Suitable replacement for a 47V Zener diode...

Discussion in 'The Projects Forum' started by JohnnyD, Dec 28, 2007.

  1. JohnnyD

    Thread Starter Well-Known Member

    Aug 29, 2006

    I need to build this circuit but I can't get hold of any 47v zener diodes. What can I do instead? Can I use two lower voltage zeners in series, or a voltage regulator?

    It needs to be a very consistent power source, as it's being used to provide +48v phantom power for expensive microphones.

    Thanks for any suggestions :)
  2. kubeek


    Sep 20, 2005
    Yes you can use multiple zeners in series or some 47V regulator, but the latter one will be quite hard to get.
  3. hgmjr

    Retired Moderator

    Jan 28, 2005
    Digikey has a 5 watt 47 volt zener with the digikey part number 1N5368BRLGOSTR-ND. It is an axial leaded package.

  4. mrmeval

    AAC Fanatic!

    Jun 30, 2006
  5. SgtWookie


    Jul 17, 2007
    You need to be careful with this circuit. You haven't really provided enough information.

    However, just forging ahead without enough intel (which has traditionally been a forte of Marines ;)) I'll suggest that your requirements might be met by using a couple of LM317s; one supplying a "floating ground" for the other.

    Of course, I'm assuming that your DC source does not exceed 72 volts -
    wait, what were we talking about? :confused: :rolleyes:
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    The circuit is not well designed. The capacitors are rated 50 volts, with an output of 48 volts. The voltage out of the bridge has to be a volt or two above 48, so the caps are right at the self-destruct point.

    Use 100 volt rated capacitors. Don't expect good regulation.
  7. JohnnyD

    Thread Starter Well-Known Member

    Aug 29, 2006
    thanks for all the suggestions guys.

    I did indeed forget to mention that the AC voltage from the transformer is 40v.

    The image i posted up is the original circuit design by Allen & Heath but it is an old design from the 80s so things may have come on a bit since then. The reason I need this phantom power supply is because I have an A&H mixing desk but it came without the phantom power circuit board in the power supply so I want to make my own one to supply the phantom power to the mixer.

    I think I'll go with the suggestion from mrmeval..
  8. John Luciani

    AAC Fanatic!

    Apr 3, 2007
    National Semiconductor makes the LM317HV which is an adjustable regulator that
    can be trimmed up to 57V. I believe there are a couple of other sources for
    this part.

    (* jcl *)