifier. It is this that gives you and increase in distance.

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