MOC3022 Optocoupler Testing

Discussion in 'General Electronics Chat' started by Randa Mohamed, Nov 25, 2015.

  1. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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    Hello everyone
    I have purchased around 15 pieces of MOC3022 and they are not working ? Not even a single one, How can I test them with an LED for example ?
     
  2. crutschow

    Expert

    Mar 14, 2008
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    How did you test them to know that they are not working?

    To test those isolators that have a triac output, you need an AC source (such as from a transformer output isolated from the mains) and a DC source for the control.

    If you want to use LEDs as a load then you could use two connected in inverse-parallel with a series resistor to limit the current well below the LED's maximum current rating.

    The input control should be a DC voltage in series with a resistor to limit the current to about 20mA.
     
  3. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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    I have used the diode testing option in my multimeter
    Could you provide a schematic for your suggestion ?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    For an application sheet see Fairchild AN-3006.
    These are random phase opto couplers.
    Max.
     
  5. dl324

    Distinguished Member

    Mar 30, 2015
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    Insert LEDs in series with RL in this circuit:
    upload_2015-11-25_10-12-19.png
     
  6. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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    @dl324 I have constructed the schematic you provided, I ignored the diac part, i set the input resistance to 300 ohms the i've connected an LED to the base pin of 2n3904 and there was no output, i removed the led and measured the output using the multimeter but it gives 0 volts
     
  7. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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    12283136_969394273148990_44146943_n.jpg This is my circuit
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Try without the 2n3904 and take pin 2 directly to supply common.
    What AC load are you testing with?
    Max.
     
  9. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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    I wanna control a triac, this is my schematic
    What do you mean by "supply common" ? Sorry English isn't my first language
    111.png
     
    Last edited: Nov 25, 2015
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Common = GND in the schematic.
    I see you have done it.
    Max.
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Between which two points did you measure the output?
    Did you have your DMM set to measure AC volts?
     
  12. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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    @Alec_t

    I've measured the output between the 10 kohm resistor legs, I used DC volts because im supplying the optocoupler diode with 5V from the arduino
     
  13. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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    @MaxHeadRoom

    Yes I've done this and when I measured the dc volts between pins 1 and 2 of the optocoupler I got a voltage drop of 1.7 as I remember. The measured voltage matched my calculations but when I tried to measure the current I got 0 amps. That's why I was suspicious.
     
  14. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    :confused: I don't see a 10k resistor in your circuit ?
    Current in which path?
     
  15. Randa Mohamed

    Thread Starter New Member

    Jun 19, 2015
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  16. dl324

    Distinguished Member

    Mar 30, 2015
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    I meant put two inverse parallel LEDs in series with RL. When you pulse the transistor, the diac should trigger and the LEDs would indicate that.

    You don't need the transistor; I copied the test circuit from the datasheet.
     
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