> Most of the ones I have found are rated at 400V, xA, ymA. I assume as long > as on the mA side I remain below what my MOC30xx can handle, I'm pretty much > good to go. The TRIAC should be rated at a current handling capacity well above your load. For your application, most will be. As you say, gate current should be less than the MOCxxxx can handle. This will generally be the case. You will need to do a little design from the datasheet to size the gate resistor. > But, I have noticed there is an option for isolated and non-isolated. > > Can someone tell me what the difference is and which one would be more > appropriate? I'm still trying to find more info on the difference between > those key types of triacs, but I haven't yet - most docs have just talked > about the basic principal of triacs. Isolation in this concept is a mechanical and not an electronic principle. "Isolated" just means that the metal tab is not electrically connected to any part of the TRIAC's circuitry. It is an excellent idea to use isolated devices for experimenting and when the design is not critical. It stops you accidentally connecting things to your circuit accidentally. An isolated TRIAC will almost always have a slightly higher thermal resistance from internal die to case so it will nit be able to be operated at quite as high a power level but this will not bother you here. I recommend an isolated TRIAC for your purpose if price is not extremely different. 9Usually only slightly dearer). If there are "snubberless" versions these are also worthwhile for beginners. Note that you MAY need a modest heatsink on the TRIAC depending on current level.- consult data sheet for specs. If driving lightbulbs do note that inrush current at turn on is many times the operating current. Not a problem usually unless you are switching quite rapidly but wit time for bulb to call OR if TRIAC is rated close to on current. RM -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.