4N33 Optocoupler

Discussion in 'General Electronics Chat' started by sphix, Mar 15, 2012.

  1. sphix

    Thread Starter New Member

    Mar 15, 2012
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    I have a optocoupler QTC 4N33 with three that has 9716K and two that has 9630K marking. I had trouble with Isolated bi-directional motor control using two of these 4N33 and two relays. In my troubleshooting, I've finally come to a conclusion not all 4N33 are the same.

    one of these (9630K) was able to drive the UTV6-12V-SH and/or 12VDC 30/40A relays, but not the other four. I've tested the other four and it correctly drives the LED light (12v source with 330ohm). the one that worked for my relay does not - it's lit. However, when connected to relay it does tick-noise when controlled from pin1,2 connected to 3.3v source (manual switch); the other four does not.

    can someone explain?
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    You bought those on ebay, right? That's what comes up in Google. The coil has 0,8W, I assume at 12V, so coil current at 12V would be = 67mA.

    CTR min is 500%, i.e. you need 13,4mA forward current to make sure it switches the relay.

    1. connect 12V directly to the relay coil and measure the current with multimeter or measure the coil resistance with an ohmmeter
    2. check if it has a built-in diode on the coil. Do you have a datasheet of the relay?
    3. how do you drive the optocoupler? I assume with "LED light" you mean a load at the output of the optocoupler?
     
  3. jimkeith

    Active Member

    Oct 26, 2011
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    The numbers indicated are date codes 1997, week 16 and 1996, week 30.
    Note that the spec sheet indicates a wide range of current transfer ratio, so yes indeed they are not all they same--I suspect that the ones with the high CTR are the ones that function. Also, a low value resistor is required to get adequate LED current to function--3.3V is a low source voltage for driving LEDs and may droop with load.
     
  4. sphix

    Thread Starter New Member

    Mar 15, 2012
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    https://docs.google.com/open?id=0B6Z-aWx_wsYycUxNancxQTlSZk93ekt5aFVDbHZ3QQ
    https://docs.google.com/open?id=0B6Z-aWx_wsYyNkx4eUpZSW9UNnkyVlZVbDhnZzZlQQ

    I was using a 3.3v microcontroller source voltage to drive the optocoupler.
    All 5 optocouplers I have close/open circuit in response. It just that, one optocoupler is able to drive the relay as intended while not the LED circuits; whereas four other optocouplers are able to drive the LED circuits while not the relay circuit. for clarification, I have two different simple circuit for this troubleshooting.

    thanks for any input.
     
  5. sphix

    Thread Starter New Member

    Mar 15, 2012
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  6. sphix

    Thread Starter New Member

    Mar 15, 2012
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