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Thread: Optocoupler tester

  1. #11
    Supporting Member darkoford's Avatar
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    darkoford's Tools
    It is my fault that I did not record of the defective optocouples.

    Cheers
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  2. #12

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    Would you be so kind to provide schematics which is suitable to test both of the failure states you mentioned of an optocoupler?
    Thank you.
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    Supporting Member DIYSwede's Avatar
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    DIYSwede's Tools
    No big deal, hegefer:
    -Just hook the (normally open) push-button between the opto-couplers Pin 2 to ground (instead of as per the schematic).
    Then the +voltage will feed the opto-transistor at all times, or rather as long as the +supply is on,
    but the button will draw current through the coupler's LED only when pushed.

    Thus you check that:
    1) The transistor won't lead when the internal LED is off (No push: External LED OFF),
    2) That it'll lead when, and only when PB is pushed (Push and hold: LED lights up), and
    3) That the transistor also shuts off when PB is released (Release PB: LED goes off,
    thus eliminating that no stray, internal current keeps it ON,
    an indeed very rare, but still possible fault mode)

    2 cents

  4. #14

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    Dear DIYSwede,
    Thank you for your quick and detailed answer.
    hegefer

  5. #15
    Supporting Member darkoford's Avatar
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    darkoford's Tools
    Circuit with ground switch:

    Optocoupler tester-screen-shot-09-05-19-01.16-pm.png

  6. #16

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    Quote Originally Posted by darkoford View Post
    Circuit with ground switch:

    Click image for larger version. 

Name:	Screen Shot 09-05-19 at 01.16 PM.PNG 
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    Thank you! I am just about to make one. Very useful tester.

  7. #17
    Supporting Member darkoford's Avatar
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    darkoford's Tools
    Quote Originally Posted by hegefer View Post
    Thank you! I am just about to make one. Very useful tester.
    I don't know if there is another way to check. This is easy to do.

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    Quote Originally Posted by darkoford View Post
    I don't know if there is another way to check. This is easy to do.
    Why one would need another method? It works perfectly!
    Thx

  9. #19
    Supporting Member darkoford's Avatar
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    darkoford's Tools
    It would be easier if it could be tested directly on PCB.


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