How to tell if a BJT is PNP or NPN by looking at the circuit? [closed]












1












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enter image description here



enter image description here



Is it possible to tell if a BJT circuit is PNP or NPN simply by looking at the circuit?



For example, for the circuits shown, how can we tell if they're PNP or NPN?










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$endgroup$



closed as off-topic by Andy aka, Eugene Sh., Oldfart, Edgar Brown, Nick Alexeev Feb 28 at 0:27



  • This question does not appear to be about electronics design within the scope defined in the help center.

If this question can be reworded to fit the rules in the help center, please edit the question.












  • 3




    $begingroup$
    Yes. Look at the location/direction of the arrow. That is really a question for your textbook or a search engine.
    $endgroup$
    – Eugene Sh.
    Feb 27 at 16:11








  • 9




    $begingroup$
    I'm voting to close this question as off-topic because there is no evidence of effort to research this answer at all.
    $endgroup$
    – Andy aka
    Feb 27 at 16:19






  • 2




    $begingroup$
    A memory aid: emmiter arrow on an NPN is Not Pointing iN
    $endgroup$
    – Peter Bennett
    Feb 27 at 16:42






  • 1




    $begingroup$
    Another memory aid that has stuck with me for a while: PNP is Pointing iNward Proudly
    $endgroup$
    – Andrey Akhmetov
    Feb 27 at 17:30










  • $begingroup$
    Still another memory aid: PNP is Pee iN the Pot. This works really well if you rotate the symbol 90 degrees counter-clockwise thus making the collector the lid.
    $endgroup$
    – Glen Yates
    Feb 27 at 23:04
















1












$begingroup$


enter image description here



enter image description here



Is it possible to tell if a BJT circuit is PNP or NPN simply by looking at the circuit?



For example, for the circuits shown, how can we tell if they're PNP or NPN?










share|improve this question









$endgroup$



closed as off-topic by Andy aka, Eugene Sh., Oldfart, Edgar Brown, Nick Alexeev Feb 28 at 0:27



  • This question does not appear to be about electronics design within the scope defined in the help center.

If this question can be reworded to fit the rules in the help center, please edit the question.












  • 3




    $begingroup$
    Yes. Look at the location/direction of the arrow. That is really a question for your textbook or a search engine.
    $endgroup$
    – Eugene Sh.
    Feb 27 at 16:11








  • 9




    $begingroup$
    I'm voting to close this question as off-topic because there is no evidence of effort to research this answer at all.
    $endgroup$
    – Andy aka
    Feb 27 at 16:19






  • 2




    $begingroup$
    A memory aid: emmiter arrow on an NPN is Not Pointing iN
    $endgroup$
    – Peter Bennett
    Feb 27 at 16:42






  • 1




    $begingroup$
    Another memory aid that has stuck with me for a while: PNP is Pointing iNward Proudly
    $endgroup$
    – Andrey Akhmetov
    Feb 27 at 17:30










  • $begingroup$
    Still another memory aid: PNP is Pee iN the Pot. This works really well if you rotate the symbol 90 degrees counter-clockwise thus making the collector the lid.
    $endgroup$
    – Glen Yates
    Feb 27 at 23:04














1












1








1





$begingroup$


enter image description here



enter image description here



Is it possible to tell if a BJT circuit is PNP or NPN simply by looking at the circuit?



For example, for the circuits shown, how can we tell if they're PNP or NPN?










share|improve this question









$endgroup$




enter image description here



enter image description here



Is it possible to tell if a BJT circuit is PNP or NPN simply by looking at the circuit?



For example, for the circuits shown, how can we tell if they're PNP or NPN?







bjt






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Feb 27 at 16:11









Jimmy VailerJimmy Vailer

395




395




closed as off-topic by Andy aka, Eugene Sh., Oldfart, Edgar Brown, Nick Alexeev Feb 28 at 0:27



  • This question does not appear to be about electronics design within the scope defined in the help center.

If this question can be reworded to fit the rules in the help center, please edit the question.







closed as off-topic by Andy aka, Eugene Sh., Oldfart, Edgar Brown, Nick Alexeev Feb 28 at 0:27



  • This question does not appear to be about electronics design within the scope defined in the help center.

If this question can be reworded to fit the rules in the help center, please edit the question.








