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Selection of infrared components and calculation

  1. Aug 26, 2009 #1

    Can any experts give me some advice on the selection and calculation of infrared in control.

    I want to do a simple sensor control by PLC which utilize the infrared.When the receiver detects the infrared from the transmitter, the signal will trigger the PLC for some form of control.

    At this point, photo sensitivity, wavelength, noise is not of my concern.However,I want the range of detection to be about 30-45 degree and at the length of about 1 metre.

    I thought of using phototransistor because i saw some receiver circuits using it. My problem is how do I amplify the signal to 24v so that the PLC can recognize it. Is phototransistor works the same way as the transistor?Is the calculation similar in obtaining the Ic, Ib, and Vce?

    Can the phototransistor works like the transistor and amplify the output voltage Vc to 24V?
    If not should I use another transistor to do that?Or should I use an op-amp to do that?

    Any advice is very much appreciated.

    Thank you.
  2. jcsd
  3. Aug 26, 2009 #2
    Yes, except that there is no Ib as it is controlled by incident light.
  4. Aug 26, 2009 #3


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    Here's a little application note for common collector and common emitter photo transistor circuits: "www.fairchildsemi.com/an/AN/AN-3005.pdf"[/URL]
    Last edited by a moderator: Apr 24, 2017
  5. Aug 26, 2009 #4
    Thanks alot.
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