Help with onto interrupter circuit

Discussion in 'The Projects Forum' started by widpyro, Nov 28, 2014.

  1. widpyro

    Thread Starter New Member

    Nov 28, 2014
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    I am trying to close a relay using an opto interrupter. I have it working to the point where I have an LED becoming unlit when the opto interrupters' beam is broken. I have tried many circuits for amplifying the signal with no luck. Can someone please post a simple circuit for activating a relay? Have 3409 and 2N2222 transistors and 555 iC.
    Thanks,
    Jim
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    What slot Opto are you using? and what is the current rating of the relay? What supply voltage are you using for opto and relay?
    Using a typical slot opto it should be a trivial matter to either use the emitter or collector side of the opto output or amplify it with the 2n2222 or use a 2n7000.
    Max.
     
  3. widpyro

    Thread Starter New Member

    Nov 28, 2014
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    I am using 5v but could go higher if it helps. I have relays rated at 6 volt coil and also some rated at 4.5 volts.
    Yes, it should be trivial, and I've tried multiple circuits that I got off the web, and also feeding the detector side higher voltages. The opto interrupter is part # QTC 9536, but I would be happy using individual components. Any help would be much appreciated. A schematic would be ideal with parts values, etc.
    Thank you!!
    Jim
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Couldn't see anything on the QTC9536? Do you have a link to the data sheet?
    The diode side you select a resistor based on the spec sheet current and your applied voltage.
    Max.
     
  5. widpyro

    Thread Starter New Member

    Nov 28, 2014
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    The marking on the opto interrupter is Qtc9536 H21A2

    I have selected a good resistor to lower the voltage to about 3volts (330 ohm) on the diode side.

    The transistor your recommend is TIP120. I don't have this part. Would 2n2905 suffice? 2n2222, or 3904? Also have to-220 ab mosfet.

    I see you went to 24 volts on the transistor side. Is the neccesary when using a 6vdc coil relay?


    Thanks,
    Jim
     
    Last edited: Nov 29, 2014
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Something like this.
    Max.
     
  7. widpyro

    Thread Starter New Member

    Nov 28, 2014
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    Thanks Max,
    I had it working, and then somehow blew out the infrared led, so everything's on hold till I get more parts. I'm going to order the exact parts you specified so there are no problems. I'll let you know how it works out!
    Thanks again,
    Jim
     
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