  • 3




    $begingroup$
    Yes. Look at the location/direction of the arrow. That is really a question for your textbook or a search engine.
    $endgroup$
    – Eugene Sh.
    Feb 27 at 16:11








  • 9




    $begingroup$
    I'm voting to close this question as off-topic because there is no evidence of effort to research this answer at all.
    $endgroup$
    – Andy aka
    Feb 27 at 16:19






  • 2




    $begingroup$
    A memory aid: emmiter arrow on an NPN is Not Pointing iN
    $endgroup$
    – Peter Bennett
    Feb 27 at 16:42






  • 1




    $begingroup$
    Another memory aid that has stuck with me for a while: PNP is Pointing iNward Proudly
    $endgroup$
    – Andrey Akhmetov
    Feb 27 at 17:30










  • $begingroup$
    Still another memory aid: PNP is Pee iN the Pot. This works really well if you rotate the symbol 90 degrees counter-clockwise thus making the collector the lid.
    $endgroup$
    – Glen Yates
    Feb 27 at 23:04














  • 3




    $begingroup$
    Yes. Look at the location/direction of the arrow. That is really a question for your textbook or a search engine.
    $endgroup$
    – Eugene Sh.
    Feb 27 at 16:11








  • 9




    $begingroup$
    I'm voting to close this question as off-topic because there is no evidence of effort to research this answer at all.
    $endgroup$
    – Andy aka
    Feb 27 at 16:19






  • 2




    $begingroup$
    A memory aid: emmiter arrow on an NPN is Not Pointing iN
    $endgroup$
    – Peter Bennett
    Feb 27 at 16:42






  • 1




    $begingroup$
    Another memory aid that has stuck with me for a while: PNP is Pointing iNward Proudly
    $endgroup$
    – Andrey Akhmetov
    Feb 27 at 17:30










  • $begingroup$
    Still another memory aid: PNP is Pee iN the Pot. This works really well if you rotate the symbol 90 degrees counter-clockwise thus making the collector the lid.
    $endgroup$
    – Glen Yates
    Feb 27 at 23:04








3




3




$begingroup$
Yes. Look at the location/direction of the arrow. That is really a question for your textbook or a search engine.
$endgroup$
– Eugene Sh.
Feb 27 at 16:11






$begingroup$
Yes. Look at the location/direction of the arrow. That is really a question for your textbook or a search engine.
$endgroup$
– Eugene Sh.
Feb 27 at 16:11






9




9




$begingroup$
I'm voting to close this question as off-topic because there is no evidence of effort to research this answer at all.
$endgroup$
– Andy aka
Feb 27 at 16:19




$begingroup$
I'm voting to close this question as off-topic because there is no evidence of effort to research this answer at all.
$endgroup$
– Andy aka
Feb 27 at 16:19




2




2




$begingroup$
A memory aid: emmiter arrow on an NPN is Not Pointing iN
$endgroup$
– Peter Bennett
Feb 27 at 16:42




$begingroup$
A memory aid: emmiter arrow on an NPN is Not Pointing iN
$endgroup$
– Peter Bennett
Feb 27 at 16:42




1




1




$begingroup$
Another memory aid that has stuck with me for a while: PNP is Pointing iNward Proudly
$endgroup$
– Andrey Akhmetov
Feb 27 at 17:30




$begingroup$
Another memory aid that has stuck with me for a while: PNP is Pointing iNward Proudly
$endgroup$
– Andrey Akhmetov
Feb 27 at 17:30












$begingroup$
Still another memory aid: PNP is Pee iN the Pot. This works really well if you rotate the symbol 90 degrees counter-clockwise thus making the collector the lid.
$endgroup$
– Glen Yates
Feb 27 at 23:04




$begingroup$
Still another memory aid: PNP is Pee iN the Pot. This works really well if you rotate the symbol 90 degrees counter-clockwise thus making the collector the lid.
$endgroup$
– Glen Yates
Feb 27 at 23:04










3 Answers
3






active

oldest

votes


















12












$begingroup$

Quite simply, look at the arrow on the leg.



enter image description here



The arrow will always be on the emitter. Look at where the current flows. The arrow will always follow the current flow.



When the arrow is pointing away from the base, it is an NPN. When pointing towards the base, it is a PNP.






share|improve this answer









$endgroup$





















    4












    $begingroup$

    If the arrow points towards the base it is a PNP, if it points away from the base it is an NPN.



    Further, the arrow will typically be on the more positive leg for PNP and negative for NPN.






    share|improve this answer











    $endgroup$













    • $begingroup$
      Thank you. So would those all be PNP?
      $endgroup$
      – Jimmy Vailer
      Feb 27 at 16:13










    • $begingroup$
      No. Look carefully.
      $endgroup$
      – Eugene Sh.
      Feb 27 at 16:13










    • $begingroup$
      All but one....
      $endgroup$
      – evildemonic
      Feb 27 at 16:14










    • $begingroup$
      Oh so c) (the first one) would be NPN because the arrow above the current source is pointing away?
      $endgroup$
      – Jimmy Vailer
      Feb 27 at 16:15






