Wednesday, September 10, 2014

Testing a Diode


 A diode can be tested by checking the forward-to-reverse-resistance ratio indicates the ability of the diode to pass current in one direction and block current in the other direction.
      A germanium diode has a low forward-resistance of several hundred ohms. The reverse resistance is high, greater than 100,000 ohms. Silicon diodes have a higher forward and reverse resistance than germanium. An ohmmeter test of a diode should show a low forward resistance and a high reverse resistance.


      The polarity of the terminals in an ohmmeter appears at the leads of ohmmeter: Red is positive and black is negative or common. If the positive ohmmeter lead is connected to the anode of the diode and the negative lead to the cathode, the diode is forward biased. Current should then flow through the diode and the meter should indicate a low resistance. If the meter leads are reversed, the diode is reverse biased. Little current should flow and the meter should measure a high resistance.
      If a diode shows both low forward and low reverse resistance, it is probably shorted. If the diode measure both high forward and high reverse resistance, then it is probably opened.
      An accurate diode test ca be made with most types of ohmmeters. The forward resistance voltage must be larger than the barrier voltage of the diode (0.7 V for silicon and 0.3 V for germanium) for conduction to take place.
      An ohmmeter can also be used to determine the cathode and anode of unmarked diode. When there is a low reading, the positive lead is connected to the anode and the negative lead is connected to the cathode.
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44 comments:

  1. janeSeptember 10, 2014 at 2:11 AM

    thnaks . This is what im trying to look .

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  2. AnonymousSeptember 10, 2014 at 3:50 AM

    Thanks to this blog. Now i know how will i test a diode! Such a big help. :)

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  3. UnknownSeptember 10, 2014 at 3:50 AM

    very useful info huh :)
    tnx for the post

    ReplyDelete
  4. AnonymousSeptember 10, 2014 at 3:50 AM

    Nice blog. keep it up.

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  5. UnknownSeptember 10, 2014 at 3:51 AM

    It's helpful to the students having this blog. Good job! :)

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  6. UnknownSeptember 10, 2014 at 5:50 PM

    Thank you ma'am for the information about diode :)

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  7. #ArmaniiSeptember 10, 2014 at 7:36 PM

    i thought it was hard to test a diode :>
    but it gave me relief to see that it was that easy :) so glad !

    ReplyDelete
  8. ZAISeptember 10, 2014 at 7:46 PM

    good that you putn a video here...thanks...

    ReplyDelete
  9. UnknownSeptember 10, 2014 at 7:49 PM

    thank you for the information :)

    ReplyDelete
  10. AnonymousSeptember 10, 2014 at 8:03 PM

    love it

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  11. AnonymousSeptember 10, 2014 at 8:05 PM

    NICE :)

    ReplyDelete
  12. AnonymousSeptember 10, 2014 at 8:06 PM

    Thank you Ma'am it helps me alot

    ReplyDelete
  13. PAULA VIDALSeptember 10, 2014 at 8:07 PM

    It is the first time I ever that a germanium diode exist ... Woah .. Mid blowing!!

    ReplyDelete
  14. UnknownSeptember 10, 2014 at 8:09 PM

    This comment has been removed by the author.

    ReplyDelete
  15. AnonymousSeptember 10, 2014 at 8:10 PM

    good that you putn a video here...thanks...

    ReplyDelete
  16. justineSeptember 10, 2014 at 8:28 PM

    nice very informative post plus a video this will be a great help :D

    ReplyDelete
  17. justineSeptember 10, 2014 at 8:28 PM

    nice very informative post plus a video this will be a great help :D

    ReplyDelete
  18. UnknownSeptember 10, 2014 at 8:42 PM

    nice blog ...dami kungt nakuhang info ..about sa diode

    ReplyDelete
  19. UnknownSeptember 10, 2014 at 9:24 PM

    Thanks dito Mam! :D
    Pag binaligtad po ba yung pagtetest ng diode may epekto po ba yun?

    ReplyDelete
  20. UnknownSeptember 11, 2014 at 12:44 AM

    thanks sa info .. it really helps yung mga gusto talga matuto :)

    ReplyDelete
  21. AnonymousSeptember 11, 2014 at 4:20 AM

    Now i know how to test diode. Thanks for this blog for the tutorial and information. :D

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  22. AnonymousSeptember 11, 2014 at 4:24 AM

    Very nice video and presentation.

    ReplyDelete
  23. AnonymousSeptember 11, 2014 at 4:24 AM

    Hey thanks i'll try it out. I really appreciate this blog.

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  24. AnonymousSeptember 11, 2014 at 4:27 AM

    Many multi-meters do not have a diode test setting.
    It would be very helpful if you had covered how to test without a diode setting.

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  25. AnonymousSeptember 11, 2014 at 4:29 AM

    That is very informative and well spoken.

    ReplyDelete
  26. AnonymousSeptember 11, 2014 at 4:30 AM

    Awsome Blog

    ReplyDelete
  27. AnonymousSeptember 11, 2014 at 4:30 AM

    Excellent instruction

    ReplyDelete
  28. AnonymousSeptember 11, 2014 at 4:30 AM

    Love learning from this blog. :D

    ReplyDelete
  29. AnonymousSeptember 11, 2014 at 4:34 AM

    GREAT VIDEO.

    ReplyDelete
  30. UnknownSeptember 11, 2014 at 4:35 AM

    Clearly explained. good job!

    ReplyDelete
  31. AnonymousSeptember 11, 2014 at 4:39 AM

    I got the same multi-tester. I'll try this. Thanks for the video. nice blog.

    ReplyDelete
  32. AnonymousSeptember 11, 2014 at 4:41 AM

    thank you very much for the demonstration, it was very useful and very well represented. Great job.

    ReplyDelete
  33. AnonymousSeptember 11, 2014 at 4:42 AM

    I marked this "liked" thank you very much. thanks for this tutorial. nice blog. :D keep it up.

    ReplyDelete
  34. AnonymousSeptember 11, 2014 at 4:42 AM

    Thank you for the demo

    ReplyDelete
  35. AnonymousSeptember 11, 2014 at 4:43 AM


    This was helpful, thanks. Nice Blog. :D

    ReplyDelete
  36. AnonymousSeptember 11, 2014 at 4:44 AM

    Thanks, It Helped me,wish I had your knowledge!

    ReplyDelete
  37. AnonymousSeptember 11, 2014 at 4:44 AM

    Thanks!! Very instructional!!

    ReplyDelete
  38. ChristianSeptember 11, 2014 at 4:45 AM

    Thank you. I found lots of instructions. But this was the first which tells you what the readings would be if the diode was bad.

    ReplyDelete
  39. MARKSeptember 11, 2014 at 4:46 AM


    Exactly what I was looking for, thanks!

    ReplyDelete
  40. REYSeptember 11, 2014 at 4:47 AM

    Thank you very much for a simple explanation of a diode.

    ReplyDelete
  41. ZaijaSeptember 11, 2014 at 4:47 AM

    Now have an understanding of diodes and their place in the world of electronics.

    ReplyDelete
  42. BANANASeptember 11, 2014 at 4:48 AM

    I like the way you explain everything in simple to understand terms. You should be a teacher of electronics. Great video Thank you.

    ReplyDelete
  43. ANGELICA TO!September 11, 2014 at 10:27 PM

    Dami kong natutunan! THAAAANKSSSS!!!!!!!!

    ReplyDelete

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