Does it matter which way a triac is connected?


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  1. #1
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    Default Does it matter which way a triac is connected?

    Hi, Obviously it matters that the gate is connected to the correct place but does it matter for A1, A2 and the optoisolator that controls it?

    Since i started playing with triacs ive always connected the live wire to A1 and A2 to the load and the opto. Im trying to design some more space efficient PCBs and it would help a lot if i could connect the live wire to A2 and the load to A1. I assume this is perfectly fine as its AC anyway but what about the opto? Does it matter if the opto is connected to A1 or A2 or does it make a difference if its on the live side or the load side?

  2. #2
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    May 2010
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    Already made the same mistake.

    The pin order around opto and triac must be mantained to keep driving properties.
    Pin4 -> resistor -> Gate
    Pin6 -> mains

    Pin6 if i remember can be connected either to A1 or A2 in parallel but be mains feeded
    (Please correct me if im wrong, fuzzy memory right now)

    Anyway I always base my triac-opto design on this schematic:
    (no snubber there, I use triacs with integrated snubber)
    Attached Images Attached Images  
    "If at first doesn't work, kicking it wont help either"

  3. #3
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    The way ive always done it is almost the same as you except i have the load on the other side of the triac. It always works fine for me but i can understand why its not a good way to do it.

    This new design im working on is actually identical to your schematic so it looks like it will work in any direction (at least for normal bulbs) and my new design should definately work.

    Thanks for your help

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