TRIAC Help

Discussion in 'General Electronics Chat' started by shadowrider, Mar 6, 2012.

  1. shadowrider

    Thread Starter New Member

    Mar 6, 2012
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    Okay. I am trying to control 28vac using 3vdc Best I have come up with is a triac. Anyway to make the triac closed by default and triggered open with the 3vdc? Basically I am trying to make the triac to fail closed allow the 28vac current to flow that way if the micro-controller sending the signal to the triac fails the 28vac will continue to flow. Then will the micro-controller sends a signal it will open the triac interrupting the 28vdc.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    You should use an AC opto-coupler to drive the gate of the triac.
    Or use an AC solid-state relay.
     
  3. praondevou

    AAC Fanatic!

    Jul 9, 2011
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  4. shadowrider

    Thread Starter New Member

    Mar 6, 2012
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    Thanks for the replies. The 28vac current is about 200 ma. Its driving a motor that I am trying to turn off using a triac. I have run the 28 vac to MT1 and MT2 of the triac. I have 3vdc signal coming from a micro controller to trigger that gate on the triac. I am just trying to make the motor always on, unless a signal comes from the microcontroller to open the gate of the triac cutting current to the motor. So is a normaly closed solid state relay the way to go? I am searching on digi key and looking, but the question is how do I tell if its normally closed or normally open? Thanks for your help.
     
  5. shadowrider

    Thread Starter New Member

    Mar 6, 2012
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  6. MrChips

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    Oct 2, 2009
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    Last edited: Mar 7, 2012
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