Glass Diode Markings

Discussion in 'General Electronics Chat' started by dturek, Aug 25, 2014.

  1. dturek

    Thread Starter New Member

    Aug 25, 2014
    2
    0
    I have a glass diode part number marking it shows

    8.22. then goes back around to 8 again.

    What is the part number for this diode it is in a DO-7?

    thanks in advance
     
  2. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    Could be an 822 in a DO-35 pkg 6.2V zener.
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    If it is a zener you can measure it with a 10mA current limited bench supply, or a bench supply and a series resistor.
    :)
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Experimenting with the DMM diode check function; I've found that zeners read much closer to the theoretical 0.7V than most other types of diode.

    YMMV.
     
    inwo likes this.
  5. Externet

    AAC Fanatic!

    Nov 29, 2005
    761
    57
    That is wrong polarity. And the DMM may not read beyond a volt to reach the usually higher zener voltages.
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Its not the wrong polarity to measure the Vf - that voltage can tell you a fair bit about the type of diode.
     
    inwo likes this.
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    How much closer?

    I'm always measuring 4148 and 400x rectifier diodes on my fluke and they all measure close to 0.7v.

    It doesn't sound like a very good test to me (although I will check it out in future). :)
     
  8. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Generally speaking; the lower the Vf, the faster the diode - there's actually a bit of a grey area between very small Shottky barrier (signal) diodes and the very fastest plain silicon.

    Diodes like the 1N400x series come in around 0.65 ish - I don't have anything as fancy as a Fluke, but the results across about 5 different DMMs more or less agree.
     
    THE_RB likes this.
  9. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Thanks, you have me intruiged now. I'll have to check it out. :)
     
Loading...