On 13 Oct 2020 21:23:11 GMT, Tim+ wrote:

snip

Assuming it's the same model, would the idea be that the first unit
powers the second and both operate when you press the button?

Um no.

Ok ...


Wouldn't they have to be in series to do that (one without the battery
circuit) and then they would both be working on half the voltage
(unless I replace the battery with a 12V one)?

Two battery doorbells, wired “in parallel” to the same bell push.

Yeah, I got that, but then both *batteries* would also be in parallel,
via the solenoid coils? Ok as long as they were the same make / model
/ condition *and* wired the same way round (+/- etc).


If both were powered and commoned at the same bell push, wouldn't
there be the need for diodes on both 'lives' to the bell push so that
they didn't leak voltage back to each other (that would be fairly
doable).

Don’t see why they should need that. They’ll both be open circuit until the
push is pressed.

Yeees, but they would both be in parallel battery wise, unless you had
a dual pole doorbell switch?


Or have I miss something more obvious?

I guess a small relay (coil) in series with the first and actuating
the second could also work?


I think you’re over-complicating things.

See above. ;-)

Cheers, T i m