diodes polarity in power supplies

Discussion in 'DIY' started by brad44, Nov 14, 2017 at 5:30 PM.

  1. brad44

    brad44 Active Member

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    Generally, what would occur if a diode was installed in the wrong direction in a rectifier/power supply?

    Also, what occurs if a diode was installed in the wrong direction in a bias supply?
     
  2. whoaru99

    whoaru99 Epic Member

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    1. Most likely a short, I believe (to clarify, when there is more than one, and others are installed correctly).
    2. Positive bias, which might blow a bias supply cap if the cap is installed correctly (positive to ground, generally, for tube amp bias supply). If the cap didn't blow and you manage to fire up the amp, I'd expect the tubes might not like that so much.
     
    Last edited: Nov 14, 2017 at 6:25 PM
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  3. slimecity

    slimecity Super Member

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    Are you asking for yourself, or "for a friend....?"o_O
     
  4. brad44

    brad44 Active Member

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    I haven't made that mistake yet, I was trying to explain to my son was rectification was and that tubes and diodes are both used for the task.

    Thanks whoaru99 for your reply.
     
  5. slimecity

    slimecity Super Member

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    The purpose and how a diode is depicted in a schematic symbol is pretty telling - a diode will only pass voltage one way, if its inserted the wrong way, like whoaru99 states, it may well be perceived by the circuit as a dead short.

    2000px-Diode_symbol_svg.png
     
  6. sregor

    sregor AK Subscriber Subscriber

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    1) Most supplies, where more than one diode connect together, will give you excess current draw, and usually end up with a short and a blown fuse. However, if just one diode (like a simple half wave rectifier) the filter caps will usually vent or blow up or just go open, and all kinds of stuff will happen to components which connect to the supply.
     
  7. giorgi

    giorgi Member

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    amplifier no work.
     
  8. gadget73

    gadget73 junk junkie Subscriber

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    The problem I always had with these is that its backwards. Electrons don't flow from positive to negative, so the diode symbol always messes me up.
     
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