In article ,
WeeBob wrote:
Hello.

I have an old wired doorbell that has an 18V DC power supply. The
actually transformer has been (I think) channelled into the wall, or
underfloor boards in the attic. i.e. hard to get to.

18v would be unusual for a door bell. Did you measure the voltage from the
power supply with no load? The sort used for this likely has very poor
regulation since it doesn't much matter. Real doorbells will work over a
wide range of voltage.

A new fancy doorbell requires connection to a 8V AC power supply.

Is there a simple way to do this? i.e. 18V DV in, 8V AC out?

If it's an electronic device it will run off DC. So if no internal
transformer, it will accept DC too. The DC will go through its internal
rectifier OK. If so a simple regulator will give you the DC voltage you
want. Exactly what that is, I'm not sure. As a nominal 8v AC supply
depends on how it is rectified etc for the final DC voltage. Can this
device be run off batteries? That would tell you what it needs, DC wise.

--
*The closest I ever got to a 4.0 in school was my blood alcohol content*

Dave Plowman London SW
To e-mail, change noise into sound.