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I am trying to understand 2 sensors that I have here. One says that is "infrared sensor of 38kHz" and the other is "infrared optical reflexive sensor -> http://www.robosoftsystems.co.in/wikidocs/index.php?title=TCRT_5000_Reflective_Optical_Sensor"

I thought that infrared sensor would tell me if an infrared light is passing on it. Infrared light has a wavelenght, right? Can infrared light be emited in different frequencies? Or the frequency of infrared light is the same to all infrared lights?

Samul
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The 38kHz sensor (such as the Vishay series e.g TSOP1838) are designed for use with IR remotes and IR barrier type applications. They are designed to work with IR emitters that oscillate the IR at 38Khz and additionally modulate that frequency with lower frequency pulses. The sensor (receiver) is designed to have high gain at 38Khz and demodulates the signal. The demodulated output signal pulses can be directly decoded by a microprocessor. The main benefit is reliable functioning even in disturbed ambient light thus protecting against uncontrolled output pulses.

Bra1n
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  • thank you so much! But the infrared optical reflxive sensor? Does it also read 38k or any infrared light with any frequency? – Samul Nov 23 '14 at 14:25
  • The TCRT5000 will detect just regular IR light. The output is also analog, so between 0v and 5v depending on how much IR light is reflected. These light sensors will however also pickup sunlight etc. – Gerben Nov 23 '14 at 19:51
  • You are amazing, you helped a lot :) – Samul Nov 24 '14 at 02:02
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38Khz is not the frequency of the IR light but the frequency it is pulsed on and off at, the receiver is designed to accept that frequency and reject others so as to avoid interference from sunlight etc. I see you have asked the question again in a slightly different way and received a similar answer. Infrared led and sensor: how it work

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Bra1n
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