    • 2




      $begingroup$
      Oh ok thank you. So d) since the arrow is away from the base.
      $endgroup$
      – Jimmy Vailer
      Feb 27 at 16:17





















    2












    $begingroup$

    This diagram should explain everything



    enter image description here
    Any additional questions?






    share|improve this answer











    $endgroup$









    • 1




      $begingroup$
      Your PNP diagram has two emitters. Ic should be labelled "collector".
      $endgroup$
      – Brian Rogers
      Feb 27 at 20:50










    • $begingroup$
      @BrianRogers Thx for spotting this silly mistake. I'll fix it.
      $endgroup$
      – G36
      Feb 27 at 20:57


















    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    12












    $begingroup$

    Quite simply, look at the arrow on the leg.



    enter image description here



    The arrow will always be on the emitter. Look at where the current flows. The arrow will always follow the current flow.



    When the arrow is pointing away from the base, it is an NPN. When pointing towards the base, it is a PNP.






    share|improve this answer









    $endgroup$


















      12












      $begingroup$

      Quite simply, look at the arrow on the leg.



      enter image description here



      The arrow will always be on the emitter. Look at where the current flows. The arrow will always follow the current flow.



      When the arrow is pointing away from the base, it is an NPN. When pointing towards the base, it is a PNP.






      share|improve this answer









      $endgroup$
















        12












        12








        12





        $begingroup$

        Quite simply, look at the arrow on the leg.



        enter image description here



        The arrow will always be on the emitter. Look at where the current flows. The arrow will always follow the current flow.



        When the arrow is pointing away from the base, it is an NPN. When pointing towards the base, it is a PNP.






        share|improve this answer









        $endgroup$



        Quite simply, look at the arrow on the leg.



        enter image description here



        The arrow will always be on the emitter. Look at where the current flows. The arrow will always follow the current flow.



        When the arrow is pointing away from the base, it is an NPN. When pointing towards the base, it is a PNP.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Feb 27 at 16:19









        MCGMCG

        6,56431850




        6,56431850

























            4












            $begingroup$

            If the arrow points towards the base it is a PNP, if it points away from the base it is an NPN.



            Further, the arrow will typically be on the more positive leg for PNP and negative for NPN.






            share|improve this answer











            $endgroup$













            • $begingroup$
              Thank you. So would those all be PNP?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:13










            • $begingroup$
              No. Look carefully.
              $endgroup$
              – Eugene Sh.
              Feb 27 at 16:13










            • $begingroup$
              All but one....
              $endgroup$
              – evildemonic
              Feb 27 at 16:14










            • $begingroup$
              Oh so c) (the first one) would be NPN because the arrow above the current source is pointing away?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:15






            • 2




              $begingroup$
              Oh ok thank you. So d) since the arrow is away from the base.
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:17


















            4












            $begingroup$

            If the arrow points towards the base it is a PNP, if it points away from the base it is an NPN.



            Further, the arrow will typically be on the more positive leg for PNP and negative for NPN.






            share|improve this answer











            $endgroup$













            • $begingroup$
              Thank you. So would those all be PNP?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:13










            • $begingroup$
              No. Look carefully.
              $endgroup$
              – Eugene Sh.
              Feb 27 at 16:13










            • $begingroup$
              All but one....
              $endgroup$
              – evildemonic
              Feb 27 at 16:14










            • $begingroup$
              Oh so c) (the first one) would be NPN because the arrow above the current source is pointing away?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:15






            • 2




              $begingroup$
              Oh ok thank you. So d) since the arrow is away from the base.
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:17
















            4












            4








            4





            $begingroup$

            If the arrow points towards the base it is a PNP, if it points away from the base it is an NPN.



            Further, the arrow will typically be on the more positive leg for PNP and negative for NPN.






            share|improve this answer











            $endgroup$



            If the arrow points towards the base it is a PNP, if it points away from the base it is an NPN.



            Further, the arrow will typically be on the more positive leg for PNP and negative for NPN.







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Feb 27 at 16:13

























            answered Feb 27 at 16:12









            evildemonicevildemonic

            2,538922




            2,538922












            • $begingroup$
              Thank you. So would those all be PNP?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:13










            • $begingroup$
              No. Look carefully.
              $endgroup$
              – Eugene Sh.
              Feb 27 at 16:13










            • $begingroup$
              All but one....
              $endgroup$
              – evildemonic
              Feb 27 at 16:14










            • $begingroup$
              Oh so c) (the first one) would be NPN because the arrow above the current source is pointing away?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:15






            • 2




              $begingroup$
              Oh ok thank you. So d) since the arrow is away from the base.
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:17




















            • $begingroup$
              Thank you. So would those all be PNP?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:13










