Is This the Ideal Solution for Switching 120V 3A AC Lines?

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SUMMARY

The discussion focuses on a solution for switching 120V 3A AC lines using a BT134-600E TRIAC and a MOC3021 optoisolator. The TRIAC is rated for up to 4A with a maximum gate current of 2A, while the optoisolator requires a trigger current of approximately 20mA. The user calculated the necessary current limiting resistors as 100 Ohms for the optoisolator and 180 Ohms for the TRIAC gate. The design is deemed effective, with a recommendation to include snubbers for inductive loads.

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Electrical engineers, hobbyists designing AC control circuits, and anyone involved in switching applications requiring TRIACs and optoisolators.

jordanstreet
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Hey guys I'd like to run a few things by you guys. I will be switching 120V 3A AC lines and am considering the following solution. I do not need synchronous switching by the way.

This TRIAC
http://www.digikey.com/product-detail/en/BT134-600E,127/568-5015-5-ND/1155119
The datasheet says its rated up to 4A and has a max gate current of 2A.

This Optoisolator
http://www.digikey.com/product-detail/en/MOC3021/160-1374-5-ND/385844
The datasheet lists the trigger current at about 15mA so I'll go with 20mA to be safe, and has a peak surge current of 1A.

I will be triggering the optoisolator with 3.3V signals.

So with these parameters I've gone with
(3.3V - 1.3V) / .02A = 100 Ohms for the diode current limiting resistor on the optoisolator input.
170Vpk / .95A ~= 180 Ohms for the gate current limiting resistor on the triac

I will be using this schematic
http://www.simpleio.com/design/triacout/images/TriacOut4Sch_L.gif

Does this all sound good?
 
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To me the design looks good. The only thing I can think of is that if the load is at all inductive, you should have snubbers on the main triacs.
 

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