Thanks for all the feedback guys. I guess one other problem with using the low voltage switching circuitry is that if it's mains driven, there will always be current drawn from the primary unless it's battery powered. Thanks for that circuit Ron. I think I'd be able to adapt either a push or pull solenoid for the mechanism, but yes you are right about the current and mounting. I want to make this unit to have some visual look about it. Depending what I end up with regarding the solenoid, I want to either cast up or fabricate a bell crank arrangement that will strike the bell. This will be polished brass to match the bell and will be highly visible.
Andy: I'm not really familiar with what's on the market regarding those type of door bells, but I would imagine them to be battery powered and fairly light on. this 10 inch bell will take a bit of force to make a good "gong", or is that "dong"!!!
Thanks for those schematics Ken. I understand the first one with the 2 gongs, but why the need for R1, C1 and D1? I would have thought just the relay actuating the solenoid directly would be adequate.