SCR triggering

Discussion in 'The Projects Forum' started by madmantrapper, Jun 16, 2013.

  1. madmantrapper

    Thread Starter New Member

    Apr 20, 2011
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    OK folks this may get a little long winded. I have two magnets rotating on a flywheel 180 degrees from each other. The magnet poles are reversed. What I want to do is have a charge coil and a trigger coil. The magnet will pass the charge coil ( north to south) to charge a capacitor. At a given distance later the magnet will pass the trigger (north to south). The magnet passing the trigger will fire an SCR discharging it through another coil. 180 degrees from there another magnet will pass the charge coil again, this time south to north, and then again pass the trigger coil firing a different SCR discharging the capacitor through another coil.

    The charge coil will produce about 300 volts. The trigger I'm not sure about. I have a sketch of the circuit I could post if I knew how.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,143
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    That would help. Try taking a screen shot and attaching it to your post. New visitors may be restricted in what they can attach, not sure.
     
  3. sq-aristo

    New Member

    Jun 1, 2013
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    I'm pretty sure the old outboard cap discharge packs used a Darlington transistor
     
  4. madmantrapper

    Thread Starter New Member

    Apr 20, 2011
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  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    What speed is this rotating at?
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Sounds like a capacitor discharge ignition circuit.

    If you google for some schematics there should be a lot of info out there.
     
    sq-aristo likes this.
  7. madmantrapper

    Thread Starter New Member

    Apr 20, 2011
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    Flywheel is turning at about 7,000 rpm.

    Yes it is a capacitor discharge ignition. I am trying to duplicate a power pack. This thing blows often at $80 a clip. I figured I would make my own for near free.

    I have searched the web and found can't find anything to work.
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    What does the engine connect to?
     
  9. madmantrapper

    Thread Starter New Member

    Apr 20, 2011
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    It is a Johnson outboard 15 hp.
     
  10. sq-aristo

    New Member

    Jun 1, 2013
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    A failing power pack is usually a symptom of another fault. Check all connections are tight and clean. I have seen charge and trigger coils on there way out surge and kill power packs. If you have a service manual or the specs and a peak voltage adapter measure the output of charge and trigger coils I think you will find the reason for failure.
    I'm all for DIY but I wouldn't like to spend the time to find it just pop again.
     
    Last edited: Jun 22, 2013
  11. madmantrapper

    Thread Starter New Member

    Apr 20, 2011
    15
    0
    sq-aristo

    I've checked all the peak voltages, no surges. I've checked the coils and everything else I can come up with over the years. I think the trouble might be heat related during slow trolling but I'm not sure of that. I also I another outboard that does the same thing. I'm told it is just something that happens.

    Thanks for the thought,
    Paul
     
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