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How to test a Schmitt triggers

Discussion in 'General Electronics Chat' started by Gregory, Dec 25, 2017.

  1. Gregory

    Gregory Member

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    [​IMG]I have a IC CD4093BCN Schmitt Triggers
    What circuit do I require to test this Ic
     
  2. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Just google 4093 oscillator.

    Mike.
     
  3. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Remember to connect the inputs of any unused gates to eithe the +ve rail or -ve rail, otherwise you may get weird results.
     
  4. dave

    Dave New Member

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  5. AnalogKid

    AnalogKid Well-Known Member

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    ONLINE

    It would take 8 different oscillator configurations to test a part to see if the gate functions work, but that still would not do things such as characterize the different threshold voltages. Which parameter(s) are you testing for? And why?

    ak
     
  6. Pommie

    Pommie Well-Known Member Most Helpful Member

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    He just asked for a circuit so I gave him one of the most common ones. If he clarifies his question then we may be able to clarify our answers.

    Mike.
     
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  7. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Turn the question around.
    How would you test a 2 input NAND gate?

    upload_2017-12-26_7-5-48.png

    The oscillator idea is good. It test the Schmitt Triggers function but not the 2 input NAND function.

    I would probably use two switches on the two inputs and a resister + LED on the output. Only test if it is a real 2-NAND. Not test the "Schmitt Triggers".

    Why do you want to test? How good of a test do you need?
     
  8. audioguru

    audioguru Well-Known Member Most Helpful Member

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    In my career and hobby I bought probably thousands of ICs and never found a bad one. Maybe because I buy Name Brand parts from a local real electronic parts distributor not cheap junk from ebay, Amazon or Aliexpress.

    I had an equalizer product manufactured and tested. All parts were from as above. 25,000 equalizers were made and only two failed. One had a bad electrolytic capacitor and the other had its quad opamp IC mounted backwards. The final tests were very detailed and all ICs performed perfectly. The ICs were not tested before assembly.
     
  9. Gregory

    Gregory Member

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    I am trying to repair my welder I have got it running but I can not get the welder to change from spot mode to weld mode.
    I operate the switches but no change.
    The only way I know is to test all components I do not have a circuit digram.
    I know what voltage is on the feed motor.and and welding torch triger.
    If you can help me to find the fault I would apperiate.
    If you want more information then I will try to help you out.
    I need to fix this welder
    Greg
     

    Attached Files:

  10. schmitt trigger

    schmitt trigger Active Member

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    A simple and reliable way to test Vth(+) and Vth(-) and understanding the hysteresis concept, as long as one has a two-channel scope. Simultaneously monitoring input and output.
    I've used this trick myself.

    Another, if one has multifunction generator, is to apply a triangle wave at the input. And monitor it again with a two-channel scope.
     
  11. Gregory

    Gregory Member

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    Sorry but I do not have a scope
     
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    That's no way to repair anything, and is unlikely to result in a cure.

    As there's no circuit, then draw one out - and start fault finding from there.
     
  13. Gregory

    Gregory Member

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    Owing to the being a double sided do I draw each side seperate .
    I have never done this befor but willing to give it a go with the forum's help
    Where do I start and what side
    Thank you
     
  14. Gregory

    Gregory Member

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    The program circuit maker Will it run on my I pad.
    If not is there one for my Ipad
     
  15. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Google "schematic capture MacOS"
     

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