Fast zener diode substitute

Discussion in 'Hobby Electronics' started by Yvan, Feb 6, 2010.

  1. Yvan

    Yvan Guest

    I decided to built this:

    http://notes.ump.edu.my/fkee/e-Magazine/Elektor 2004/Articles/E/e04b020.pdf

    It keeps the battery a little bit active, preventing sulphation by
    loading the battery with a hefty current (40 A) for a short interval
    (50 μs) approximately every two minutes.

    But they used a fast zener diode (BZT03 27V) across the FET for
    protection, as rather large voltage spikes can occur when the FET
    switches off.

    I can not find this diode where I am, so can you suggest a substitute? I
    guess I can not just put regular 27V zener diode here?


    --
    ___ ____
    /__/ / \ ** Registrovani korisnik Linuksa #291606 **
    / / \/ /\ \ ** Registered Linux user #291606 **
    /__/\____/--\__\ ** http://counter.li.org/ **
     
    Yvan, Feb 6, 2010
    #1
    1. Advertising

  2. Yvan

    Yvan Guest

    Nedavno ian field napisa:

    > Have a look at the data sheet for the TL431 adjustable zener, you put
    > a potential divider (2 resistors or a trimpot) across it with the
    > tap/wiper to the control input to adjust the zener voltage, if you
    > need it to be particularly fast just put a few tens of pF capacitance
    > in parallel with the top leg of the divider.



    I am electronics newbie, this sound complicated :-(


    --
    ___ ____
    /__/ / \ ** Registrovani korisnik Linuksa #291606 **
    / / \/ /\ \ ** Registered Linux user #291606 **
    /__/\____/--\__\ ** http://counter.li.org/ **
     
    Yvan, Feb 6, 2010
    #2
    1. Advertising

  3. Yvan

    Ban Guest

    "ian field" <> schrieb im Newsbeitrag
    news:iombn.346312$2...
    >
    > "Yvan" <> wrote in message
    > news:hkkrgn$hlo$-september.org...
    >> Nedavno ian field napisa:
    >>
    >>> Have a look at the data sheet for the TL431 adjustable zener, you put
    >>> a potential divider (2 resistors or a trimpot) across it with the
    >>> tap/wiper to the control input to adjust the zener voltage, if you
    >>> need it to be particularly fast just put a few tens of pF capacitance
    >>> in parallel with the top leg of the divider.

    >>
    >>
    >> I am electronics newbie, this sound complicated :-(

    >
    > Not at all, search and download the data sheet - it has application
    > examples for you to follow, to speed it up you only need add a small
    > disc-ceramic capacitor from cathode to control pin.
    >

    What happens with that small part if up to 10A want to flow thru it?
    ban
     
    Ban, Feb 7, 2010
    #3
  4. Yvan

    Yvan Guest

    Nedavno ian field napisa:

    >>> Have a look at the data sheet for the TL431 adjustable zener, you
    >>> put a potential divider (2 resistors or a trimpot) across it with
    >>> the tap/wiper to the control input to adjust the zener voltage, if
    >>> you need it to be particularly fast just put a few tens of pF
    >>> capacitance in parallel with the top leg of the divider.

    >>
    >>
    >> I am electronics newbie, this sound complicated :-(

    >
    > Not at all, search and download the data sheet - it has application
    > examples for you to follow, to speed it up you only need add a small
    > disc-ceramic capacitor from cathode to control pin.



    I've been suggested in another NG to just use any 3-5W 27V zener diode.
    What do you think?


    --
    ___ ____
    /__/ / \ ** Registrovani korisnik Linuksa #291606 **
    / / \/ /\ \ ** Registered Linux user #291606 **
    /__/\____/--\__\ ** http://counter.li.org/ **
     
    Yvan, Feb 7, 2010
    #4
  5. Yvan

    Ban Guest

    "ian field" <> schrieb im Newsbeitrag
    news:ZIBbn.19222$2...
    >
    > "Yvan" <> wrote in message
    > news:hkloo9$n61$-september.org...
    >> Nedavno ian field napisa:
    >>
    >>>>> Have a look at the data sheet for the TL431 adjustable zener, you
    >>>>> put a potential divider (2 resistors or a trimpot) across it with
    >>>>> the tap/wiper to the control input to adjust the zener voltage, if
    >>>>> you need it to be particularly fast just put a few tens of pF
    >>>>> capacitance in parallel with the top leg of the divider.
    >>>>
    >>>>
    >>>> I am electronics newbie, this sound complicated :-(
    >>>
    >>> Not at all, search and download the data sheet - it has application
    >>> examples for you to follow, to speed it up you only need add a small
    >>> disc-ceramic capacitor from cathode to control pin.

    >>
    >>
    >> I've been suggested in another NG to just use any 3-5W 27V zener diode.
    >> What do you think?

