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Thread: Series or Parrallel;

  1. #1
    Join Date
    Jul 2005
    Location
    Kansas City
    Posts
    211

    Default Series or Parrallel;

    Any advise on to series or Parallel some diodes off of an Flex Mod, I am doing a quad build and looking for experience and any pros or cons. Also how to set up the Flex for each way?

    Larry

  2. #2
    Join Date
    Jul 2009
    Location
    The Netherlands
    Posts
    1,458

    Default

    Hi Larry,

    I am busy doing a quad red (not the fancy stuff you see around here, just some bodging around). I use 2 flexmods, both driving 2 diodes parallel (Long open cans!).

    What i did was:
    Connect a amp meter, set biascurrent to 150mA
    Then set max. current to 500mA (so each diode gets around 250mA).
    Works fine for me.
    I have 2 small resistors of 4Ohm in parallel with each diode (don't pin me to the exact value, can look it up if you like).... for better load balancing.

    Here is a picture, if you look close you can see the resistors in the positive line.

    Click image for larger version. 

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    Don't mind the colors of the wire to the diodes in the middle/right blue is positive and red is minus.
    The A on the lasorb is Anode (and thus positive).
    But in the positive line you see the diodes, and as you can see this needs some fixing, hope to have it with me on the lem, need some help from "the masters of the (red) universe" aka Pitbull and Andy_con to finish it off (mirror placement and cube).

    Driving more than 1 diode of a flexmod has as biggest disadvantage that at some point one diode is always having a different treshold than the other. So at some point one diode will start emitting a very faint red dot , while the other is still off.
    I choose to have a small red dot to keep some linearity, but that's personal.
    Even my Kvant Red emits a small red dot when no voltage is offered to the modulation input.

    Some others run in series, but that has other disadvantages i am not sure how to explain. But maybe some others can share their views as well to help Larry out ?
    Last edited by hobbybob; 09-25-2010 at 12:53.
    I didn't fail !
    I just found out 10,000 ways that didn't work.

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