David Nebenzahl Inscribed thus:

To be honest, I think it's more fun designing things like this that
will operate "directly" off line voltage (i.e., without a
transformer). One of the criteria of this whole deal was to avoid the
use of a transformer.

And in defense of that, there are tons of things in use every day that
operate just this way. Latest example I found were a bunch of electric
staple guns a neighbor gave me that operated directly off 120 volts,
firing a solenoid through a capacitor.

If I were to actually build this, I'm confident I could do it
safely--at least as safely as those staple guns, which have UL, CSA,
etc., compliance.

With all due respect I doubt it !

If you really look closely at the sort of products you mention, and I
could mention many more, they are all constructed in such a way that it
would be very difficult if not impossible for you to be able to touch
any part that would allow you to come into contact with the mains !

By doing what you are wanting to do, and I am not saying "Don't", you
are potentially putting yourself and others at risk of electric shock,
not to mention any other possible hazards.

I personally would want to ensure that I didn't introduce any potential
hazard that could endanger my family, myself or any visitors !

A small relay would do what you want and provide isolation from the
mains supply.

--
Best Reagrds:
Baron.