About zener codes

Discussion in 'The Projects Forum' started by MMH, Feb 24, 2013.

  1. MMH

    Thread Starter Member

    Feb 8, 2013
    143
    4
    Hello there!! I have some zener diodes. on them it is written "2". That means it is two volts. Right?However on the packet, it is written 1.8v zener diodes. which one is true?

    Thanks in advance for your help
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    No.

    What is the full part number? Or are you saying "2" is the only marking on the diode?
     
  3. MMH

    Thread Starter Member

    Feb 8, 2013
    143
    4
    Thanks for answering!! On one side of the diode it is printed "2" and on the other side,"B1". It looks sth like this:
    Taking the blue band to the left,(Diode original color-orange) it is written "B1". turning the diode as if it is the axle of a motor, there is written "2". Now I dont understand what that is.:confused:
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    Get a 9V battery and connect a 1kΩ resistor in series with the diode and battery.
    Measure the voltage across the diode. Reverse the diode (or battery) and measure again.
     
  5. #12

    Expert

    Nov 30, 2010
    16,248
    6,745
    You have no right to expect the manufacturers to print reasonable information on a zener diode. Do as MrChips said to find the truth.
     
  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,981
    3,710
    There is a good chance that it is a 12 volt zener (B12 the last digits). Several manufacturers use this protocol to indicate zener voltage (e.g. 5B6 is a 5.6volt zener and 10B is a 10 volt zener (B is at the end on all zeners over 10 volts in some manufacturer's series).

    If it is 12 volt, then you will need two 9 volt batteries in series. Likely a 5 ma current so use a 1000 to 1500 ohm resistor (1200 ohm preferred).
     
  7. MMH

    Thread Starter Member

    Feb 8, 2013
    143
    4
    Thanks for answering!! I used a 5v usb port instead of a 9v batt. When in reverse bias, the voltage is 1.863 and in forward bias, the voltage is 0.729. So whats the Zener voltage?
     
  8. Meixner

    Member

    Sep 26, 2011
    116
    21
    It would be 1.8 Volts
     
    MMH and #12 like this.
  9. MMH

    Thread Starter Member

    Feb 8, 2013
    143
    4
    Thank You very much!!!!

    But how did you find it?? Is it because in reverse bias, the voltage is 1.863??
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    When forward biased a zener behaves like a regular diode.
    Zener action occurs as avalanche breakdown when the diode is reversed biased.
     
  11. DickCappels

    Moderator

    Aug 21, 2008
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    632
    Mr. Chips rounded the measured number "1.863" to 1.8 because 5% and 10% tolerances are common and common practice is to specify a component's value with appropriate resolution.
     
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