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Optocoupler tester very useful and easy to build.

andrasoni_lucian 30 Maj 2015 12:46 1872 7
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  • O autorze
    andrasoni_lucian
    Poziom 8  
    Offline 
    andrasoni_lucian napisał 75 postów o ocenie 11. Mieszka w mieście CLUJ-NAPOCA. Jest z nami od 2014 roku.
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  • #2 14732436
    elektro155
    Poziom 26  
    What is it supposed to do?
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  • #3 14732627
    andrasoni_lucian
    Poziom 8  
    I think it's pretty obvious, is a device for checking in active mode of optocouplers.
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  • #4 14732675
    nsvinc
    Poziom 35  
    This device doesn't actually test anything useful. It can only indicate basic failures of the IR LED or phototransistor inside the optocoupler. Such 'tests' can be done with an universal multimeter.
    Or, perharps, you have hundreds or event thousands of scrap optocouplers, and you built this device for making quick batch tests?

    A real testing device for optocouplers should, at least, measure CTR and I(c-e sat). Bandwidth measurement would be nice, too.

    But you didn't consider the currents thru the optocoupler's LED vs. CTR. Assuming CTR=100%, If=Ic, so you feed the LED with 14mA, and on the transistor side, Ic equals also 14mA. Most non-Darlington devices have a CTR of much less than 100% (usually around 60%), and it has a non-linear relation to the LED forward current. Tests performed by your device are virtually useless...
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  • #5 14732890
    andrasoni_lucian
    Poziom 8  
    I never claimed to have a performant, is just to make you an idea, when the optocoupler is clearly defective. The multimeter can only see LED and phototransistor is possible if short or shows resistance (in most cases, it is interrupted) .Of course they can not accurately measure all parameters.And ... I usually use new components ...Electronics quality can also do in Romania .It can delete if you believe that is completely unnecessary.
  • #6 14732919
    nsvinc
    Poziom 35  
    andrasoni_lucian napisał:
    I never claimed to have a performant, is just to make you an idea, when the optocoupler is clearly defective.

    OK, this tester can say that an optocoupler 'kind of' works, or is totally dead, but it is impossible to catch minor defects like partially burnt off LED (yes, it happens).
    But, if the current functionality of the device fits your needs, that is still OK :) What I stated earlier is just my own opinion.

    andrasoni_lucian napisał:
    I usually use new components

    Well, so why build a testing device at all?
  • #7 14734068
    Jacek_paw
    Poziom 16  
    nsvinc napisał:
    Well, so why build a testing device at all?


    Because it is quite often to buy brand new broken component.
  • #8 14736762
    andrasoni_lucian
    Poziom 8  
    Yes, this is why, unfortunately are quite a few fake components market
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