            • $begingroup$
              No. Look carefully.
              $endgroup$
              – Eugene Sh.
              Feb 27 at 16:13










            • $begingroup$
              All but one....
              $endgroup$
              – evildemonic
              Feb 27 at 16:14










            • $begingroup$
              Oh so c) (the first one) would be NPN because the arrow above the current source is pointing away?
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:15






            • 2




              $begingroup$
              Oh ok thank you. So d) since the arrow is away from the base.
              $endgroup$
              – Jimmy Vailer
              Feb 27 at 16:17


















            $begingroup$
            Thank you. So would those all be PNP?
            $endgroup$
            – Jimmy Vailer
            Feb 27 at 16:13




            $begingroup$
            Thank you. So would those all be PNP?
            $endgroup$
            – Jimmy Vailer
            Feb 27 at 16:13












            $begingroup$
            No. Look carefully.
            $endgroup$
            – Eugene Sh.
            Feb 27 at 16:13




            $begingroup$
            No. Look carefully.
            $endgroup$
            – Eugene Sh.
            Feb 27 at 16:13












            $begingroup$
            All but one....
            $endgroup$
            – evildemonic
            Feb 27 at 16:14




            $begingroup$
            All but one....
            $endgroup$
            – evildemonic
            Feb 27 at 16:14












            $begingroup$
            Oh so c) (the first one) would be NPN because the arrow above the current source is pointing away?
            $endgroup$
            – Jimmy Vailer
            Feb 27 at 16:15




            $begingroup$
            Oh so c) (the first one) would be NPN because the arrow above the current source is pointing away?
            $endgroup$
            – Jimmy Vailer
            Feb 27 at 16:15




            2




            2




            $begingroup$
            Oh ok thank you. So d) since the arrow is away from the base.
            $endgroup$
            – Jimmy Vailer
            Feb 27 at 16:17






            $begingroup$
            Oh ok thank you. So d) since the arrow is away from the base.
            $endgroup$
            – Jimmy Vailer
            Feb 27 at 16:17













            2












            $begingroup$

            This diagram should explain everything



            enter image description here
            Any additional questions?






            share|improve this answer











            $endgroup$









            • 1




              $begingroup$
              Your PNP diagram has two emitters. Ic should be labelled "collector".
              $endgroup$
              – Brian Rogers
              Feb 27 at 20:50










            • $begingroup$
              @BrianRogers Thx for spotting this silly mistake. I'll fix it.
              $endgroup$
              – G36
              Feb 27 at 20:57
















            2












            $begingroup$

            This diagram should explain everything



            enter image description here
            Any additional questions?






            share|improve this answer











            $endgroup$









            • 1




              $begingroup$
              Your PNP diagram has two emitters. Ic should be labelled "collector".
              $endgroup$
              – Brian Rogers
              Feb 27 at 20:50










            • $begingroup$
              @BrianRogers Thx for spotting this silly mistake. I'll fix it.
              $endgroup$
              – G36
              Feb 27 at 20:57














            2












            2








            2





            $begingroup$

            This diagram should explain everything



            enter image description here
            Any additional questions?






            share|improve this answer











            $endgroup$



            This diagram should explain everything



            enter image description here
            Any additional questions?







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Feb 27 at 20:56

























            answered Feb 27 at 16:18









            G36G36

            5,4881511




            5,4881511








            • 1




              $begingroup$
              Your PNP diagram has two emitters. Ic should be labelled "collector".
              $endgroup$
              – Brian Rogers
              Feb 27 at 20:50










            • $begingroup$
              @BrianRogers Thx for spotting this silly mistake. I'll fix it.
              $endgroup$
              – G36
              Feb 27 at 20:57














            • 1




              $begingroup$
              Your PNP diagram has two emitters. Ic should be labelled "collector".
              $endgroup$
              – Brian Rogers
              Feb 27 at 20:50










            • $begingroup$
              @BrianRogers Thx for spotting this silly mistake. I'll fix it.
              $endgroup$
              – G36
              Feb 27 at 20:57








            1




            1




            $begingroup$
            Your PNP diagram has two emitters. Ic should be labelled "collector".
            $endgroup$
            – Brian Rogers
            Feb 27 at 20:50




            $begingroup$
            Your PNP diagram has two emitters. Ic should be labelled "collector".
            $endgroup$
            – Brian Rogers
            Feb 27 at 20:50












            $begingroup$
            @BrianRogers Thx for spotting this silly mistake. I'll fix it.
            $endgroup$
            – G36
            Feb 27 at 20:57




            $begingroup$
            @BrianRogers Thx for spotting this silly mistake. I'll fix it.
            $endgroup$
            – G36
            Feb 27 at 20:57



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