> I think this is what we're all thinking of. Yes, that's it. My question (posed to someone else privately) is: Why do all the diagrams I see for this sort of thing typically use a BJT? Is there any reason that a BJT is preferred over a MOSFET? Could one just as easily use a MOSFET here? I plan on having up to 3 devices being controlled by relay circuits like this, it seems that it would be easy to just get an IC that has several transistors on it and wire it up like that. > You can get both the transistor and diode in a TIP series > Darlington transistor package. I used automotive relays > in my homebuilt thermostat project. Do they make several TIP120 devices in a package? say 3 or 4? I find Fairchild's site very difficult to navigate -- I can't find Darlingtons in their product groups unless I search for them and then I just get listings. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics