Door bell help

Off hand, I would think a small mechanical bell, like those used in Burglar Alarm systems. Low current, but loud ringing. Or you could try one of those Piezo things, but I find they are more annoying. -mpm

Not very loud. You could charge a capacitor while the button is pressed and have the sound continue, powered by the capacitor, for a couple of seconds.

Most definitely. You don't get more energy out (as sound) than you put in (as electricity).

For a lot of sound from a small amount of energy, some kind of piezoelectric sounder is probably the way to go. But don't expect tremendous loudness from small amounts of power. And remember that piezosounders are DC devices.

Of course, it only rings as long as the button is down. :-)

Hope This Helps! Rich

Yes.

No - but you need to change the doorbell transformer and you need to run new wires to the car horn. See below.

Change the door bell transformer to a DC supply that is capable of providing the current to the car horn you are using. Run new wires from the supply to the car horn, through a set of relay points. Use the existing doorbell wiring to trigger a 3 second timer that operates the relay.

Ed

a large gong with a motorised beater.

depends what you mean, eg: the gong will continue to emit sound for some time.

there is that issue, I've seen smaller versions of the car horn.

Does the bell have to be ready to go again immediately after ringing? If not, you could be charging a capacitor (storing energy) when the bell is not in use.