hello , i need a triac 90 amps but i couldnt find in the market but i found a thyristor 90 amps so could i make a triac from 2 thyristores ? and is my design right ? i want to use it as on/off .

 

That's an interesting question that I can't answer off the top of my head.

By the way, "thyristor" is a general class of components that include DIACS, SCRs, TRIACs, etc. You're asking about using two SCR's back to back as a TRIAC.

Here's our page on SCR's:
http://www.allaboutcircuits.com/vol_3/chpt_7/5.html
and TRIACs are on the very next page:
http://www.allaboutcircuits.com/vol_3/chpt_7/6.html

According to the E-book, it looks like it will work. However, I haven't verifed it.

 

Try this for a change

 

Yes indeed you can, but the method depends upon the application as you can't simply connect the main terminals in antiparallel and connect the gates together.

One way is to connect two SCRs as two branches of a bridge, with two ordinary diodes in the other two branches.

Sorry I don't have access to drawing facilities where I am at the moment but I'm sure someone will flesh this out.