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Very basic triac circuit problem:

MidAtlantian

May 12, 2015
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Hi,

I am trying to use a triac in a very simple circuit. My circuit uses a MOC3041 isolator to trigger a BTA316 triac. I can wire the 3041 with a 9v dc circuit and an external LED and then I can see that the 3041 is turning on when I power the internal LED. But when I wire the triac to the 3041 - one side (pin 6) to the triac's gate (pin 3) , and the other side through a 150 ohm resistor to the load side of the triac, and turn on the 3041, the triac does not switch on. I am sure this must be as fundamental an error as one can make, but, well, here I am!

Thanks for any suggestions,

MidAtlantian
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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What current are you running the LED in the optocoupler at? And can you show us the circuit?
 

MidAtlantian

May 12, 2015
36
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Hi Steve,

I thought I had not posted this! I found my problem: I had the control loop going from the gate through a resistor into the load side of the triac. Wired to the supply side, it works fine. And yes, when the current through the LED was not high enough, that was a problem, but I'd got that far. :)

However, thank you or your response. As far as posting a schematic, I do not have any software that makes that easy. Are there any you'd suggest? Especiallya more or less intuitive one, that I might not have to spend a lot of time learning.
 

davenn

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Sep 5, 2009
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However, thank you or your response. As far as posting a schematic, I do not have any software that makes that easy. Are there any you'd suggest? Especiallya more or less intuitive one, that I might not have to spend a lot of time learning.

Paintbrush in Windows is as good as any for doing quick schematics
 

MidAtlantian

May 12, 2015
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Paintbrush? Yes, I guess you build a "master page" that you add to up as you need and create symbols. Easy. thanks.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Digikey have an online schematic tool that I often use. You need to register for it but other than that it's free.

Google "digikey schemeit" for more information.
 

MidAtlantian

May 12, 2015
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Dave,

Thank you!! That is quite a gift and saves me doing a lot of work. That looks like most of what I'd use.

Funny, it is "just" one page, but there is really a LOT of stuff - and a lot of work - in it.

MidAtlantian
 

MidAtlantian

May 12, 2015
36
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Steve,

That looks helpful, especially as it has an index of symbols with their names. Often I'll know the name of a component but not the correct symbol, but also, sometimes I'll come across a schematic where I don't know what the symbol means, so that should be useful. However, I'm some distance from telephone exchanges or optical cables, and my internet is often VERY slow, so relying on a link is not the best for me, but this looks very good too. Thanks.

MidAtlantian
 
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