i am looking for a Infra-Red sensor that can demodulate 36kHz (or w/e) to a nice logic signal.
More importantly, it has to be able to support a continuous 36kHz IR signal.
I recently made a simple photo interrupter project, using leds and photodetectors.
Continuous beam + sensor, if break, something happens.
Now i want to upgrade the beam into a modulated signal so it works better in ambient light.
Im currently using a TSOP1838.
The problem is most IR remote control receivers do not support continuous beams.
It blocks out continuous modulated IR signals, thinking its noise from other devices.
So my question is, does anyone know any IR demodulator that can support a continuous signal?
(im trying to avoid pulsing the modulated signal to fool the sensor.
i think that it would be unreliable and hard to get the timing right.)
and would a SHARP GP1UX31QS do the trick?
i dont really understand the
"Total duty ratio Dt (Emitting time ***/ Transmitting time for 1 block T) : 40% or less."
i think that it would be unreliable and hard to get the timing right.
No it would not.
The problem is that the demodulation amplifier uses those gaps to adjust the biasing on the amplifier. It is not as reliable if you don't pulse it.
im want to send a continuous 'HIGH' signal.
when the beam gets blocked, the sensor will detect a LOW,
this is how i detect if there is a object in the way.
in my old project i used LEDs and an OPT101 sensor.
now i would like to convert it to support modulated IR.
so the source is just a continuous modulated IR signal.
and the receiver is suppose to be a demodulator.
but if found out that IR receivers dont support continuous beams.
Grumpy_Mike:
i see. i thought it was just to filter out modulated ambient light.
my concern is, if my gap is too long,
wouldnt it make the receive think im trying to send a 10101010?
if my gap is too long,
wouldnt it make the receive think im trying to send a 10101010?
Yes if the gap is too long it would, so the trick is to make the gap shorter, that way you will receive a continuous one until the beam is blocked.
However if you want to make one yourself search for a tuned amplifier, this is a circuit I got from google images but the web site keeps getting hijacked when I try and look at it. This will not be as good as the IC however and you will need to change C1 and L1 in the amplifiers feedback circuit so that it resonates at 38KHz (one over two pi root L C -> gives you the resonant frequency (it rhymes if you say it right ) )
You will also need to condition the output so that you can feed it into the arduino, the negative voltage and voltage above +5V will kill the arduino's input.