    >
    > The best thing to do is study the data sheet;
    >
    > http://www.ieeta.pt/~alex/docs/DataSheets/BZT03.pdf
    >
    > It mentions that these zeners are suitable for transient suppressors, that
    > might be connected to the idea that these are fast zeners, you could
    > search under transient suppressors and select a substitute from the
    > results.
    >


    The same datasheet states a non repetitive current of 7.9A in transient
    suppression, maybe we dont need that much for the application, but certainly
    a long lead will give some inductive kick when driven with 40A.

    ciao Ban
     
    Ban, Feb 7, 2010
    #5
  6. Yvan

    Yvan Guest

    Nedavno ian field napisa:

    > BTW: thanks for the URL - backspacing it found some pretty interesting
    > magazines & e-books.



    Yeah, I noticed that too :)


    --
    ___ ____
    /__/ / \ ** Registrovani korisnik Linuksa #291606 **
    / / \/ /\ \ ** Registered Linux user #291606 **
    /__/\____/--\__\ ** http://counter.li.org/ **
     
    Yvan, Feb 7, 2010
    #6
  7. Yvan

    Yvan Guest

    Nedavno ian field napisa:

    >> I've been suggested in another NG to just use any 3-5W 27V zener
    >> diode. What do you think?

    >
    > This search might be a good starting point;
    >
    >

    http://www.google.co.uk/search?sourceid=navclient&ie=UTF-8&rlz=1T4GZAZ_en-GBGB333GB333&q=p6ke


    I am electronics newbie, are you suggesting that I can just use 27V P6KE
    in place of BZT03 without modifications?

    There are uni-polar and bi-polar P6KE, which one should I use?


    --
    ___ ____
    /__/ / \ ** Registrovani korisnik Linuksa #291606 **
    / / \/ /\ \ ** Registered Linux user #291606 **
    /__/\____/--\__\ ** http://counter.li.org/ **
     
    Yvan, Feb 8, 2010
    #7
  8. Yvan

    Yvan Guest

    Nedavno ian field napisa:

    > I was suggesting you use that search as a starting point, download the
    > data sheets and compare the spec with the type you want to replace.



    Since I do not know what values to compare, that does not help a lot :-(
    My knowledge in electronics is limited to finding schematics on the
    Internet, drawing a board in eagle, and soldering components to it.


    > I've had a cursory glance at the schematic you plan to build, and I'm
    > a little sceptical about "battery revitalisers" that take pulsed
    > current without incorporating a float charger to replenish the energy
    > taken - if left and forgotten it will eventually discharge the battery
    > and cause sulphation.



    This circuit is not a battery revitaliser as I understand it this is
    sort of sulphation preventer. I am also building battery revitaliser:

    http://home.comcast.net/~ddenhardt201263/desulfator/n_channel_schem.gif


    > It is also possible to do the same job with a much simpler circuit.
    >
    > If you start with a simple current limiting PSU as a float charger,
    > you can add a zero-crossing detector to the rectifier section and use
    > the narrow pulses to switch the MOSFET which then takes pulses of
    > current from the battery as in the Elektor project.


    As I wrote I have (very) limited knowledge in electronics, so unless you
    give me a link to the schematics, this does not help. I have a lot to
    learn, but very little time for that, unfortunately.


    --
    ___ ____
    /__/ / \ ** Registrovani korisnik Linuksa #291606 **
    / / \/ /\ \ ** Registered Linux user #291606 **
    /__/\____/--\__\ ** http://counter.li.org/ **
     
    Yvan, Feb 8, 2010
    #8
  9. Yvan

    Yvan Guest

    Nedavno ian field napisa:

    > I suggest you make
    > the time to stick your nose in a book and learn some of the basics.



    OK, thanks.


    --
    ___ ____
    /__/ / \ ** Registrovani korisnik Linuksa #291606 **
    / / \/ /\ \ ** Registered Linux user #291606 **
    /__/\____/--\__\ ** http://counter.li.org/ **
     
    Yvan, Feb 9, 2010
    #9
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. looking for fast zener diodes

    , Aug 4, 2003, in forum: Electronic Components
    Replies:
    2
    Views:
    603
    K Wind
    Aug 8, 2003
  2. Ajay

    Zener diode with fast switching

    Ajay, Sep 16, 2004, in forum: Electronic Design
    Replies:
    4
    Views:
    1,436
    Ken Smith
    Sep 17, 2004
  3. Bicio

    Diode + Diode Zener and Inductive load

    Bicio, May 21, 2008, in forum: Electronic Design
    Replies:
    8
    Views:
    1,062
    Spehro Pefhany
    May 22, 2008
  4. Yvan

    Fast zener diode substitute

    Yvan, Feb 6, 2010, in forum: Electronic Design
    Replies:
    21
    Views:
    1,172
  5. Replies:
    18
    Views:
    409
    Phil Hobbs
    Aug 20, 2013
Loading...

Share This Page