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Zener Diode ID

Discussion in 'Electronic Basics' started by Ronak Shah, Nov 30, 2004.

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  1. Ronak Shah

    Ronak Shah Guest

    This might be the weirdes questen here....
    Well I picked up a miex lot of components and it has about 5-6 Zener
    Diodes... (thats what i think they are) Well the problem is they are sooo
    tiny and hence I cant read the values.. is there a way I can find out the
    values? I mean ID the diode....
    Now that I think of it... are they even Zener diodes? I know 1N914 comes in
    glass case too...
    Is there a way I can find out what this is and what values it holds....
     
  2. John Fields

    John Fields Guest

    Are there stripes around the bodies of the devices?
     
  3. Ronak Shah

    Ronak Shah Guest

    you can hardly see the stripes.... they are more like blogs of ink
     
  4. Get a good ~10x magnifying loupe: Things will just get even tinier
    and harder to read; Eyesight gets worse as one gets older,
    not better.
     
  5. CFoley1064

    CFoley1064 Guest

    Subject: Zener Diode ID
    Hi, Shah. No weird questions here. If they're in a glass case, they're
    probably either signal diodes or zeners. If they're zeners you can usually
    tell the wattage by the size (400mW zeners are smaller than 1W zeners). The
    tiny ones are usually the 400mW ones.

    One thing you might try is cobbling up a 30V power supply, and putting the
    back-biased diodes (Device Under Test, or DUT) in series with an appropriate
    resistor. If they're standard diodes, all the voltage will be across the
    diode. If they're zeners, there will be a zener voltage across the diode, and
    the rest will be impressed across the resistor. Note that this will not be a
    good solution for higher voltage zeners (they will look like standard diodes)
    or schottky diodes (which can break down at 20V, depending). But, if the
    choice is between standard silicon signal diode or low voltage (less than 24V)
    zeners, this will give you a pretty good start.

    Remember to start with a higher resistance value to avoid smoking the zener,
    and after getting an initial indication of zener/avalanche, choose a more
    reasonable resistance to test at something like half rated wattage. (power =
    volts * current).

    ___
    .--|___|---X----.
    | R |
    | |
    | |
    --- DUT -
    -30VDC ^
    | |
    | |
    '----------X----'
    created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de


    Good luck
    Chris
     
  6. Ronak Shah

    Ronak Shah Guest

    I took some advice and got my self the magnifying glass....
    well I can see the following digits....
    on the first one
    1N8
    14B
    C

    on the second one:
    TFK
    1N4 < Not very clear
    733 < 7 is clear the rest I guessed from the blur

    Now I cant see the numbers clearly.. so I am guessing these numbers... does
    anyone recognize these?????
    If you do... are these zeners or regular signal diodes??
    If not do these numbers resemble anything you might recognize ?

    I am kinda new to this.....please advice
     
  7. Glenn

    Glenn Guest

    My guess would be:
    ..5 watt 5.1 volt zener


    Glenn
     
  8. This might be useful:
    http://www.brive.unilim.fr/geii/electronique/docs/cross_ref_puissance.pdf

    This list may give you an equivalent type that you can find on Google.

    That said, the second one is a current type and is on this data sheet:
    http://www.fairchildsemi.com/ds/1N/1N4744A.pdf
     
  9. Bob Masta

    Bob Masta Guest

    A method I use is similar to Chris Foley's, only simpler if you have
    a scope. Just put the unknown device in series with a resistor
    (100K or so) and connect to the AC output of an appropriate
    transformer.

    Look at the voltage across the diode and see what it does.
    You can see the Zener voltage as a clipped half-sine in
    the reverse-bias direction. You can thus read the Zener voltage
    right off the scope face. This makes it quick to characterize
    lots of unknown parts, including telling which end is which.

    Hope this helps!


    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
     
  10. Joerg Hau

    Joerg Hau Guest

    1N8148. Sounds _almost_ like an 1N4148 (Si universal diode); those in
    my stock are labeled in the same fashion.

    Cheers + HTH,

    - Joerg
     
  11. I suspect that is a 1N914B - common small-signal diode.
    1N4733 is a 5.1 volt zener, 1 watt
     
  12. Rich Grise

    Rich Grise Guest

    I thought 1N814 might be in the 1N74x series of zeners, but Newark doesn't
    list it, so I'm guessing 1N914 with a crappy screen.

    I agree on the 1N4733.

    Cheers!
    Rich
     
  13. The 1N814 is a silicon signal diode, it is _not_ a zener diode.
    According to my Moto manual, PRV=40V, Vf=1.0 @ 2mA, Ir=0.1uA, Trr=.25uS.
     
  14. Rich Grise

    Rich Grise Guest

    Well, I just took a WAG, as it's apparently a grab-bag, and figured that
    the 1N914 would be more likely to show up in a grab-bag. ;-)

    Notwithstanding that just because I've never heard of one doesn't mean it
    doesn't exist! ;-)

    Thanks!
    Rich
     
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